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Table of Contents
Abstract ……….……………………………………………………………….…….. 3
Chapter One ……………………………………………………………………..…. 4
Introduction…………………………………………………………………………………. 4
Statement of Purpose…………………………………………..………………………… 4
Significance of Study………………………………………..………………………………….. 5
Professional Significance………………………………………………..………..………….. 5
Personal Significance……………………………………….……………………………...…… 5
Delimitations…………….……………………………………………..…………………… 5
Limitations…….………………………………………………………..……………………. 6
Assumptions…………………..……………………………….…………………………..… 6
Hypotheses……………………………………………………………………………………… 7
Definition of Terms……………………………………………..……………………….. 7
Operational Definition of Terms………………………..…..……………………….. 8
Chapter Two………………………………………………………………………..……….. 9
Background Research……………………………………….……………………………. 9
Blood flow……………………..………………………………………………………….. 9
Blood flow through body …………………………………………………...… 9
Capillary exchange………………………..……………………………………….. 10
Blood flow redistribution during exercise…………………………………….…………….. 10
Reactive hyperemia……………………………………………………………………… 11
Thermoregulatory blood flow response…………………………………………………….. 11
Summary……………………….……………………………………………………12
Skeletal muscle physiology………………………………………………………….. 12
Muscle structure……………………………………………………………...… 12
Muscle contraction…………………………………………………….. 13
Muscle fiber type……………………………………………………………….…………….. 13
Summary…………………………………………………………………………..14
Muscle adaptations to exercise………………………………………………………..15
Neurological adaptations…………………………………………………………….15
Gene expression………………………………………………………………………….15
Hypertrophy……………………………………………………………………………..16
Fatigue/Fatigue resistance……………………………………………………………………16
Summary…………………………………………………………………………………….17
RelatedLiterature…………………………………………………………………………17
For hypothesis 1……………………..……………………………………………..….. 17
For hypothesis 2……………………………………………………………………………19
For hypothesis 3…………………………………………………………………………….19
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Chapter Three ……………………………………………………………………..…. 20
Subject selection…………………………………………………………………..21
Researchdesign………………………………………………………………………21
Resistance exercise…………………………………………………………………21
Cardiovascular exercise…………………………………………………………………21
Instrumentation…………………………………………………………………………22
Pre-test Protocol………………………………………..………………………………….. 22
Test Protocol………………………………………………………..………..………….. 23
Procedure…………….……………………………………………..……………………… 24
Post-test protocol……………………………………………………………………….25
Calculations…………………………………………………………………………….25
Data treatment…………………………………………………………………….25
Pilot data timeline……………………………………………………………………..25
Chapter Four ……………………………………………………………………..…. 31
Data and results………………………………………………………………………….….. 31
Figure 1. Arm volume and CVE……………………………………………… 31
Figure 2. Arm volume and RE ………………………………………………………….. 32
Figure 3. Arm volume comparison………………………………………..………….. 32
Chapter Five………………………………………………………………………….33
Discussion………………………………………………………………………………….33
Conclusion…………………………………………………………………………………36
References……………………………………………………………………………….36
Appendix 1- Informed Consent Form………………………………………….37
Appendix 2- Institutional review Board Approval…………………………..41
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The Effect of Cardiovascular Exercise on Reactive Hyperemia. Cody Hatfield Hanover College
Department of Kinesiology and Integrated Physiology
Sponsor: Dr. Bryant Stamford
Abstract
The purpose of this study was to investigate the impact of performing cardiovascular exercise
prior to resistance exercise on reactive hyperemia in the dominant arm. Resistance exercise is
known to “pump up” (reactive hyperemia) the exercised muscle. However, increased skin blood
flow associated with cardiovascular exercise could reduce this effect. It was hypothesized that
(1) arm volume will increase after each cardiovascular exercise or resistance exercise, and (2)
the net arm volume increase when cardiovascular exercise is performed prior to resistance
exercise will be lessened. This study was approved by the Hanover College Institutional Review
Board with regard to the use of human subjects.
Methods
Eight fitness trained male subjects volunteered to participate. Arm volume was measured using
a water displacement method, and measurements were taken after resistance exercise alone,
after cardiovascular exercise alone, and after resistance exercise with prior cardiovascular
exercise. The resistance exercise protocol consisted of a 20-repetition set of bicep curls using a
25-pound dumbbell weight, and the cardiovascular exercise protocol consisted of a 30-minute
treadmill walk/run at a constant heart rate of 130 bpm.
Results/Discussion
Observations from several arm volume measurement comparisons revealed that muscular
blood flow, as a result of resistance exercise, is restricted by increased skin blood flow due to a
thermoregulatory response brought on by prior cardiovascular exercise. This finding accepted
all hypothesis. The results suggest that performing cardiovascular exercise prior to resistance
exercise provides a negative impact on the effectiveness of resistance training, so performing
resistance exercise prior to cardiovascular exercise in the same workout is advised for achieving
the best possible outcome of a workout.
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The Effect of Cardiovascular Exercise on Reactive Hyperemia
Chapter 1
Introduction
When people go to the gym to work out, their workout plans usually contain some combination
of cardiovascular exercise and resistance exercise. Many individuals have differing opinions on
each exercise type, including pros and cons of both. It is widely accepted throughout the fitness
community that a workout becomes the most effective when both exercises are performed at
some point during the same workout. This brings up the question of which workout should be
done first? It would make logical sense for an individual to begin their workout with the
exercise that is least likely to negatively affect the remainder of their session.
Research has shown that when performing cardiovascular exercise prior to resistance exercise,
there is a conflict that arises regarding blood redistribution. Cardiovascular exercise elicits a
thermoregulatory response that increases the amount of skin blood flow throughout the body
in order to decrease the rising internal body temperature (1,5,10,11). Skin blood flow increase
is temperature-dependent, meaning that the body will continue to profuse excess blood to the
skin so long as the body temperature remains above homeostasis levels (1,5,10,11). Moreover,
a decrease in body temperature is necessary in order to decrease the amount of skin blood
flow. Sluggish blood redistribution occurs as a result (6,8).
When resistance exercise is performed after cardiovascular exercise, the cardiac demand of the
skeletal muscle increases (1,3,4,6,7,9). However, because the blood flow is still being redirected
to the skin in order to siphon off metabolic heat produced from the cardiovascular exercise,
there is less oxygenated blood available to be directed to the working muscle. This decrease in
blood flow results in less reactive hyperemia within the active muscle (3,12). In theory, less
reactive hyperemia in the muscle results in a less efficient resistance exercise workout. This
study investigated the effects that cardiovascular exercise has on the blood flow redistribution
to the working muscle during resistance exercise.
Statement of Purpose
To determine if prior cardiovascular exercise has a negative influence on reactive hyperemia in
the dominant arm following exhaustive resistance training.
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Significance of Study
Professional Significance:
Knowing the effects that cardiovascular exercise had on resistance training will help decipher
the ultimate question of: “How should you organize your workout routine to maximize the
benefits of both forms of exercise?” Of course, this will be specific to the workout goals of every
individual, but the ability to determine a blood flow hindrance to the working muscle post-
cardiovascular exercise could motivate the fitness community to model their workout plans to
fit the workout that provides the best results.
On a deeper level, this study can help examine the relationship between reactive hyperemia
and resistance exercise. The ability to recognize a decrease in reactive hyperemia after
resistance exercise with prior cardiovascular exercise has potential to show a negative impact in
regards to muscle building. The working muscle needs a certain amount of oxygen and
nutrients to fuel and repair itself after a lift. If that muscle does not receive all of those
nutrients, then it is concluded that it is not being nourished in such a way that promotes
maximal growth. In effect, cardiovascular exercise has a negative impact on resistance exercise.
Personal Significance
As an experienced weight lifter, I have often wondered if the workout I was performing was
giving me the best results possible. A personal exercise goal of mine is to lose fat while putting
on muscle. That would entail adding both aerobic exercise and weight training into my daily
regimen. I am curious to know if by “warming up” with aerobic exercise, I am actually hindering
my muscular gains by limiting the amount of blood flow to my working muscle. I am always
looking for ways to improve my workout, and I believe this study will be a good first step in
understanding how I should go about that.
Delimitations
This study was performed on 6 male subjects with a background in athletics. The independent
variable was cardiovascular exercise, and the dependent variable was the amount of reactive
hyperemia in the dominant bicep of the subject. To test each variable, each subject participated
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in a control and an experimental trial. The control trial consisted of a simple arm volume
measurement before and after a controlled set of bicep curls. The experimental trial had
essentially the same structure, however, moderate-intensity cardiovascular exercise was
performed prior to the set of bicep curls.
The underlying question of this study was: Does performing cardiovascular exercise prior to
resistance exercise result in a less efficient resistance workout? In order to answer this
question, the blood flow competition that occurs when cardiovascular exercise is performed
prior to resistance exercise was analyzed. The goal behind this method was to discover if a
blood flow deficiency in the skeletal muscle occurred after resistance exercise with prior
cardiovascular exercise.
If arm volume increased after performing exercise, it was attributed to reactive hyperemia.
Reactive hyperemia was then used as a measurement of workout efficiency. The more reactive
hyperemia that occurred, the more efficient the workout was concluded to be. If a resistance
workout was shown to produce less reactive hyperemia when cardiovascular exercise was
performed prior to, then that combination of exercises was determined to be less efficient.
Limitations
 Small sample size of subjects limits the external validity
 Only one experimental trial per subject
 Only testing males, particularly athletic males
 Only testing one specific form of cardiovascular exercise- running
 Only testing one specific form on resistance exercises- bicep curls
Assumptions
 All subjects did not previously exercise prior to testing
 Pipet cleaner apparatus was properly calibrated and yielded accurate measurements
 All subjects are able to perform 20 repetitions of a bicep curl with a 25-pound dumbbell
 Muscle volume increase is due to blood flow, and not any other external factors
 Subjects did not eat a heavy meal before participation
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Hypotheses
It was hypothesized that arm volume will….
1) Increase after resistance exercise alone
2) Increase after cardiovascular exercise alone
3) Increase less when cardiovascular exercise is performed prior to resistance exercise
Definition of Terms
1) Reactive Hyperemia- An increase in skeletal muscle blood volume following a brief
eclusion of the blood vessels due to muscular contraction.
2) Arteries- A vessel that carries Oxygenated blood from the heart to the rest of the body
3) Arterioles- Smaller diameter blood vessel that connects arteries to capillaries. Are
extremely flexible as to accommodate for proper vasoconstriction/dilation needs.
4) Capillaries- Smallest blood vessel. Has porous membrane that allows oxygen and other
nutrients to pass through into the cells.
5) Capillary Beds- End of the capillary where fluid exchange occurs. Oxygenated blood
becomes deoxygenated blood at this time.
6) Capillary exchange- Hydrostatic pressure (blood pressure) causes fluid to exit the porous
membrane of the capillary and supply nutrients to the surrounding cells. At the same
time, Osmotic pressure (solute gradient) pulls fluid back into the capillary beds due to
high solute concentration inside the capillary and high fluid concentration outside the
capillary. Once the fluid re-enters the capillary, it is deoxygenated.
7) Diffusion- The random movement of molecules from an area of high concentration to
low concentration
8) Pre-capillary Sphincters- Band of smooth muscle that adjusts blood flow into the
capillaries. Can open/close depending on the amount of oxygen needed in the particular
location
9) Venous return- Return of blood flow to the heart through the veins. Assisted by muscle
pumps, pressure gradients, and gravity.
10) Venules- small blood vessels that carry blood from the capillaries to the veins
11) Vasomotor Tone – The amount of tension on the arterial walls that requires an artery to
expand/contract. Affected by norepinephrine (constriction) and nitric oxide (dilation).
12) Norepinephrine- Released by adrenal gland and binds to alpha-receptors on blood
vessels that causes constriction.
13) Nitric Oxide- Produced in the body. Binds to beta-receptors on blood vessels and causes
vasodilation
14) Red Blood cell- Basic oxygenated blood cell. Carries oxygen and other nutrients all
throughout the body through arteries.
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15) Hemoglobin- Oxygen binding site in a red blood cell. This is how oxygen is able to be
carried by the red blood cell. It is a protein consisting of 2 alpha and 2 beta dimers and
includes four heme sites.
16) Cardiovascular Drift- The gradual, time-dependent change in several cardiac responses
as a result of prolonged exercise.
17) Motor Unit- A motor neuron and all the muscle fibers innervated by that single motor
neuron. Responds to an “all or none” manner to stimulus
18) Motor Unit Recruitment- The activation of additional motor units in order to accomplish
an increase in strength of muscular contraction.
19) Fast-Twitch Fibers- Muscle fibers that have a high glycolytic capacity and a low oxidative
capacity. Also referred to as “type 2 fibers”
20) Slow-Twitch Fibers- Muscle fibers that have a high oxidative capacity and a low
glycolytic capacity. Have a slow contractile speed, but shows excellent endurance to
repeated stimulus.
21) Thermogenesis- The the generation of heat as a result of metabolic reactions
22) Systolic Blood Pressure- The highest arterial pressure measured during a cardiac cycle
23) Diastolic Blood Pressure- Arterial blood pressure during diastole
24) Diastole- Period of filling the heart between contractions. Also known as the resting
phase of the heart
25) Systole- Portion of the cardiac cycle in which the ventricles are contracting
26) SA node- Specialized tissue located in the right atrium of the heart. It generates the
electrical impulse to initiate a heart beat.
27) Pulmonary Circuit- Refers to the portion of the cardiovascular system in which the blood
travels from the right ventricle of the heart into the lungs and back to the left atrium.
Blood becomes oxygenated at this stage.
28) Negative Feedback- Describes a response from a control system that reduces the size of
the stimulus.
Operationally Defined Terms
1) Water Displacement Apparatus- The tool used to measure arm volume via water
displacement. It is filled with water, and the arm is submerged up to a stopping point.
The measure of water increase in the tube can be simulated to suggest a change in
volume.
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Chapter 2
Background Research
Blood Flow
Blood flow through the body
The purpose behind blood flow is to transport critical oxygen and nutrients throughout
the body for the completion of many physiological processes necessary for life (6,7,8). To do
this, blood needs to be forced through the blood vessels and delivered to the tissues. The heart
acts as the pump that is the driving force behind blood circulation. The path that blood takes is
described as follows (6):
Blood begins in a deoxygenated form in the right atrium of the heart. From there, it is
pumped through the tricuspid valve into the right ventricle during a phase known as diastole, or
the refilling phase. Once the right ventricle is filled, it enters the systole phase, which is known
as the contractile phase. This is the phase in which the ventricles contract and force blood to
eject into one of two circuits. From the right ventricle, the blood then enters the pulmonary
circuit. The main goal of the pulmonary circuit is to re-oxygenate the blood, and it accomplishes
this through gas exchange that occurs in the alveoli. As the blood passes through the lungs, it
acquires oxygen and releases carbon dioxide to be later expired. This newly oxygenated blood
flows into the left atrium through the left pulmonary veins. The blood is then pumped through
the bicuspid valve into the left ventricle, once again entering the diastole phase. Once filled, the
left ventricle pumps the blood through the aortic valve and into the aorta to enter the systemic
circuit during systole. Once into the aorta, blood then flows through several large arteries that
branch out in all directions. As the arteries travel further from the heart, they eventually
become near-microscopic. These microscopic blood vessels are known as arterioles. The
arterioles are very flexible, and are suspect to various degrees of vasoconstriction and
vasodilation in order to accommodate for multiple blood pressures and volumes, depending on
the needs of the tissues in that area. Once through the arterioles, the blood flows through the
pre-capillary sphincters and into the capillaries, the smallest form of blood vessel in the body.
The capillaries are arranged into “beds” that perform capillary exchange, which is the method
by which the oxygen and nutrients are extracted from the blood and delivered to the tissues.
Once the oxygen and nutrients are delivered, the now-deoxygenated blood diffuses back into
the capillaries.
Blood flow back to the heart, or venous return, begins with the deoxygenated blood
sitting in the capillaries. From the capillaries, the blood is transported into small venous vessels
known as venules. Because venous return is not assisted, it calls for alternate mechanisms to
help force blood back to the heart. Those mechanisms include: pressure gradients, muscle
pumps, venous one-way valves, respiratory pumps, and gravity. Each of these mechanisms aid
the blood to flow from the microscopic venules and into the larger veins. The veins use the
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same venous return mechanisms to force blood up the inferior vena cava and back in to the
right atrium of the heart, back where the blood first began the circuit (6).
Capillary exchange
The main role of the capillaries is to transfer oxygen and other usable nutrients to
various body tissues. They perform this task through capillary exchange. The process begins
with the oxygenated blood being pumped into the capillary through the pre-capillary sphincter,
which opens when the tissue that it supplies is in need of more blood flow. Capillaries are
comprised of single layer epithelial cells, which makes them highly permeable to oxygen
molecules and other nutrients (6,8). These molecules then diffuse through the capillary wall
with the assistance of hydrostatic pressure, or the pressure applied by the heart pump. and into
the tissue, where they are metabolized. The waste fluid that did not contain nutrients is then
diffused back into the capillary via osmotic pressure, or the pressure created from a
concentration gradient. There is a low fluid concentration inside the capillary and a high fluid
concentration outside the capillaries, which drives the osmotic pressure to push the fluid back
into the capillary. This fluid is now the deoxygenated form of blood, which is pumped back to
the heart via venous return mechanisms in order to be re-oxygenated (6,8).
Blood flow redistribution during exercise
In order to supply the working muscles with more oxygen and nutrients needed for
exercise, it is necessary to increase the amount of blood flow that is being pumped to the
working area. To do this, there needs to be several physiological changes that take place. Most
notably, there needs to be an increase in cardiac output (6,8). The components of cardiac
output are heart rate and stroke volume. Increasing heart rate will increase the rate at which
newly oxygenated blood is pumped through the body, and increasing stroke volume will
increase the amount of blood that is pumped to the body with each contraction of the left
ventricle. However, increasing cardiac output only increases blood flow throughout the entire
body, not to the specific muscle group that are working to perform the exercise. In order to
channel the blood to a specific location, vasodilation of the blood vessels that supply the
muscle occurs, as well as vasoconstriction of blood vessels that are supplying less-active
portions of the body such as the liver and intestinal tract (1,3,6,8,9). Capillary sphincters also
need to be opened during exercise to allow for the blood to be diffused into the capillaries.
Vasomotor-tone occurs because the chemoreceptors in the working muscle will pick up an
acidity change due to the production of excess carbon dioxide during metabolism. These
chemoreceptors will then send messages to the cardiac control center of the brain, which will
remove the sympathetic stimulation to the blood vessels supplying the muscle, causing them to
vasodilate (1,3,6,8,9). The same signal will be sent to the blood vessels supplying the less-active
tissues in order to increase the sympathetic innervation and cause them to vasoconstrict. This
vasoconstriction of less-active tissues causes blood flow to be directed toward the most
accepting blood vessels: the blood vessels supplying the working muscles. The increased
amount of blood flow to the working muscle allows it to continue to produce energy for the
purpose of completing the exercise.
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The blood redistribution factor is rather impressive. Blood flow to the working muscle
can increase from 15-20% during rest to 80-85% during exercise. At the same time, blood flow
can decrease in a non-active organ such as the intestinal tract from 20-25% at rest to a mere 3-
5% during exercise (6). It displays the ability of the body to prioritize the physiological needs at
any given time.
Reactive hyperemia
Reactive hyperemia is a phenomenon that that occurs when skeletal muscle blood flow
overreacts due to the occlusion that occurs when a muscle contracts to 60% or more of its
maximal capacity. To elaborate, the blood vessels that supply the working muscle are being
squeezed and shut off by the force of the contracting muscle, thus incurring an inability to
supply the muscle with oxygen and nutrients. During this time, the metabolic rate continues to
increase, with continued insufficient blood flow. The body is receiving information that the
muscle is not receiving enough blood, so it acts to make to blood vessels that feed it vasodilate
maximally. These increases in blood vessel dilation are useless, however, until the muscular
contractions cease. Once the contractions cease, an excessive amount of blood surges into the
muscle, causing a hyperemia effect. This is the reasoning behind the “pump” that a weight lifter
receives after a set of weight training (12).
Thermoregulatory blood flow response.
When the body undergoes extensive cardiovascular exercise, a thermoregulatory
response occurs in reaction to the steadily increasing body temperature in order to keep the
body at homeostasis (1,5,10). During exercise, the body is burning a lot of energy through
metabolism. A side product of metabolism is heat. So, an increase in metabolism corresponds
with an increased internal body temperature. To maintain homeostasis during exercise, the
body works to eliminate as much excess heat as possible. From a blood flow perspective, the
thermoregulatory response to an increasing body temperature is to increase the amount of skin
blood flow (1,5,10). Increasing skin blood flow releases heat via convection. What this means is
the blood will carry with it heat from the core of the body, which will be above 98.6˚F, and carry
it to the skin, which is exposed to the surrounding environment. As long as the temperature of
the surrounding environment is less than the temperature of the blood, heat will transfer from
the hot blood to the cooler surrounding environment, causing heat to leave the body (6,8).
The increase in skin blood flow occurs via much of the same processes that increase
muscular blood flow during exercise. The blood vessels that supply the skin are ordered to
vasodilate by the removal of sympathetic innervation to the vessels that was causing them to
remain at a certain diameter. The vasodilation occurs in all of the skin blood vessels
surrounding the entire body. Similarly, the blood vessels that supply less-active areas of the
body are forced to vasodilate via increased sympathetic innervation (1,5,6,8,10). These areas
would include the liver, intestinal tract, kidneys, etc. Blood flow to the skin is temperature
dependent, meaning that the blood vessels that supply the skin will continue to be vasodilated
until the internal body temperature drops back to homeostasis (1,5,6,8,10). This is thought to
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contribute to sluggish blood redistribution to the rest of the body while the thermoregulatory
response is occurring.
Summary
Blood flow as well as blood flow redistribution are extremely important physiological
concepts that are pertinent to this study. Blood redistribution allows adequate blood flow to be
available to a working muscle during exercise. The thermoregulatory response to exercise is to
increase blood flow to the skin in order to expel heat from the body. Herein lies a blood flow
conflict between the thermoregulatory systemand the active muscle. When the
thermoregulatory response is activated, the increased skin blood flow causes poor blood
redistribution due to the temperature-dependent nature of the vasodilatory mechanisms in the
skin. The conflict occurs when the active muscle is not receiving an adequate amount of blood
flow because of the excess blood profusion to the skin. This conflict could result in
unsatisfactory results for the exercise; those unsatisfactory results amounting to a lesser
amount of reactive hyperemia in the working muscle upon the ceasing of contractions.
Skeletal Muscle Physiology
Muscle structure
Skeletal muscle is comprised of several different types of tissue. These include muscle
fibers, nerve tissue, blood, and connective tissue (6,7,8). To begin, there are three different
layers of connective tissue that surround a muscle. Those are (from outermost to innermost):
the epimysium, perimysium, and endomysium. The epimysium wraps around the entirety of the
muscle, binding the individual fiber bundles into larger. The perimysium surrounds the
individual bundles of muscle fibers called fascicles. Within that lies the bundles of each
individual muscle fiber. Those are surrounded by the endomysium. The arrangement of these
bundles of fibers gives a muscle a striated appearance (6,7,8).
There are two other types of muscle within the body that are quite different from
skeletal muscle. Those are cardiac and smooth muscle. Cardiac muscle fibers are much shorter
than that of skeletal muscle. Along with being shorter, the fibers of cardiac muscle are also
more tightly compacted due to the fact that each fiber is not separated by an endomysium as it
is in skeletal muscle. The lack of endomysium also accounts for the branched structure of the
cardiac muscle fibers. The most important difference between the two muscle types is that
cardiac muscle contains intercalated disks which transmit electrical impulses throughout the
entire heart. This indicates that the entire heart can be stimulated using just one action
potential. Skeletal muscle fibers are individually innervated, meaning that a different nerve
impulse has to be present for each fiber of an entire muscle in order to allow for simultaneous
contraction. This difference allows for the heart to contract automatically as compared to
voluntarily.
Smooth muscle is located within many organs and blood vessels, namely the arteries
that carry oxygenated blood. Like cardiac muscle, smooth muscle is not striated, meaning that
the individual muscle fibers are not wrapped in an endomysuim fascia. Also like cardiac muscle,
13
smooth muscle is able to contract automatically with a single nerve impulse. This allows them
to provide a multitude of unassisted functions such as vasomotor tone, opening/closing of pre-
capillary sphincters, and the swallowing of food as it moves down the trachea. The differences
in muscle types allow for each type to possess a specific function, each just as important as the
other.
The intercellular aspect of a skeletal muscle cell contains many of the same components
as a regular cell, except they are multinucleated, meaning they have multiple nuclei. Another
unique component of a muscle cell is the myofibrils. Myofibrils are numerous threadlike
structures that contain contractile proteins. The two main contractile proteins are called actin
and myosin, with myosin being designated the “thick” filament and actin the “thin” filament.
There are smaller proteins located within the actin filament called troponin and tropomyosin.
Myofibrils are divided up even further into small segments known as sarcomeres
separated by z-proteins. Myosin filaments are located on the A-band of the sarcomere and
actin are located on the I-band. The small portion of sarcomere in which the a-band and I-band
overlap is known as the H-zone. All of these small components of a muscle cell play critical roles
in the contractile process (6,7,8).
Muscle contraction
Muscular contraction is a complex process involving several contractile proteins and
energy production systems that results in the shortening of the myofibrils. A contraction begins
with a nerve impulse from the motor neuron. This nerve impulse becomes an action potential
that releases acetylcholine into the synaptic cleft of the neuromuscular junction. That
acetylcholine then binds to receptors located on the motor end plate which causes a
depolarization to occur inside the muscle fiber. When the depolarization reaches the
sarcoplasmic reticulum, calciumis released. That calciumdiffuses into the muscle to eventually
bind to troponin, which is the “trigger step” in the contractile process. When the calciumbinds
to troponin, it causes the troponin to rotate around the actin filament, bringing with it
tropomyosin, which exposes the actin binding site. Myosin, with attached ADP + Pi, then binds
to the actin binding site. The ADP + Pi is then released, causing the myosin to bend, bringing
with it the actin filament causing a shortening of the sarcomere. This act is called the power
stroke, and it is the primary motion behind a muscular contraction. ATP will bind to the myosin
head after the power stroke, causing it to detach fro the actin binding site. Once detached, ATP
is broken down into ADP + Pi, causing the myosin head to extend once more. The process will
repeat as long as calciumis present in the muscle fiber, leaving the actin binding site exposed
for more power strokes. The simultaneous shortening of all the sarcomeres in a muscle cause
the overall contraction, which is used to do move the body and do work (6,7,8).
Muscle fiber type
Muscles are categorized by differences in metabolism and contractile velocity (6,7,8).
There are three different types of fibers in regard to these variables. Type 1 muscle fibers are
known as slow twitch oxidative fibers. These muscles are primarily responsible for maintenance
of body posture and skeletal support, but are also the main contributors in high-endurance
14
exercise. Type 1 fibers have a very slow contractile velocity, which makes them perfect for
activities that involve long, slow contractions, such as distance running or cycling. Along with a
slow contractile velocity, type 1 fibers also contain a very high concentration of oxidative
enzymes which allow them to have a high capacity for aerobic metabolism. The ability of
aerobic metabolism to produce a far greater amount of ATP than anaerobic metabolism
(glycolysis) provides type 1 fibers with a very high resistance to fatigue (7). Type 1 muscle fibers,
for this reason, are considered oxygen dependent. If oxygen is not constantly available to these
muscle, then their ability to be fatigue-resistant wanes.
The second type of muscle fiber, type 2 fibers, are further broken up into type 2a and
type 2b fibers. Type 2a fibers are essentially opposite of type 1 in terms of contractile velocity
and metabolism mechanisms. They are known as fast-twitch glycolytic fibers in that aspect.
Type 2b fibers contract at a very high velocity, allowing them to produce significantly more
force than their type 1 counterparts (7). On the same note, type 2b fibers do not have a very
high capacity for aerobic metabolism, meaning that most of the ATP that type 2b fibers use
comes from glycolysis, a much more inefficient metabolism mechanism. The results of this
relatively low ATP production are that type 2b fibers cannot sustain their powerful contraction
over a long period of time. This makes them useful for a lot of athletes who have to have quick,
powerful reactions, such as a running back who has to cut sharply to avoid a defender, or a
basketball player who has to jump to get a rebound. A benefit of type 2b fibers is that, because
they do not have a very high capacity for aerobic metabolism, they are not as oxygen-
dependent as type 1 fibers (7). This makes them more practical in conditions where oxygen is
largely unavailable.
Type 2a fibers are known as fast-twitch oxidative glycolytic fibers (6,7,8). These type 2
fibers are considered hybrids of both type 1 and type 2b fibers in that they carry characteristics
relative to both. These fibers can rely on both aerobic (oxygen dependent) and anaerobic (non-
oxygen dependent) metabolism mechanisms to produce contractions. This is why they are
considered the “transition” or “intermediate” fibers between type 1 and 2b as a result of
training (7). Type 2a fibers have the high contractile velocity and power of type 2b, so they are
appropriate for activities similar to that of type 2b fibers. However, type 2a fibers can be
trained to increase their oxidative capacity in order to become more fatigue-resistant. This
ability makes them the most adaptable of the three fiber types.
Summary
Muscular structure and fiber type are crucial tokens of information to understand when
discussing overall muscular performance. Because this study is centered around the
performance of muscles during resistance training, it will be focusing mostly on type 1, slow
twitch glycolytic muscles. Because slow twitch muscles are highly aerobic in nature, they are
deemed oxygen-dependent. This means that slow-twitch muscles require a significantly greater
amount of blood flow profusion than a type 2 fiber. If there were to be a lesser amount of
blood flow post exercise (reactive hyperemia), then it could be concluded that the muscle was
not receiving as much oxygen as it could have, meaning that it could have performed more
15
work if given more blood flow. This added amount of work could be considered added muscle
contractions. However, if oxygen from the blood was not available, then the ATP is not being
produced from aerobic metabolism. The ATP then could not perform its designated function in
the contractile process, causing fatigue and eventual inability to contract. All of this information
is suggesting that a lesser amount of blood flow will negatively affect the muscular
performance during resistance exercise.
Muscle Adaptations to Exercise
Neurological adaptations
A good portion of the strength gains that occur through training, especially those gained
early on in the process, can be attributed to the ability of the body to recruit an increased
amount of motor neurons to the working area (6,7,8). The increased number of motor units
allows the muscle fiber to experience more action potentials, and thus more overall
contractions. Having more motor units also allows for a greater strength of contraction initially.
When more motor units are available for muscular innervation, there is a faster speed of
contraction. A faster speed of contraction enables the muscle to contract with more force per
contraction, thus increasing strength.
Biochemical changes occur in muscle that influence increased physiological responses to
exercise. Those changes would include: increase in feedback from chemoreceptors in the
muscle and increased sympathetic nervous system innervation (6,8). Increased chemoreceptor
feedback in the muscle allows for the muscle to respond to an increase in pH difference
quicker. Because a pH difference would normally occur due to the increased production of
carbon dioxide during the production of energy, a quicker response by the body would be to
increase blood flow to the area faster. An increase in blood flow would result in more essential
nutrients, as well as oxygen, being delivered faster, and this would decrease fatigue rate in the
muscle. Increased sympathetic innervation would allow for the blood vessels surrounding the
trained muscle to be more readily vasodilated, allowing for more muscle blood flow without
having to assemble a response from the cardiac control center of the brain.
Gene expression
Genetics play a crucial role in the way individuals respond to resistance training
stimulus. Every individual has a different genetic code derived from their DNA, which they
acquire from their parents. Because genetic code differs in every human, the responses to
resistance training differ from person to person as well. Gene expression is the activating of
specific sections of the genetic code that allow for the synthesis of various proteins. Each
individual has a multitude of different genes that either exacerbate or hinder the effects of
training. Thus, when those genes are activated via training stimulus, different proteins are
synthesized in order to both repair muscle tissue as well as cause it to grow, or hypertrophy.
The degree to which these proteins are synthesized is different for all individuals (6,8).
16
Hypertrophy
Resistance training consists of constantly overloading the muscles through the use of
heavy weights. This overloading causes the muscles to increase in mass and cross-sectional
area, a process known as hypertrophy (6,7,8). Satellite cells act to facilitate this muscle fiber
growth. Satellite cells are located on the outermost layer of a muscle cell, in between the
sarcolemma and basal lamina. These cells are activated when the muscle receives any form of
trauma, such as the trauma associated with the resistance training overload. They fuse to
damaged muscle cells and donate their nuclei, which aids in the regeneration of the cell as well
as signals for more contractile proteins to be produced. This binding of satellite cells and influx
of contractile proteins is the basis behind all muscle hypertrophy (6,7,8).
The proteins that are produced are known as growth factors, and can be in the form of
either hormones or cytokines. Three of the more important growth factors include insulin-like
growth factor (IGF), fibroblast growth factor (FGF), and hepatocyte growth factor (HGF). IGF is
secreted by the skeletal muscle and it regulates insulin metabolism, as well as stimulates
protein synthesis. IGF and FGF both act to proliferate, or multiply satellite cells, causing an
increase in the amount of satellite cells in the skeletal muscle. The more satellite cells that are
present, the more they can influence hypertrophy (6,7,8). HGF is a cytokine with a slightly
different function in the hypertrophy process. HGF helps activate the satellite cells and cause
them to migrate to injured muscle cells.
Hormones play an additional role in the hypertrophy of muscle cells. For example,
growth hormone (GH) is a hormone produced by the pituitary gland that stimulates IGF within
the skeletal muscle, adding to the satellite cell count, and overall hypertrophy (6,7,8). Similarly,
testosterone is another hormone; more specifically, a male sex hormone. It has an amplified
anabolic (muscle building) effect that is a major contributor to muscle hypertrophy, especially
in men.
Fatigue/Fatigue resistance
Fatigue is defined as an inability to maintain a power output or force during repeated
muscle contractions (6). From a neurological standpoint, fatigue sets in when a reduction of
motor unit firing frequency occurs. From a physical standpoint, fatigue begins when the H+
concentration increases in the muscle. When a muscle is trained, it can increase its ability to
resist fatigue from both the neurological and physical components. When a muscle is being
heavily trained using resistance exercise, the first physiological adaptation that occurs is the
increase of motor unit recruitment. An increase in the amount of motor units that are recruited
during a contraction will lead to a higher motor unit firing frequency. This would result in a
delay in the motor unit firing frequency decrease that causes fatigue, effectively increasing
fatigue resistance.
As resistance training continues over a long period of time, skeletal muscle hypertrophy
begins to occur. Because the muscle type configuration in a resistance trainer is largely type 1,
this means that a large portion of the trainer’s muscle has a high capacity for aerobic
metabolism. Aerobic metabolism combines both H+ions and oxygen to produce ATP. The larger
cross-sectional area that results from hypertrophy increases the mitochondrial density in the
17
muscle fiber, allowing for more aerobic metabolism sites to obtain the loose H+ ions and
convert them into useable energy. When this happens, the concentration of free H+ ions in the
muscle decreases exponentially, and fatigue takes longer to set in.
Summary
Muscular adaptations to resistance exercise are the prominent reasons for strength
increase in weight lifters. Because strength gain is one of the more popular goals surrounding
weight training, it can be used to determine the effectiveness of a particular workout. In
respect to this study, it can help in determining if resistance exercise is hindered when less
reactive hyperemia is present after the workout. While it may not have as much of an effect
regarding the neurological adaptations, blood flow does have a distinct impact on the
effectiveness of a muscle to build and increase strength. More blood flow would result in an
increase in delivery of hormones such as GH and testosterone; both of which show anabolic
effects in muscle. The muscle also needs to be able to repair itself after an overload. The
essential oxygen and nutrients that are carried in the blood provide means for the muscle to
repair itself, as well as to remove damaged muscle cells.
Related Literature
Hypothesis 1
Arm volume will increase after resistance exercise alone.
Supportive Research
1) George A Brooks and Thomas D. Fahey Exercise Physiology: Human
Bioenergetics and its Applicants. Ch.16 pg.337. 1984.
2) Dimitris Athanasopoulos, Zafeiris Louvaris, Evgenia Cherouveim, Vasilis
Andrianopoulos, Charis Roussos, Spyros Zakynthinos, Ioannis Vogiatzis.
Expiratory muscle loading increases intercostal muscle blood flow during leg
exercise in healthy humans. J. Appl. Physiol. 109, 388-395. 2010.
Because the first hypothesis was a universally accepted fact of resistance exercise, a
good reference to start with was simply the exercise physiology textbook (item 1). Within
chapter 16, it was mentioned that “During exercise there is a redistribution of blood from
inactive to active tissues.” The textbook went on to describe the mechanisms behind blood
redistribution to the working muscles, touching on important topics such as vasomotor tone
and the sympathetic innervation that affects it. “There is a progressive increase in the amount
of sympathetic vasomotor activity during exercise.” I believe all of the information learned
about blood redistribution learned from this chapter in the textbook really supports hypothesis
1 by reinforcing the idea that blood gets funneled to the portion of the body that most
18
desperately needs it. In the case of my study, the bicep muscle is undergoing near-maximal
resistance exercise. The intensity of this exercise is going to cause a large influx of blood after
the muscular contractions have ceased (reactive hyperemia), causing the overall arm volume to
increase as hypothesized.
The second article by Athanasopoulos and colleagues (item#2) really encompassed the
theme of blood redistribution to the working muscle. In an interesting study, the researchers
attempted to investigate the effects of respiratory resistance on blood flow to the intercostal
muscles during light exercise.
The experiment they conducted involved a subject performing light exercise on a cycle
ergometer during two trials: one with and one without respiratory resistance. Blood flow to
both the quadriceps muscle and the intercostal muscles were measured via blood
plethsmography.
The principle discovery that was found from this study was that without respiratory
resistance, blood flow initially increased in the quadriceps. However, once respiratory
resistance was factored into the next trial, blood flow started to slowly decrease in the
quadriceps and increase in the intercostal muscles. Because the same amount of exercise was
being performed in each of the trials, the explanation could not come from the suggestion that
the exercise became easier over time.
The actual findings were based in the realm of blood redistribution. Blood is going to be
redistributed to the area that most desperately needs it. More often than not, that area is going
to be the muscle or muscle group that is performing the most work, thus needs the most
oxygen and nutrients to perform that work. During the first trial of this study, where there was
not respiratory resistance and the subject was only performing light cardiovascular exercise on
a cycle ergometer, the only muscle group that was working was the quadriceps. Naturally, there
was shown to be an increase in blood flow to the quadriceps during this time because that
muscle group needed the blood the most. During the second trial, when respiratory resistance
was introduced, there started to be a shift in blood flow redistribution from the quadriceps to
the intercostal muscles. The reasoning behind this was because once the respiratory resistance
was added, the intercostal muscles had to work extra hard in order to force air through the
respiratory tract. So hard, in fact, that their work output overpowered that of the quadriceps,
causing blood flow to redirect to the intercostal muscles.
The ability of this study by Athanasopoulos and colleagues to relate comes from the
proof that is displayed of blood redistribution to the hardest working muscle. It directly
provides evidence that supports hypothesis 1 by reinforcing the blood redistribution factor that
influences the volume of working muscles.
19
Hypothesis 2
Arm volume will increase after cardiovascular exercise only.
Supporting literature
1) Christensen, E.H., Nielson, M., and Hannisdahl, B., Investigations of the circulation in
the skin at beginning of muscular work. Acta physiol. Scand. 4, 162-170. 1942.
The purpose behind the study was to investigate the participation of the skin as a
vasoconstrictive mechanism of blood redistribution at the beginning of muscular work. The
protocol consisted of the measurement of skin blood flow in the finger during light
cardiovascular exercise using Burton’s plethysmographic method. One subject participated in
this study and endured four trials of cardiovascular exercise at work outputs ranging from 360-
1260mkg/min.
The study found that there was a distinct negative spike in skin blood flow within the
first two minutes of exercise at all work outputs. This negative spike gradually increased over
the course of the next 5 minutes, and surpassed that of the resting skin blood flow after ten
minutes of exercise. This pattern was repeated during all four work outputs, showing
remarkable consistency. As evidenced by the initial decrease in skin blood flow, it was shown
that the skin does participate in the vasoconstrictive mechanisms of blood redistribution at the
beginning of muscular work. However, the overall increase in skin blood flow that was observed
over the entire course of the 22-minute exercise addressed another interesting point. The
thermoregulatory systemdemands a relatively large amount of blood flow in order to release
heat buildup from the metabolic processes that take place during cardiovascular exercise. This
would require a shift in blood flow redistribution from the active muscles to the skin. The
redistribution can be significant enough, as it was shown to be in the results of this study, to
increase the skin blood flow to more than that of resting values. When skin blood flow is higher
than resting values, there is more blood in the area than there normally would be during rest.
That revelation leads to the accepting of hypothesis 2, that arm volume will increase after
cardiovascular exercise alone.
Hypothesis 3
Arm volume will increase less after resistance exercise when prior cardiovascular exercise is
performed.
Supporting literature
1) Johnson J.M., and Rowell L.B. Forearm skin and muscle vascular responses to
prolonged leg exercise in man. J. Appl. Physiol. 39. 920-924. 1975.
2) Bishop J.M., Donald S., Taylor S.H., and Wormald P.N. The blood flow in the human
arm during supine leg exercise. J. Physiol. 137, 294-308. 1957
20
The first study performed by Johnson and Rowell (item 1), had the purpose of
investigating the muscular, as well as skin vascular responses to prolonged cardiovascular
exercise in man. Their testing protocol involved 8 healthy adults performing 60 minutes of
prolonged moderate intensity exercise on a cycle ergometer. Both their forearm muscle blood
flow, as well as their forearm skin blood flow were measured throughout the entire 60 minutes.
The results showed a progressive increase in overall forearm blood flow. However, there
was revealed to be a slight decrease in muscular blood flow, meaning that the entire volume of
blood flow increase originated from skin blood flow. This was due to the relative inactivity of
the forearm muscle and the increased thermoregulatory response that occurred because of the
excessive metabolic heat produced from the prolonged exercise. These results suggest that the
cardiovascular exercise caused a very high response concerning skin blood flow presumably
throughout the entire body, not just the forearm. Because this is the case, it supports
hypothesis 3 that arm volume will increase less when cardiovascular exercise is performed prior
to resistance exercise.
It takes a significant amount of blood to profuse to the entirety of the skin because the
skin covers every inch of the body. The readings that came from the forearm only are merely a
fraction of the actual amount of skin blood flow occurring due to the thermoregulatory
response of the exercise. The other 90% of the blood is trapped in the skin at other areas of the
body, meaning that only a fraction of the overall blood volume is available to be redistributed
to the muscle during resistance exercise post-cardiovascular exercise. This still shows arm
volume increase, but not nearly to the degree that it would if that thermoregulatory response
was not active.
The second study performed by Bishop, Donald, and Wormald was very similar in
methodology, except the second study performed the cardiovascular work while in the supine
position. All of the same results were reached: increased amount of skin blood flow coupled
with a slight decrease in muscle blood flow, attributing to a slight overall arm blood volume
increase. The study merely suggested that position of the body relative to gravitational venous
return showed no additional effect in blood redistribution. The body was able to
overcompensate for this condition regardless of the natural tendency of the blood to move
with gravity. This study continues to support hypothesis 3 by demonstrating the negative effect
that skin blood flow during a thermoregulatory response has on overall blood flow
redistribution.
Chapter 3
The purpose of this study was to determine if prior cardiovascular exercise had a
negative effect on reactive hyperemia in the dominant arm. An in-depth description of the
subject selection, research design, instruments, procedures, and pilot data will be discussed in
the following chapter.
21
Subject selection
6 male subjects participated in this study. They were all Hanover College students
between the ages of 20-22. Each subject was determined to be physically fit; either
participating or have had participated in Hanover College athletics. Physical fitness as well as
experience in a weight room environment were taken into account when selecting subjects
because it was important that the subjects be physically capable of completing the exercise
procedures that were asked of them for the purposes of this study. Subjects were ultimately
chosen vi willingness to participate.
Research design
The subjects were to participate in two trials: a control trial as well as an experimental
trial. For the control trial, they were asked to gather a baseline arm volume, then perform the
resistance exercise protocol and observe the change in arm volume after the resistance
exercise. The experimental trial began with a similar protocol of that of the control protocol.
The subject would first measure their baseline arm volume, then engage in the cardiovascular
exercise protocol followed immediately by another arm volume measurement. The subject
would then follow with a performance of the resistance exercise protocol once more followed
by a final arm volume measurement. Overall net arm volume change from resting to post-
resistance exercise was measured and compared in both protocols. Each trial was performed on
subsequent days.
Resistance exercise
Each subject was asked to complete a resistance exercise protocol consisting of a 20-
repetition bicep curl exercise using a 25-pound dumbbell weight. A smaller weight would be
provided in the 20-repetition goal could not be met. This is important because repetitions are
the key to this portion of the exercise. The subjects are supposed to be taking themselves to an
exhaustive state, thus initiating the reactive hyperemia response. This response is not possible
if only mild or moderate-intensity resistance exercise is performed. The subject was to only use
their dominant arm.
Cardiovascular exercise
Each subject was asked to complete a cardiovascular exercise protocol consisting of 30
minutes of moderate-intensity exercise on a treadmill. The goal was to maintain a work output
consistent with a target heart rate of 130 beats per minute for each subject. This goal would be
specific for each subject, as they were each their own control with regard to fitness level and
task specificity. This specificity was controlled by adjusting the speed and incline of the
treadmill to accommodate the fitness levels of each subject. By using this method, it was
possible to maintain a constant work output across the subject pool.
22
Instrumentation
Arm volume measurement
A modified water pipet apparatus was used to measure arm volume via water
displacement. This equipment was self-calibrated and modified for this study alone.
Resistance exercise
(1) 25-pound dumbbell weight was used to administer the resistance exercise portion of
the study. A smaller weight would be available if any subject would not complete the entire
protocol with the 25-pound weight.
Cardiovascular Exercise
A Fitness T610 treadmill, Polar FS3 heart rate monitor, and stopwatch were required to
administer the cardiovascular exercise portion of the study.
Pre-Test protocol
Control trial
(a) Subjects were asked to wear appropriate clothing. Such clothing would include a
sleeveless shirt, or possibly no shirt if preferable. The reasoning behind this would be
because the subject would be completely immersing their arm in the water pipet filled
with water. Having no sleeves would be for the benefit of accurate measurements and
of the subject to not get their shirts wet.
(b) Subjects were asked to not participate in any excessive physical activity at least 2 hours
prior to participating in this trial. This is to ensure the accuracy and validity of the initial
baseline measurements.
Experimental
(a) Subjects were asked to wear appropriate clothing. Such clothing would include a
sleeveless shirt, or possibly no shirt if preferable. The reasoning behind this would be
because the subject would be completely immersing their arm in the water pipet filled
with water. Having no sleeves would be for the benefit of accurate measurements and
of the subject to not get their shirts wet.
23
(b) Subjects were asked to being a sweatshirt with them to use during the cardiovascular
exercise protocol. This was to in maximize the thermoregulatory response by the body
in order to show maximal skin blood flow values
(c) Subjects were asked to not participate in any excessive physical activity at least 2 hours
prior to participating in this trial. This is to ensure the accuracy and validity of the initial
baseline measurements
Test Protocol
Each trial consisted of several arm volume measurements using the modified water
pipette apparatus. Every arm volume measurement was obtained using the following
procedure:
1) The water pipette apparatus was filled with water all the way to the 230mm mark on
the small measuring tape located at the top of the cylinder.
2) A few drops of blue food coloring were added to the water to ensure clear visibility
during measurement.
3) The subject was marked with a dry-erase marker with a line just below the inferior
portion of their dominant deltoid muscle. This would indicate how far the subject should
insert their arm into the water pipette cylinder.
4) The subject would then insert their dominant arm all the way into the cylinder, stopping
on the mark that was mentioned in the previous step.
5) Displacement of water was measured from before arm insertion to after arm insertion.
All water levels started at 230mm. Water displacement was measured to the closest
millimeter as designated by the white measuring tape adhered to the upper portion of
the cylinder.
24
Procedures
Control trial
1) The subject was asked to change into proper clothing, or to remove their shirt upon
arrival in the physiology lab at Hanover College.
2) The subject rested for 15 minutes in a sitting position.
3) A resting arm volume was obtained using the water pipette apparatus
4) Dry off
5) The subject was then asked to complete the resistance exercise protocol as
instructed
6) Arm volume was measured again 5 seconds after the completion of the resistance
exercise protocol.
7) Dry off
8) Changes in arm volume were recorded and the subject was finished
Experimental trial
1) The subject was asked to change into proper clothing, or to remove their shirt upon
arrival in the physiology lab at Hanover College.
2) The subject rested for 15 minutes in a sitting position
3) A resting arm volume was obtained using the water pipette apparatus
4) Dry off
5) The subject then put on the sweatshirt that they were instructed to bring with them
6) The subject was then asked to complete the cardiovascular exercise protocol as
instructed
7) Arm volume was measured again 5 seconds after completion of the cardiovascular
exercise protocol.
8) Dry off
9) Changes in arm volume were recorded
10) The subject was asked to then proceed with the resistance exercise protocol once
more
11) Arm volume was measured one final time 5 seconds after the completion of the
resistance exercise protocol.
12) Dry off
13) Changes in arm volume were recorded and the subject was finished
25
Post-Test protocol
Upon conclusion of each trial, the subject was encouraged to drink plenty of fluids as to
rehydrate themselves after the participation in exercise. The subject was to report any feelings
of nausea or fatigue to the instructor. All wastes were disposed of and the water pipette was
properly drained according to the instruction manual. All supplies were stored and the lights in
the lab were turned off.
Calculations
The water pipette apparatus was fitted with a small measuring tape that was adhered to
the outside of the cylinder towards the top. This tape read millimeters of water displacement.
Because the pipette was calibrated so that 1 centimeter of water increase was the equivalent of
200 milliliters of overall volume increase in the arm, the units had to be converted from
millimeters to centimeters. Then that centimeter value could be multiplied by 200 in order to
reveal the total amount of volume that was displaced. The following equation was used for this
process:
(initial volume (mm)) – (final volume (mm)) x 200 = Arm Volume (ml)
10
the final arm volume measurement was converted from milliliters to liters for data presentation
purposes, as well as simplicity purposes.
Data Treatment
The data obtained in this study was organized by category into: Arm volume at rest, arm
volume after resistance exercise alone, arm volume after cardiovascular exercise alone, and net
increase. These values were statistically analyzed to calculate percent increases, averages, and
overall volume change.
Pilot Data Timeline
Data session 1
The pilot data for this study began in modest fashion. The goal of the first session was to
simply determine whether or not the measuring mechanism (the water pipette apparatus) was
an accurate and reliable source of measurement data. To do this, there needed to be at least
two arm volume measurements taken in succession of one another. Before this could take
place, however, the optimal base volume of water in the pipette had to be determined. A trial
and error process soon began in this calibration method. The overall volume of water in the
pipette had to be set to a very specific level in order for the calibrations from previous uses to
work. The first volume of water added was 8 liters, which proved to be an insufficient amount
because the subject was unable to fully submerge the arm to the designated stopping point.
26
The water was dumped out and re-measured, this time to read 10 liters. This worked well for
the needs of the study, as the subject was able to comfortably submerge their entre arm
without causing the pipette cleaner to overflow. After this point, the decision was made to
begin trials with the baseline volume of 10 liters.
The protocol for this data was simple. The subject was asked to measure the volume of
both their dominant and non-dominant arm for several trials, with one trial occurring each day.
The goal was to stop the trials once two successive measurements for each arm were taken. If
this occurred, the measurement method was considered reliable. If this did not occur within
the framework of 5 trials, then the apparatus would have been deemed unreliable.
Figure 1. Dominant and non-dominant arm volume measurement comparison.
This pilot data was performed in order to prove the modified water pipette apparatus as an
accurate and reliable piece of equipment. The dominant and non-dominant arms of the subject
were measured twice over the period of two days. The goal was to record similar results for
both trials. This would show consistency and reliability. As can be seen in the figures above, the
dominant arm in both trials was larger than the non-dominant arm. The values possessed a
relatively small spread as well, with the dominant arm ranging from 3.34L to 3.36L and the non-
dominant arm ranging from 3.24 to 3.28. These values allowed the researcher to move on with
their study with full confidence in the measurement equipment that was being used.
Data session 2
3.34
3.24
3.2
3.22
3.24
3.26
3.28
3.3
3.32
3.34
3.36
3.38
Dominant Non-Dominant
Volume(L)
Trial 1
3.36
3.28
3.2
3.22
3.24
3.26
3.28
3.3
3.32
3.34
3.36
3.38
Dominant Non-Dominant
Volume(L)
Trial 2
27
The purpose behind gathering this data was to test hypothesis 2. It was hypothesized
that arm volume will increase when resistance exercise is performed. This was an important
session of pilot data because it provided solid parameters on which to base the control protocol
that would be used for actual data collection later in the study. It also allowed for the
measurement of reactive hyperemia in the bicep to be recorded and tested for . During this
session, the subject was asked to measure their arm volume at rest to achieve a baseline
measurement. After that they were asked to perform a set of 20 dumbbell curls with a 25-
pound weight. The goal with these repetitions and weight was to maximally exhaust the
subject, providing the muscle with the maximum amount of reactive hyperemia as possible.
Figure 2. Arm volume at rest and after performing the resistance exercise protocol.
These results display the change in arm volume from rest to after the performance of the
resistance exercise protocol. The goal behind this data is to test hypothesis #1: arm volume will
increase after resistance exercise alone. The hypothesis was accepted here, as there is a clear
increase in arm volume from 3.68L at resting to 3.80L after resistance exercise. The increase
was attributed to reactive hyperemia that occurred as a result of the near-maximal bicep curl
exercise performed.
Data session 3
3.68
3.8
3.62
3.64
3.66
3.68
3.7
3.72
3.74
3.76
3.78
3.8
3.82
Rest After RE
Arm Volume after ResistanceExercise
Volume (L)
28
This session was similar to that of the second data session in that change in arm volume
was to be measured. Except in this pilot data, the second arm measurement was taken after
cardiovascular exercise. This data allowed for the measurement of the thermoregulatory blood
flow response that takes place after the performance of prolonged exercise. The subject was
asked to gather another baseline measurement upon arrival. Then they participated in 30
minutes of moderate cardiovascular exercise on a treadmill with a work output of 130 bpm. The
arm volume change was measured, and that change was attributed to the amount of increased
skin blood flow to the arm as a result of a thermoregulatory response.
Figure 3. Arm volume at rest and after performing the cardiovascular exercise protocol.
These results display the changes that occurred in arm volume from rest to after the
cardiovascular exercise protocol. The goal here was to test hypothesis #2: Arm volume will
increase after cardiovascular exercise alone. The hypothesis was accepted here due to the clear
increase in arm volume that is shown above in figure 3. There was an increase from 3.7L at
resting to 7.76L after cardiovascular exercise. The increase was due to the increased amount of
skin blood flow present due to the increased thermoregulatory response of the body.
Data session 4
This data session was a bit trickier because this was s simulation of the entire
experimental protocol. This required a lot of extra data collection. Data session 2 was repeated
to determine the arm volume change due to resistance exercise only. To explain the
experimental protocol, first the subject would acquire a baseline arm volume measurement.
Then they would perform the cardiovascular exercise as explained in data session 3. Arm
3.7
3.76
3.62
3.64
3.66
3.68
3.7
3.72
3.74
3.76
3.78
3.8
3.82
Rest After CVE
Volume (L)
29
volume change was then measured to incorporate the thermoregulatory response into the
overall reactive hyperemia acquired at the end of the protocol. After all, skin blood flow
affected overall arm volume, but was not included in the reactive hyperemia measurement.
After the cardiovascular exercise protocol, the subject underwent the resistance exercise
protocol. Arm volume was measured afterwards to determine the overall net change in volume
that occurred over the entire process. That net arm volume change was determined to be the
overall reactive hyperemia. This data session was intriguing because it shed light on the impact
that the thermoregulatory response had on the overall amount of reactive hyperemia. The
amount of arm volume increase after cardiovascular exercise was subtracted from the arm
volume measurement at the end, leaving the difference to be the amount of reactive
hyperemia present after the resistance exercise.
Figure 4. (left) arm volume at rest and after resistance exercise alone. (right) arm volume
measurements throughout entire procedure. Arm volumes taken at rest, after cardiovascular
exercise alone, and after the following resistance exercise.
This pilot data was used to test out hypothesis #3: Arm volume will increase less when
cardiovascular exercise is performed prior to resistance exercise. The hypothesis was accepted,
as there was less of an increase in arm volume during the experimental trial, where
cardiovascular exercise was performed prior to resistance exercise, than in the control trial,
where only resistance exercise was performed. The control trial displayed a net increase in arm
volume of 0.07L while the experimental trial displayed a net increase of 0.04L. The middle bar
on the experimental trial graph represents the change in arm volume from rest to after
cardiovascular exercise alone. It is included to show the percentage of arm volume increase
that is strictly skin blood volume increase.
Data session 5
3.64
3.71
3.6
3.65
3.7
3.75
3.8
Rest After RE
Control Trial
Volume (L)
3.72
3.74
3.76
3.6
3.65
3.7
3.75
3.8
Rest After CVE After CVE + RE
Experimental Trial
Volume (L)
30
This data session was performed in order to answer a question that was brought up
regarding the possible effect of water temperature on the vasodillatory mechanisms involved in
reactive hyperemia. The preceding notion was that a colder water temperature might have a
vasoconstrictive effect on the arm post-exercise, and that warm water may exacerbate the
vasodillatory effects. In order to test this, additional arm volume measurements were taken at
rest in water at 22˚C, 30˚C, and 40˚C. Those temperatures were used because of the
temperature limits provided by the tap water in the physiology lab The goal was to test for any
arm volume differences across the range of water temperatures. Any differences would
indicate that an additional effect was being added by the water used to measure the arm. The
results showed no volume changes in any of the temperature trials, indicating that water had
no effect on the vasodilatory mechanisms in the arm. The conclusion was that the arm is only
present in the water for a duration of approximately 15 seconds before being removed again.
This is because it does not take long for the arm to be measured by the researcher, so to have
the arm in the water for any additional time would be considered time wasted.
Figure 5. Arm volume compared in three different water temperatures.
This pilot data was used to answer the question of whether or not water temperature has any
added effects on the vasodillatory mechanisms in the arm. The arm volume at rest was
measured at temperatures of 22˚C, 30˚C, and 40˚C, presenting a wide range of temperatures to
test. The arm volume remained constant at 3.68 liters throughout each trial. These results
indicated no additional effect on arm volume provided by water temperature.
3.68 3.68 3.68
0
1
2
3
4
22℃ 30℃ 40℃
Volume (L)
Volume (L)
31
Chapter 4
Data and Results
Figure 1 displays an average arm volume increase of 0.04L when cardiovascular exercise was
introduced to the subjects. This increase was calculated from an average resting value gathered
from 8 different male subjects. The increase was deemed significant with a corresponding P
value of <0.05 derived from a standard T-test.
Hypothesis 1: Arm volume will increase after cardiovascular exercise alone – Accepted
3.42
3.46
3.4
3.45
3.5
Rest After CVE
Arm Volume and CVE
Volume (L)
Figure 1. Arm volume change fromrestingvalues to after cardiovascular exercise was introduced. Data shown represents the
average arm volume measurements of 8 subjects.
32
Figure 2. Arm volume change from resting values to after resistance exercise was introduced. Data shown represents the
average arm volume measurements of 8 subjects.
Figure 2 displays an average arm volume increase of 0.14L when resistance exercise was
introduced to the subjects. This increase was calculated from an average resting value gathered
form 8 different male subjects. The increase was deemed significant with a corresponding P
value of <0.05 derived from a standard T-test.
Hypothesis 2: Arm volume will increase after resistance exercise alone- Accepted
Figure 3. Difference between overall net changes in arm volume. The left bar represents the net change in arm volume in each
subject when strictlyresistance was performed. The right bar represents the overall net change in arm volume when both
cardiovascular and resistance exercise were performed. The data shown represents the average arm volume measurements of 8
subjects.
3.37
3.51
3.3
3.35
3.4
3.45
3.5
3.55
Rest After RE
Arm Volume and RE
Volume (L)
0.15
0.13
0.05
0.1
0.15
RE CVE + RE
Arm volume comparision
between RE and RE=
Net Volume Change (L)
33
Figure 3 displays a decrease in overall net arm volume change of 0.02L between when only
resistance exercise was performed and when both resistance and cardiovascular exercise was
performed. The change for resistance exercise alone was deemed significant with a
corresponding P value of <0.05, while the change for resistance and cardiovascular exercise was
deemed insignificant with a corresponding P value of >0.05. Both P values were derived from a
standard T-test.
Hypothesis 3: Arm volume will increase less after resistance exercise when prior cardiovascular
exercise is performed- Accepted
Chapter 5
Discussion
Why does arm volume increase when cardiovascular exercise is performed?
Increase in arm volume of any sort is described in this study as an increase in blood flow to the
specified area, more specifically, the dominant arm of the subject. The increase in blood flow to
the arm during this portion of the study can be attributed to the increased thermoregulatory
response from the body as a result of the cardiovascular exercise (1,5,10). When the body
undergoes cardiovascular exercise for any elongated period of time, it demands a high level of
metabolic activity. The increase in metabolic activity creates a buildup of heat inside the body,
causing the core temperature to increase to above homeostasis (1,5,10). The body is designed
to maintain a constant core temperature in order to regulate several bodily processes correctly,
so there are natural responses in place within the body that allow it to release any excess heat.
The first of these responses is to increase the amount of blood flow to the skin. When blood is
sent to the skin, it carries with it the excess heat from the core of the body. This extra heat is
then released into the environment surrounding the body via convection where the hot blood
releases the heat into the cooler surrounding environment, lowering the temperature of the
body. This process will continue as long as there is metabolic heat buildup (6,8).
The mechanism behind this blood redistribution to the skin is an elegant one. Once metabolic
heat begins to build up, the blood vessels that supply the skin are ordered to vasodilate by the
removal of sympathetic innervation to the vessels that was causing them to remain at a certain
diameter. The vasodilation occurs in all of the skin blood vessels surrounding the entire body.
Similarly, the blood vessels that supply less-active areas of the body are forced to vasodilate via
increased sympathetic innervation (1,5,6,8,10). These areas would include the liver, intestinal
tract, kidneys, etc. The vasodilation of the skin blood vessels along with the vasoconstriction of
blood vessels in the lesser-utilized areas of the body combine to force blood into the skin and
34
remove heat. The increased amount of skin blood flow as a result of the thermoregulatory
response of the body in what decidedly caused the increase in arm volume of the subjects
during this phase of the study.
Why does arm volume increase when resistance exercise is performed?
Arm volume increase due to resistance exercise is directly attributed to the effects of reactive
hyperemia that occur during such activity. The process of reactive hyperemia begins with a
strong muscular contraction that is at least 60% of maximal capacity of the muscle in question.
When the contraction is initiated, the blood vessels that supply the muscle become occluded by
the muscle compressing against the skin. The occlusion denies the muscle of blood flow,
causing it to starve for essential oxygen and other nutrients that it needs to continue to
contract. However, the contractions continue and the muscle is consuming a lot of metabolic
energy. The increase in metabolic output causes the body to vasodilate the blood vessels that
feed the muscle in order to supply it with more blood flow to aid the desire for oxygen.
Adversely, the blood vessels continue to be occluded by the muscle and it continues to be
denied blood flow. This negative feedback loop of vasodilation as a result of metabolic demand
from the muscle continues, causing a large amount of blood to be trapped in the vessel. Once
the muscle relaxes, all the blood that had been previously detained by the blood vessel
occlusion now rushes into the muscle, causing an exponential increase in the amount of blood
in the muscle capillaries. This large increase in blood volume due to the hyperemic effect of
resistance exercise is the direct cause of the overall increased arm volume of the subjects
during this phase of the study (12).
The mechanism behind muscular blood redistribution is relatively similar to that of skin blood
redistribution. In order to channel the blood to the specific muscle, vasodilation of the blood
vessels that supply the muscle occurs, as well as vasoconstriction of blood vessels that are
supplying less-active portions of the body such as the liver and intestinal tract (1,3,6,8,9).
Capillary sphincters also need to be opened during exercise to allow for the blood to be
diffused into the capillaries. Vasomotor-tone occurs because the chemoreceptors in the
working muscle will pick up an acidity change due to the production of excess carbon dioxide
during metabolism. These chemoreceptors will then send messages to the cardiac control
center of the brain, which will remove the sympathetic stimulation to the blood vessels
supplying the muscle, causing them to vasodilate (1,3,6,8,9). The same signal will be sent to the
blood vessels supplying the less-active tissues in order to increase the sympathetic innervation
and cause them to vasoconstrict. This vasoconstriction of less-active tissues causes blood flow
to be directed toward the most accepting blood vessels: the blood vessels supplying the
working muscle.
Why does arm volume increase less when cardiovascular exercise is performed prior to
resistance exercise?
The introduction of cardiovascular exercise prior to performing resistance exercise displayed a
particularly interesting situation involving two separate, yet competing influences on blood
35
redistribution within the body. The two influences were that of thermoregulatory, as well as
muscular blood redistribution. The competition ensues when the skin blood flow that occurs
due to the thermoregulatory response of cardiovascular exercise deducts from the overall
blood volume available to be redistributed to the working muscle during resistance exercise.
This occurs because of the temperature-dependent nature of skin blood flow. To elaborate, the
vasodilatory mechanisms that allow for increased skin blood flow in instances of high metabolic
heat production will stay activated until the internal core temperature of the body decreases
back to homeostasis (1,5,6,8,10). Because the exercise protocols were performed within
minutes of each other, the body had not yet had time to release all the heat necessary to
reduce the body temperature of the subject back to homeostasis. This caused the amount of
skin blood flow to remain high, while simultaneously denying the working muscle (bicep) of the
maximal amount of blood flow possible. These phenomena combined to display an overall
lower average arm volume per subject when cardiovascular exercise was performed prior to
resistance exercise as opposed to performing resistance exercise only.
Skin blood flow shows sluggish redistribution due to several factors. The first of such factors is
that skin blood flow occurs throughout the entirety of the skin, not just in the area that is being
worked. During extensive cardiovascular exercise, the body works to maximize heat loss in any
way it can. The best way for this to occur is to increase skin blood flow to as much of the
external skin cells as it can. The more heat-carrying blood that is received by the skin, the more
heat that can be lost through convection. Moreover, if the blood moves through the skin too
quickly, it will retain some of the heat that could be lost. This is why blood tends to linger in the
skin longer than usual; in order to release all the excess heat that it can before returning to the
circulatory systemto cycle back through the process. This lingering effect can be described in
the following figure:
The left diagram displays the maximizing effect that results from the collective vasoconstriction
of the skin blood vessels in correspondence with the lingering blood in the capillary beds of the
skin. The end result of this action is the release of substantially more heat than is pictured in
the right diagram, which displays the result of a lack of skin blood flow. Speaking in strictly
thermoregulatory terms, the left diagram describes an extreme advantage in heat loss
compared to the right diagram. In relevance to the study, however, it can be seen as a huge
disadvantage. The lingering effect of the blood in the skin capillary beds significantly hinders
36
the ability of the body to recirculate that blood to be used for other purposes. Specifically, to be
used as a constructive response to the overloaded muscle undergoing resistance exercise
(1,5,6,8,10).
In summary, there was a significantly less amount of blood flow available to the working muscle
during resistance exercise when prior cardiovascular exercise was performed. This resulted in a
less effective resistance exercise workout. Blood flow is the key to the effectiveness of
resistance exercise. This is because the purpose of resistance exercise is to overload the muscle
and cause it to make a positive change. This change is usually aimed towards hypertrophy, or
increase in the size of the muscle. In response to this overload, the body provides a constructive
response (blood flow) that is used by the muscle for repair and enhance itself. If that
constructive response is limited by outside factors (thermoregulatory response), then it is
assumed that the muscle is not receiving as many benefits as it could. This results in a less-
effective workout regimen.
Conclusion
It was concluded that there is a negative effect of performing cardiovascular exercise prior to
resistance exercise. In order for an individual to maximize the muscular gains that come from
resistance exercise, it is recommended that they perform resistance exercise prior to
cardiovascular exercise. It is important to also consider allow for a substantial buffer period
between exercises in order to allow for the constructive blood flow response to run its course
and provide the maximal amount of benefit to the exercised muscle.
References
1) Johnson, J.M., and Rowell, L.B. Forearm and skin vascular responses to prolonged
exercise in man. J. Appl. Phisiol. 39: 920-924, 1975
2) Rowell, L.B., Murray, J.A., Brengelmann, G.L., and Kraning, K.K. 2nd. Human
cardiovascular adjustments to rapid changes in skin temperature during exercise.
Circ. Res. 24: 711-724, 1969
3) Clifford, P.S., and y. Hellsten. Vasodillatory mechanisms in contracting skeletal
muscle. J. Appl. Physiol. 97: 393-403, 2004
37
4) Joyner, Michael J. Skeletal and Cardiac Muscle Blood Flow. Exercise and sport
sciences reviews. 33: 1-2, 2005
5) Coyle, E.F., and Gonzalez-Alonso, J. Cardiovascular drift during prolonged exercise:
new perspectives. Exercise and sport science reviews. 29: 88-92, 2001
6) Powers, Scott K., and Edward T. Howley. Exercise Physiology: Theory and
Application to Fitness and Performance. 3rd ed. Boston: McGraw-Hill, 2007. Print.
7) Carlson, Francis D., and Douglas R. Wilkie. Muscle Physiology. Englewood Cliffs,
N.J.: Prentice-Hall, 1974. Print.
8) George A Brooks and Thomas D. Fahey Exercise Physiology: Human Bioenergetics
and its Applicants. Ch.16 pg.337. 1984.
9) Dimitris Athanasopoulos, Zafeiris Louvaris, Evgenia Cherouveim, Vasilis
Andrianopoulos, Charis Roussos, Spyros Zakynthinos, Ioannis Vogiatzis. Expiratory
muscle loading increases intercostal muscle blood flow during leg exercise in healthy
humans. J. Appl. Physiol. 109, 388-395. 2010.
10) Christensen, E.H., Nielson, M., and Hannisdahl, B., Investigations of the circulation in
the skin at beginning of muscular work. Acta physiol. Scand. 4, 162-170. 1942.
11) Bishop J.M., Donald S., Taylor S.H., and Wormald P.N. The blood flow in the human
arm during supine leg exercise. J. Physiol. 137, 294-308. 1957
12) David M. Gundermann, Christopher S. Fry, Jared M. Dickinson, Dillon K. Walker, Kyle
L. Timmerman, Micah J. Drummond, Elena Volpi, Blake B. Rasmussen. Reactive
hyperemia is not responsible for stimulating muscle protein synthesis following
blood flow restriction exercise. J. Appl. Physiol. 112, 1520-1528. 2012
Appendix I – Informed consent
Consent for participation
Exercise Science Independent Study
The Effect of Cardiovascular Exercise on Reactive Hyperemia
This study is to be supervised by Cody Hatfield as part of a senior thesis requirement
handed down for the department of Kinesiology and Integrated Physiology at Hanover College.
38
It has the approval of the Hanover College Internal Review Board for the use of human subjects
in research.
8 male subjects will be studied. The ages of the subjects will range from 18-24. They are
all derived from an athletic background and have experience in handling free weights as well as
exercise machines. They are all physically fit and capable of participating in moderate physical
activity.
The purpose of this form is to disclose all procedures, as well as the risks or discomforts
that may be associated with your participation in the study. If at any point you become
uncomfortable, the study will be terminated. In fact, you may willingly cease involvement in the
study at any time, without reason or explanation. Full disclosure of the results of the study will
be available to you upon completion.
METHODS- Day 1
 You will arrive in room number 235 located on the second floor of the Science Center at
Hanover College.
 You will be required to wear either a sleeveless shirt, or asked to remove your shirt for
the measurement procedure.
 A baseline arm volume at rest will be taken via room temperature water displacement.
You will submerge your full dominant arm (up to a point of reference located just below
the armpit) into the water within the measurement apparatus and your arm volume will
be measured.
 You will then be asked to complete a set of bicep curls with your dominant arm using a
25-pound dumbbell weight. 20 repetitions will be completed. If the weight is too heavy,
a lighter weight will be provided.
 10-20 seconds after the set is completed, you will again submerge your dominant arm
for another measurement.
 Once you dry off, you are free to go for the first day.
METHODS- Day 2
The above procedures will be replicated with the following exceptions:
 After the baseline measurement is taken, you will be fitted with a Polar heart rate
monitor and asked to undergo moderate cardiovascular exercise on a stationary
treadmill. You will exercise at an intensity corresponding to a heart rate of 130 beats per
39
minute. The exercise will last for 30 minutes. You will be asked to wear the athletic
attire and sweat shirt for this portion.
 Once the exercise is completed, you will be able to rest for a period of 1-2 minutes.
 After the rest period, you will measure the volume of your dominant arm via the
submersion in the measurement apparatus.
 Then you will be asked to perform the same set of bicep curls with your dominant arm
once more. This consists of 20 repetitions with a 25-pound dumbbell. Again, if the
weight is too heavy, a lighter weight will be provided.
 Your dominant arm will be measured once more 10-15 seconds after the set of curls is
completed, and then you can dry off once that is finished.
RISKS AND DISCLAIMERS
All risks involved with this study are minimal, as both the cardiovascular exercise and
resistance exercise is moderate in intensity. However, as with any exercise, there is the
possibility of muscle soreness, fatigue, cramping, lightheadedness, or injury due to unforeseen
circumstances. These risks will attempt to be limited by the recruitment of conditioned athletes
to participate in the study.
You are encouraged to inform the researcher of any pain or discomfort being
experienced while participating in the study, in which case the study will be terminated
immediately.
Please note, if an injury should occur, there is no monetary compensation plan for
injuries related to the study. Therefore, all medical costs in the event of an injury will be your
responsibility.
Any questions, comments, or concerns can be directed to either Cody Hatfield (513-515-
1203 ; Hatfieldc16@hanover.edu), Dr. Bryant Stamford (Stamfordb@hanover.edu) , or Dr. Dean
Jacks (Jacks@hanover.edu).
AGREEMENT
By signing the form below, you are in compliance with the following:
40
1) You are willing to participate in the aforementioned procedure, regardless of the risks
mentioned, and with no pressure to participate.
2) You are, to the full extent of your knowledge, healthy and able to participate in all of the
above procedures to the best of your abilities.
3) You are participating without compensation for your participation.
4) You are aware that the data collected is for the use of Cody Hatfield as a part of the
fulfillment of the senior thesis requirement handed down by the Hanover College
department of Kinesiology and Integrated Physiology.
5) Your results may be subject to scientific publishing.
___________________________ _________
Name of subject (Please print) Date
___________________________ _________
Signature of subject Date
___________________________ _________
Signature of Cody Hatfield Date
___________________________ _________
Signature of Dean Jacks Date

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ST final write up

  • 1. 1 Table of Contents Abstract ……….……………………………………………………………….…….. 3 Chapter One ……………………………………………………………………..…. 4 Introduction…………………………………………………………………………………. 4 Statement of Purpose…………………………………………..………………………… 4 Significance of Study………………………………………..………………………………….. 5 Professional Significance………………………………………………..………..………….. 5 Personal Significance……………………………………….……………………………...…… 5 Delimitations…………….……………………………………………..…………………… 5 Limitations…….………………………………………………………..……………………. 6 Assumptions…………………..……………………………….…………………………..… 6 Hypotheses……………………………………………………………………………………… 7 Definition of Terms……………………………………………..……………………….. 7 Operational Definition of Terms………………………..…..……………………….. 8 Chapter Two………………………………………………………………………..……….. 9 Background Research……………………………………….……………………………. 9 Blood flow……………………..………………………………………………………….. 9 Blood flow through body …………………………………………………...… 9 Capillary exchange………………………..……………………………………….. 10 Blood flow redistribution during exercise…………………………………….…………….. 10 Reactive hyperemia……………………………………………………………………… 11 Thermoregulatory blood flow response…………………………………………………….. 11 Summary……………………….……………………………………………………12 Skeletal muscle physiology………………………………………………………….. 12 Muscle structure……………………………………………………………...… 12 Muscle contraction…………………………………………………….. 13 Muscle fiber type……………………………………………………………….…………….. 13 Summary…………………………………………………………………………..14 Muscle adaptations to exercise………………………………………………………..15 Neurological adaptations…………………………………………………………….15 Gene expression………………………………………………………………………….15 Hypertrophy……………………………………………………………………………..16 Fatigue/Fatigue resistance……………………………………………………………………16 Summary…………………………………………………………………………………….17 RelatedLiterature…………………………………………………………………………17 For hypothesis 1……………………..……………………………………………..….. 17 For hypothesis 2……………………………………………………………………………19 For hypothesis 3…………………………………………………………………………….19
  • 2. 2 Chapter Three ……………………………………………………………………..…. 20 Subject selection…………………………………………………………………..21 Researchdesign………………………………………………………………………21 Resistance exercise…………………………………………………………………21 Cardiovascular exercise…………………………………………………………………21 Instrumentation…………………………………………………………………………22 Pre-test Protocol………………………………………..………………………………….. 22 Test Protocol………………………………………………………..………..………….. 23 Procedure…………….……………………………………………..……………………… 24 Post-test protocol……………………………………………………………………….25 Calculations…………………………………………………………………………….25 Data treatment…………………………………………………………………….25 Pilot data timeline……………………………………………………………………..25 Chapter Four ……………………………………………………………………..…. 31 Data and results………………………………………………………………………….….. 31 Figure 1. Arm volume and CVE……………………………………………… 31 Figure 2. Arm volume and RE ………………………………………………………….. 32 Figure 3. Arm volume comparison………………………………………..………….. 32 Chapter Five………………………………………………………………………….33 Discussion………………………………………………………………………………….33 Conclusion…………………………………………………………………………………36 References……………………………………………………………………………….36 Appendix 1- Informed Consent Form………………………………………….37 Appendix 2- Institutional review Board Approval…………………………..41
  • 3. 3 The Effect of Cardiovascular Exercise on Reactive Hyperemia. Cody Hatfield Hanover College Department of Kinesiology and Integrated Physiology Sponsor: Dr. Bryant Stamford Abstract The purpose of this study was to investigate the impact of performing cardiovascular exercise prior to resistance exercise on reactive hyperemia in the dominant arm. Resistance exercise is known to “pump up” (reactive hyperemia) the exercised muscle. However, increased skin blood flow associated with cardiovascular exercise could reduce this effect. It was hypothesized that (1) arm volume will increase after each cardiovascular exercise or resistance exercise, and (2) the net arm volume increase when cardiovascular exercise is performed prior to resistance exercise will be lessened. This study was approved by the Hanover College Institutional Review Board with regard to the use of human subjects. Methods Eight fitness trained male subjects volunteered to participate. Arm volume was measured using a water displacement method, and measurements were taken after resistance exercise alone, after cardiovascular exercise alone, and after resistance exercise with prior cardiovascular exercise. The resistance exercise protocol consisted of a 20-repetition set of bicep curls using a 25-pound dumbbell weight, and the cardiovascular exercise protocol consisted of a 30-minute treadmill walk/run at a constant heart rate of 130 bpm. Results/Discussion Observations from several arm volume measurement comparisons revealed that muscular blood flow, as a result of resistance exercise, is restricted by increased skin blood flow due to a thermoregulatory response brought on by prior cardiovascular exercise. This finding accepted all hypothesis. The results suggest that performing cardiovascular exercise prior to resistance exercise provides a negative impact on the effectiveness of resistance training, so performing resistance exercise prior to cardiovascular exercise in the same workout is advised for achieving the best possible outcome of a workout.
  • 4. 4 The Effect of Cardiovascular Exercise on Reactive Hyperemia Chapter 1 Introduction When people go to the gym to work out, their workout plans usually contain some combination of cardiovascular exercise and resistance exercise. Many individuals have differing opinions on each exercise type, including pros and cons of both. It is widely accepted throughout the fitness community that a workout becomes the most effective when both exercises are performed at some point during the same workout. This brings up the question of which workout should be done first? It would make logical sense for an individual to begin their workout with the exercise that is least likely to negatively affect the remainder of their session. Research has shown that when performing cardiovascular exercise prior to resistance exercise, there is a conflict that arises regarding blood redistribution. Cardiovascular exercise elicits a thermoregulatory response that increases the amount of skin blood flow throughout the body in order to decrease the rising internal body temperature (1,5,10,11). Skin blood flow increase is temperature-dependent, meaning that the body will continue to profuse excess blood to the skin so long as the body temperature remains above homeostasis levels (1,5,10,11). Moreover, a decrease in body temperature is necessary in order to decrease the amount of skin blood flow. Sluggish blood redistribution occurs as a result (6,8). When resistance exercise is performed after cardiovascular exercise, the cardiac demand of the skeletal muscle increases (1,3,4,6,7,9). However, because the blood flow is still being redirected to the skin in order to siphon off metabolic heat produced from the cardiovascular exercise, there is less oxygenated blood available to be directed to the working muscle. This decrease in blood flow results in less reactive hyperemia within the active muscle (3,12). In theory, less reactive hyperemia in the muscle results in a less efficient resistance exercise workout. This study investigated the effects that cardiovascular exercise has on the blood flow redistribution to the working muscle during resistance exercise. Statement of Purpose To determine if prior cardiovascular exercise has a negative influence on reactive hyperemia in the dominant arm following exhaustive resistance training.
  • 5. 5 Significance of Study Professional Significance: Knowing the effects that cardiovascular exercise had on resistance training will help decipher the ultimate question of: “How should you organize your workout routine to maximize the benefits of both forms of exercise?” Of course, this will be specific to the workout goals of every individual, but the ability to determine a blood flow hindrance to the working muscle post- cardiovascular exercise could motivate the fitness community to model their workout plans to fit the workout that provides the best results. On a deeper level, this study can help examine the relationship between reactive hyperemia and resistance exercise. The ability to recognize a decrease in reactive hyperemia after resistance exercise with prior cardiovascular exercise has potential to show a negative impact in regards to muscle building. The working muscle needs a certain amount of oxygen and nutrients to fuel and repair itself after a lift. If that muscle does not receive all of those nutrients, then it is concluded that it is not being nourished in such a way that promotes maximal growth. In effect, cardiovascular exercise has a negative impact on resistance exercise. Personal Significance As an experienced weight lifter, I have often wondered if the workout I was performing was giving me the best results possible. A personal exercise goal of mine is to lose fat while putting on muscle. That would entail adding both aerobic exercise and weight training into my daily regimen. I am curious to know if by “warming up” with aerobic exercise, I am actually hindering my muscular gains by limiting the amount of blood flow to my working muscle. I am always looking for ways to improve my workout, and I believe this study will be a good first step in understanding how I should go about that. Delimitations This study was performed on 6 male subjects with a background in athletics. The independent variable was cardiovascular exercise, and the dependent variable was the amount of reactive hyperemia in the dominant bicep of the subject. To test each variable, each subject participated
  • 6. 6 in a control and an experimental trial. The control trial consisted of a simple arm volume measurement before and after a controlled set of bicep curls. The experimental trial had essentially the same structure, however, moderate-intensity cardiovascular exercise was performed prior to the set of bicep curls. The underlying question of this study was: Does performing cardiovascular exercise prior to resistance exercise result in a less efficient resistance workout? In order to answer this question, the blood flow competition that occurs when cardiovascular exercise is performed prior to resistance exercise was analyzed. The goal behind this method was to discover if a blood flow deficiency in the skeletal muscle occurred after resistance exercise with prior cardiovascular exercise. If arm volume increased after performing exercise, it was attributed to reactive hyperemia. Reactive hyperemia was then used as a measurement of workout efficiency. The more reactive hyperemia that occurred, the more efficient the workout was concluded to be. If a resistance workout was shown to produce less reactive hyperemia when cardiovascular exercise was performed prior to, then that combination of exercises was determined to be less efficient. Limitations  Small sample size of subjects limits the external validity  Only one experimental trial per subject  Only testing males, particularly athletic males  Only testing one specific form of cardiovascular exercise- running  Only testing one specific form on resistance exercises- bicep curls Assumptions  All subjects did not previously exercise prior to testing  Pipet cleaner apparatus was properly calibrated and yielded accurate measurements  All subjects are able to perform 20 repetitions of a bicep curl with a 25-pound dumbbell  Muscle volume increase is due to blood flow, and not any other external factors  Subjects did not eat a heavy meal before participation
  • 7. 7 Hypotheses It was hypothesized that arm volume will…. 1) Increase after resistance exercise alone 2) Increase after cardiovascular exercise alone 3) Increase less when cardiovascular exercise is performed prior to resistance exercise Definition of Terms 1) Reactive Hyperemia- An increase in skeletal muscle blood volume following a brief eclusion of the blood vessels due to muscular contraction. 2) Arteries- A vessel that carries Oxygenated blood from the heart to the rest of the body 3) Arterioles- Smaller diameter blood vessel that connects arteries to capillaries. Are extremely flexible as to accommodate for proper vasoconstriction/dilation needs. 4) Capillaries- Smallest blood vessel. Has porous membrane that allows oxygen and other nutrients to pass through into the cells. 5) Capillary Beds- End of the capillary where fluid exchange occurs. Oxygenated blood becomes deoxygenated blood at this time. 6) Capillary exchange- Hydrostatic pressure (blood pressure) causes fluid to exit the porous membrane of the capillary and supply nutrients to the surrounding cells. At the same time, Osmotic pressure (solute gradient) pulls fluid back into the capillary beds due to high solute concentration inside the capillary and high fluid concentration outside the capillary. Once the fluid re-enters the capillary, it is deoxygenated. 7) Diffusion- The random movement of molecules from an area of high concentration to low concentration 8) Pre-capillary Sphincters- Band of smooth muscle that adjusts blood flow into the capillaries. Can open/close depending on the amount of oxygen needed in the particular location 9) Venous return- Return of blood flow to the heart through the veins. Assisted by muscle pumps, pressure gradients, and gravity. 10) Venules- small blood vessels that carry blood from the capillaries to the veins 11) Vasomotor Tone – The amount of tension on the arterial walls that requires an artery to expand/contract. Affected by norepinephrine (constriction) and nitric oxide (dilation). 12) Norepinephrine- Released by adrenal gland and binds to alpha-receptors on blood vessels that causes constriction. 13) Nitric Oxide- Produced in the body. Binds to beta-receptors on blood vessels and causes vasodilation 14) Red Blood cell- Basic oxygenated blood cell. Carries oxygen and other nutrients all throughout the body through arteries.
  • 8. 8 15) Hemoglobin- Oxygen binding site in a red blood cell. This is how oxygen is able to be carried by the red blood cell. It is a protein consisting of 2 alpha and 2 beta dimers and includes four heme sites. 16) Cardiovascular Drift- The gradual, time-dependent change in several cardiac responses as a result of prolonged exercise. 17) Motor Unit- A motor neuron and all the muscle fibers innervated by that single motor neuron. Responds to an “all or none” manner to stimulus 18) Motor Unit Recruitment- The activation of additional motor units in order to accomplish an increase in strength of muscular contraction. 19) Fast-Twitch Fibers- Muscle fibers that have a high glycolytic capacity and a low oxidative capacity. Also referred to as “type 2 fibers” 20) Slow-Twitch Fibers- Muscle fibers that have a high oxidative capacity and a low glycolytic capacity. Have a slow contractile speed, but shows excellent endurance to repeated stimulus. 21) Thermogenesis- The the generation of heat as a result of metabolic reactions 22) Systolic Blood Pressure- The highest arterial pressure measured during a cardiac cycle 23) Diastolic Blood Pressure- Arterial blood pressure during diastole 24) Diastole- Period of filling the heart between contractions. Also known as the resting phase of the heart 25) Systole- Portion of the cardiac cycle in which the ventricles are contracting 26) SA node- Specialized tissue located in the right atrium of the heart. It generates the electrical impulse to initiate a heart beat. 27) Pulmonary Circuit- Refers to the portion of the cardiovascular system in which the blood travels from the right ventricle of the heart into the lungs and back to the left atrium. Blood becomes oxygenated at this stage. 28) Negative Feedback- Describes a response from a control system that reduces the size of the stimulus. Operationally Defined Terms 1) Water Displacement Apparatus- The tool used to measure arm volume via water displacement. It is filled with water, and the arm is submerged up to a stopping point. The measure of water increase in the tube can be simulated to suggest a change in volume.
  • 9. 9 Chapter 2 Background Research Blood Flow Blood flow through the body The purpose behind blood flow is to transport critical oxygen and nutrients throughout the body for the completion of many physiological processes necessary for life (6,7,8). To do this, blood needs to be forced through the blood vessels and delivered to the tissues. The heart acts as the pump that is the driving force behind blood circulation. The path that blood takes is described as follows (6): Blood begins in a deoxygenated form in the right atrium of the heart. From there, it is pumped through the tricuspid valve into the right ventricle during a phase known as diastole, or the refilling phase. Once the right ventricle is filled, it enters the systole phase, which is known as the contractile phase. This is the phase in which the ventricles contract and force blood to eject into one of two circuits. From the right ventricle, the blood then enters the pulmonary circuit. The main goal of the pulmonary circuit is to re-oxygenate the blood, and it accomplishes this through gas exchange that occurs in the alveoli. As the blood passes through the lungs, it acquires oxygen and releases carbon dioxide to be later expired. This newly oxygenated blood flows into the left atrium through the left pulmonary veins. The blood is then pumped through the bicuspid valve into the left ventricle, once again entering the diastole phase. Once filled, the left ventricle pumps the blood through the aortic valve and into the aorta to enter the systemic circuit during systole. Once into the aorta, blood then flows through several large arteries that branch out in all directions. As the arteries travel further from the heart, they eventually become near-microscopic. These microscopic blood vessels are known as arterioles. The arterioles are very flexible, and are suspect to various degrees of vasoconstriction and vasodilation in order to accommodate for multiple blood pressures and volumes, depending on the needs of the tissues in that area. Once through the arterioles, the blood flows through the pre-capillary sphincters and into the capillaries, the smallest form of blood vessel in the body. The capillaries are arranged into “beds” that perform capillary exchange, which is the method by which the oxygen and nutrients are extracted from the blood and delivered to the tissues. Once the oxygen and nutrients are delivered, the now-deoxygenated blood diffuses back into the capillaries. Blood flow back to the heart, or venous return, begins with the deoxygenated blood sitting in the capillaries. From the capillaries, the blood is transported into small venous vessels known as venules. Because venous return is not assisted, it calls for alternate mechanisms to help force blood back to the heart. Those mechanisms include: pressure gradients, muscle pumps, venous one-way valves, respiratory pumps, and gravity. Each of these mechanisms aid the blood to flow from the microscopic venules and into the larger veins. The veins use the
  • 10. 10 same venous return mechanisms to force blood up the inferior vena cava and back in to the right atrium of the heart, back where the blood first began the circuit (6). Capillary exchange The main role of the capillaries is to transfer oxygen and other usable nutrients to various body tissues. They perform this task through capillary exchange. The process begins with the oxygenated blood being pumped into the capillary through the pre-capillary sphincter, which opens when the tissue that it supplies is in need of more blood flow. Capillaries are comprised of single layer epithelial cells, which makes them highly permeable to oxygen molecules and other nutrients (6,8). These molecules then diffuse through the capillary wall with the assistance of hydrostatic pressure, or the pressure applied by the heart pump. and into the tissue, where they are metabolized. The waste fluid that did not contain nutrients is then diffused back into the capillary via osmotic pressure, or the pressure created from a concentration gradient. There is a low fluid concentration inside the capillary and a high fluid concentration outside the capillaries, which drives the osmotic pressure to push the fluid back into the capillary. This fluid is now the deoxygenated form of blood, which is pumped back to the heart via venous return mechanisms in order to be re-oxygenated (6,8). Blood flow redistribution during exercise In order to supply the working muscles with more oxygen and nutrients needed for exercise, it is necessary to increase the amount of blood flow that is being pumped to the working area. To do this, there needs to be several physiological changes that take place. Most notably, there needs to be an increase in cardiac output (6,8). The components of cardiac output are heart rate and stroke volume. Increasing heart rate will increase the rate at which newly oxygenated blood is pumped through the body, and increasing stroke volume will increase the amount of blood that is pumped to the body with each contraction of the left ventricle. However, increasing cardiac output only increases blood flow throughout the entire body, not to the specific muscle group that are working to perform the exercise. In order to channel the blood to a specific location, vasodilation of the blood vessels that supply the muscle occurs, as well as vasoconstriction of blood vessels that are supplying less-active portions of the body such as the liver and intestinal tract (1,3,6,8,9). Capillary sphincters also need to be opened during exercise to allow for the blood to be diffused into the capillaries. Vasomotor-tone occurs because the chemoreceptors in the working muscle will pick up an acidity change due to the production of excess carbon dioxide during metabolism. These chemoreceptors will then send messages to the cardiac control center of the brain, which will remove the sympathetic stimulation to the blood vessels supplying the muscle, causing them to vasodilate (1,3,6,8,9). The same signal will be sent to the blood vessels supplying the less-active tissues in order to increase the sympathetic innervation and cause them to vasoconstrict. This vasoconstriction of less-active tissues causes blood flow to be directed toward the most accepting blood vessels: the blood vessels supplying the working muscles. The increased amount of blood flow to the working muscle allows it to continue to produce energy for the purpose of completing the exercise.
  • 11. 11 The blood redistribution factor is rather impressive. Blood flow to the working muscle can increase from 15-20% during rest to 80-85% during exercise. At the same time, blood flow can decrease in a non-active organ such as the intestinal tract from 20-25% at rest to a mere 3- 5% during exercise (6). It displays the ability of the body to prioritize the physiological needs at any given time. Reactive hyperemia Reactive hyperemia is a phenomenon that that occurs when skeletal muscle blood flow overreacts due to the occlusion that occurs when a muscle contracts to 60% or more of its maximal capacity. To elaborate, the blood vessels that supply the working muscle are being squeezed and shut off by the force of the contracting muscle, thus incurring an inability to supply the muscle with oxygen and nutrients. During this time, the metabolic rate continues to increase, with continued insufficient blood flow. The body is receiving information that the muscle is not receiving enough blood, so it acts to make to blood vessels that feed it vasodilate maximally. These increases in blood vessel dilation are useless, however, until the muscular contractions cease. Once the contractions cease, an excessive amount of blood surges into the muscle, causing a hyperemia effect. This is the reasoning behind the “pump” that a weight lifter receives after a set of weight training (12). Thermoregulatory blood flow response. When the body undergoes extensive cardiovascular exercise, a thermoregulatory response occurs in reaction to the steadily increasing body temperature in order to keep the body at homeostasis (1,5,10). During exercise, the body is burning a lot of energy through metabolism. A side product of metabolism is heat. So, an increase in metabolism corresponds with an increased internal body temperature. To maintain homeostasis during exercise, the body works to eliminate as much excess heat as possible. From a blood flow perspective, the thermoregulatory response to an increasing body temperature is to increase the amount of skin blood flow (1,5,10). Increasing skin blood flow releases heat via convection. What this means is the blood will carry with it heat from the core of the body, which will be above 98.6˚F, and carry it to the skin, which is exposed to the surrounding environment. As long as the temperature of the surrounding environment is less than the temperature of the blood, heat will transfer from the hot blood to the cooler surrounding environment, causing heat to leave the body (6,8). The increase in skin blood flow occurs via much of the same processes that increase muscular blood flow during exercise. The blood vessels that supply the skin are ordered to vasodilate by the removal of sympathetic innervation to the vessels that was causing them to remain at a certain diameter. The vasodilation occurs in all of the skin blood vessels surrounding the entire body. Similarly, the blood vessels that supply less-active areas of the body are forced to vasodilate via increased sympathetic innervation (1,5,6,8,10). These areas would include the liver, intestinal tract, kidneys, etc. Blood flow to the skin is temperature dependent, meaning that the blood vessels that supply the skin will continue to be vasodilated until the internal body temperature drops back to homeostasis (1,5,6,8,10). This is thought to
  • 12. 12 contribute to sluggish blood redistribution to the rest of the body while the thermoregulatory response is occurring. Summary Blood flow as well as blood flow redistribution are extremely important physiological concepts that are pertinent to this study. Blood redistribution allows adequate blood flow to be available to a working muscle during exercise. The thermoregulatory response to exercise is to increase blood flow to the skin in order to expel heat from the body. Herein lies a blood flow conflict between the thermoregulatory systemand the active muscle. When the thermoregulatory response is activated, the increased skin blood flow causes poor blood redistribution due to the temperature-dependent nature of the vasodilatory mechanisms in the skin. The conflict occurs when the active muscle is not receiving an adequate amount of blood flow because of the excess blood profusion to the skin. This conflict could result in unsatisfactory results for the exercise; those unsatisfactory results amounting to a lesser amount of reactive hyperemia in the working muscle upon the ceasing of contractions. Skeletal Muscle Physiology Muscle structure Skeletal muscle is comprised of several different types of tissue. These include muscle fibers, nerve tissue, blood, and connective tissue (6,7,8). To begin, there are three different layers of connective tissue that surround a muscle. Those are (from outermost to innermost): the epimysium, perimysium, and endomysium. The epimysium wraps around the entirety of the muscle, binding the individual fiber bundles into larger. The perimysium surrounds the individual bundles of muscle fibers called fascicles. Within that lies the bundles of each individual muscle fiber. Those are surrounded by the endomysium. The arrangement of these bundles of fibers gives a muscle a striated appearance (6,7,8). There are two other types of muscle within the body that are quite different from skeletal muscle. Those are cardiac and smooth muscle. Cardiac muscle fibers are much shorter than that of skeletal muscle. Along with being shorter, the fibers of cardiac muscle are also more tightly compacted due to the fact that each fiber is not separated by an endomysium as it is in skeletal muscle. The lack of endomysium also accounts for the branched structure of the cardiac muscle fibers. The most important difference between the two muscle types is that cardiac muscle contains intercalated disks which transmit electrical impulses throughout the entire heart. This indicates that the entire heart can be stimulated using just one action potential. Skeletal muscle fibers are individually innervated, meaning that a different nerve impulse has to be present for each fiber of an entire muscle in order to allow for simultaneous contraction. This difference allows for the heart to contract automatically as compared to voluntarily. Smooth muscle is located within many organs and blood vessels, namely the arteries that carry oxygenated blood. Like cardiac muscle, smooth muscle is not striated, meaning that the individual muscle fibers are not wrapped in an endomysuim fascia. Also like cardiac muscle,
  • 13. 13 smooth muscle is able to contract automatically with a single nerve impulse. This allows them to provide a multitude of unassisted functions such as vasomotor tone, opening/closing of pre- capillary sphincters, and the swallowing of food as it moves down the trachea. The differences in muscle types allow for each type to possess a specific function, each just as important as the other. The intercellular aspect of a skeletal muscle cell contains many of the same components as a regular cell, except they are multinucleated, meaning they have multiple nuclei. Another unique component of a muscle cell is the myofibrils. Myofibrils are numerous threadlike structures that contain contractile proteins. The two main contractile proteins are called actin and myosin, with myosin being designated the “thick” filament and actin the “thin” filament. There are smaller proteins located within the actin filament called troponin and tropomyosin. Myofibrils are divided up even further into small segments known as sarcomeres separated by z-proteins. Myosin filaments are located on the A-band of the sarcomere and actin are located on the I-band. The small portion of sarcomere in which the a-band and I-band overlap is known as the H-zone. All of these small components of a muscle cell play critical roles in the contractile process (6,7,8). Muscle contraction Muscular contraction is a complex process involving several contractile proteins and energy production systems that results in the shortening of the myofibrils. A contraction begins with a nerve impulse from the motor neuron. This nerve impulse becomes an action potential that releases acetylcholine into the synaptic cleft of the neuromuscular junction. That acetylcholine then binds to receptors located on the motor end plate which causes a depolarization to occur inside the muscle fiber. When the depolarization reaches the sarcoplasmic reticulum, calciumis released. That calciumdiffuses into the muscle to eventually bind to troponin, which is the “trigger step” in the contractile process. When the calciumbinds to troponin, it causes the troponin to rotate around the actin filament, bringing with it tropomyosin, which exposes the actin binding site. Myosin, with attached ADP + Pi, then binds to the actin binding site. The ADP + Pi is then released, causing the myosin to bend, bringing with it the actin filament causing a shortening of the sarcomere. This act is called the power stroke, and it is the primary motion behind a muscular contraction. ATP will bind to the myosin head after the power stroke, causing it to detach fro the actin binding site. Once detached, ATP is broken down into ADP + Pi, causing the myosin head to extend once more. The process will repeat as long as calciumis present in the muscle fiber, leaving the actin binding site exposed for more power strokes. The simultaneous shortening of all the sarcomeres in a muscle cause the overall contraction, which is used to do move the body and do work (6,7,8). Muscle fiber type Muscles are categorized by differences in metabolism and contractile velocity (6,7,8). There are three different types of fibers in regard to these variables. Type 1 muscle fibers are known as slow twitch oxidative fibers. These muscles are primarily responsible for maintenance of body posture and skeletal support, but are also the main contributors in high-endurance
  • 14. 14 exercise. Type 1 fibers have a very slow contractile velocity, which makes them perfect for activities that involve long, slow contractions, such as distance running or cycling. Along with a slow contractile velocity, type 1 fibers also contain a very high concentration of oxidative enzymes which allow them to have a high capacity for aerobic metabolism. The ability of aerobic metabolism to produce a far greater amount of ATP than anaerobic metabolism (glycolysis) provides type 1 fibers with a very high resistance to fatigue (7). Type 1 muscle fibers, for this reason, are considered oxygen dependent. If oxygen is not constantly available to these muscle, then their ability to be fatigue-resistant wanes. The second type of muscle fiber, type 2 fibers, are further broken up into type 2a and type 2b fibers. Type 2a fibers are essentially opposite of type 1 in terms of contractile velocity and metabolism mechanisms. They are known as fast-twitch glycolytic fibers in that aspect. Type 2b fibers contract at a very high velocity, allowing them to produce significantly more force than their type 1 counterparts (7). On the same note, type 2b fibers do not have a very high capacity for aerobic metabolism, meaning that most of the ATP that type 2b fibers use comes from glycolysis, a much more inefficient metabolism mechanism. The results of this relatively low ATP production are that type 2b fibers cannot sustain their powerful contraction over a long period of time. This makes them useful for a lot of athletes who have to have quick, powerful reactions, such as a running back who has to cut sharply to avoid a defender, or a basketball player who has to jump to get a rebound. A benefit of type 2b fibers is that, because they do not have a very high capacity for aerobic metabolism, they are not as oxygen- dependent as type 1 fibers (7). This makes them more practical in conditions where oxygen is largely unavailable. Type 2a fibers are known as fast-twitch oxidative glycolytic fibers (6,7,8). These type 2 fibers are considered hybrids of both type 1 and type 2b fibers in that they carry characteristics relative to both. These fibers can rely on both aerobic (oxygen dependent) and anaerobic (non- oxygen dependent) metabolism mechanisms to produce contractions. This is why they are considered the “transition” or “intermediate” fibers between type 1 and 2b as a result of training (7). Type 2a fibers have the high contractile velocity and power of type 2b, so they are appropriate for activities similar to that of type 2b fibers. However, type 2a fibers can be trained to increase their oxidative capacity in order to become more fatigue-resistant. This ability makes them the most adaptable of the three fiber types. Summary Muscular structure and fiber type are crucial tokens of information to understand when discussing overall muscular performance. Because this study is centered around the performance of muscles during resistance training, it will be focusing mostly on type 1, slow twitch glycolytic muscles. Because slow twitch muscles are highly aerobic in nature, they are deemed oxygen-dependent. This means that slow-twitch muscles require a significantly greater amount of blood flow profusion than a type 2 fiber. If there were to be a lesser amount of blood flow post exercise (reactive hyperemia), then it could be concluded that the muscle was not receiving as much oxygen as it could have, meaning that it could have performed more
  • 15. 15 work if given more blood flow. This added amount of work could be considered added muscle contractions. However, if oxygen from the blood was not available, then the ATP is not being produced from aerobic metabolism. The ATP then could not perform its designated function in the contractile process, causing fatigue and eventual inability to contract. All of this information is suggesting that a lesser amount of blood flow will negatively affect the muscular performance during resistance exercise. Muscle Adaptations to Exercise Neurological adaptations A good portion of the strength gains that occur through training, especially those gained early on in the process, can be attributed to the ability of the body to recruit an increased amount of motor neurons to the working area (6,7,8). The increased number of motor units allows the muscle fiber to experience more action potentials, and thus more overall contractions. Having more motor units also allows for a greater strength of contraction initially. When more motor units are available for muscular innervation, there is a faster speed of contraction. A faster speed of contraction enables the muscle to contract with more force per contraction, thus increasing strength. Biochemical changes occur in muscle that influence increased physiological responses to exercise. Those changes would include: increase in feedback from chemoreceptors in the muscle and increased sympathetic nervous system innervation (6,8). Increased chemoreceptor feedback in the muscle allows for the muscle to respond to an increase in pH difference quicker. Because a pH difference would normally occur due to the increased production of carbon dioxide during the production of energy, a quicker response by the body would be to increase blood flow to the area faster. An increase in blood flow would result in more essential nutrients, as well as oxygen, being delivered faster, and this would decrease fatigue rate in the muscle. Increased sympathetic innervation would allow for the blood vessels surrounding the trained muscle to be more readily vasodilated, allowing for more muscle blood flow without having to assemble a response from the cardiac control center of the brain. Gene expression Genetics play a crucial role in the way individuals respond to resistance training stimulus. Every individual has a different genetic code derived from their DNA, which they acquire from their parents. Because genetic code differs in every human, the responses to resistance training differ from person to person as well. Gene expression is the activating of specific sections of the genetic code that allow for the synthesis of various proteins. Each individual has a multitude of different genes that either exacerbate or hinder the effects of training. Thus, when those genes are activated via training stimulus, different proteins are synthesized in order to both repair muscle tissue as well as cause it to grow, or hypertrophy. The degree to which these proteins are synthesized is different for all individuals (6,8).
  • 16. 16 Hypertrophy Resistance training consists of constantly overloading the muscles through the use of heavy weights. This overloading causes the muscles to increase in mass and cross-sectional area, a process known as hypertrophy (6,7,8). Satellite cells act to facilitate this muscle fiber growth. Satellite cells are located on the outermost layer of a muscle cell, in between the sarcolemma and basal lamina. These cells are activated when the muscle receives any form of trauma, such as the trauma associated with the resistance training overload. They fuse to damaged muscle cells and donate their nuclei, which aids in the regeneration of the cell as well as signals for more contractile proteins to be produced. This binding of satellite cells and influx of contractile proteins is the basis behind all muscle hypertrophy (6,7,8). The proteins that are produced are known as growth factors, and can be in the form of either hormones or cytokines. Three of the more important growth factors include insulin-like growth factor (IGF), fibroblast growth factor (FGF), and hepatocyte growth factor (HGF). IGF is secreted by the skeletal muscle and it regulates insulin metabolism, as well as stimulates protein synthesis. IGF and FGF both act to proliferate, or multiply satellite cells, causing an increase in the amount of satellite cells in the skeletal muscle. The more satellite cells that are present, the more they can influence hypertrophy (6,7,8). HGF is a cytokine with a slightly different function in the hypertrophy process. HGF helps activate the satellite cells and cause them to migrate to injured muscle cells. Hormones play an additional role in the hypertrophy of muscle cells. For example, growth hormone (GH) is a hormone produced by the pituitary gland that stimulates IGF within the skeletal muscle, adding to the satellite cell count, and overall hypertrophy (6,7,8). Similarly, testosterone is another hormone; more specifically, a male sex hormone. It has an amplified anabolic (muscle building) effect that is a major contributor to muscle hypertrophy, especially in men. Fatigue/Fatigue resistance Fatigue is defined as an inability to maintain a power output or force during repeated muscle contractions (6). From a neurological standpoint, fatigue sets in when a reduction of motor unit firing frequency occurs. From a physical standpoint, fatigue begins when the H+ concentration increases in the muscle. When a muscle is trained, it can increase its ability to resist fatigue from both the neurological and physical components. When a muscle is being heavily trained using resistance exercise, the first physiological adaptation that occurs is the increase of motor unit recruitment. An increase in the amount of motor units that are recruited during a contraction will lead to a higher motor unit firing frequency. This would result in a delay in the motor unit firing frequency decrease that causes fatigue, effectively increasing fatigue resistance. As resistance training continues over a long period of time, skeletal muscle hypertrophy begins to occur. Because the muscle type configuration in a resistance trainer is largely type 1, this means that a large portion of the trainer’s muscle has a high capacity for aerobic metabolism. Aerobic metabolism combines both H+ions and oxygen to produce ATP. The larger cross-sectional area that results from hypertrophy increases the mitochondrial density in the
  • 17. 17 muscle fiber, allowing for more aerobic metabolism sites to obtain the loose H+ ions and convert them into useable energy. When this happens, the concentration of free H+ ions in the muscle decreases exponentially, and fatigue takes longer to set in. Summary Muscular adaptations to resistance exercise are the prominent reasons for strength increase in weight lifters. Because strength gain is one of the more popular goals surrounding weight training, it can be used to determine the effectiveness of a particular workout. In respect to this study, it can help in determining if resistance exercise is hindered when less reactive hyperemia is present after the workout. While it may not have as much of an effect regarding the neurological adaptations, blood flow does have a distinct impact on the effectiveness of a muscle to build and increase strength. More blood flow would result in an increase in delivery of hormones such as GH and testosterone; both of which show anabolic effects in muscle. The muscle also needs to be able to repair itself after an overload. The essential oxygen and nutrients that are carried in the blood provide means for the muscle to repair itself, as well as to remove damaged muscle cells. Related Literature Hypothesis 1 Arm volume will increase after resistance exercise alone. Supportive Research 1) George A Brooks and Thomas D. Fahey Exercise Physiology: Human Bioenergetics and its Applicants. Ch.16 pg.337. 1984. 2) Dimitris Athanasopoulos, Zafeiris Louvaris, Evgenia Cherouveim, Vasilis Andrianopoulos, Charis Roussos, Spyros Zakynthinos, Ioannis Vogiatzis. Expiratory muscle loading increases intercostal muscle blood flow during leg exercise in healthy humans. J. Appl. Physiol. 109, 388-395. 2010. Because the first hypothesis was a universally accepted fact of resistance exercise, a good reference to start with was simply the exercise physiology textbook (item 1). Within chapter 16, it was mentioned that “During exercise there is a redistribution of blood from inactive to active tissues.” The textbook went on to describe the mechanisms behind blood redistribution to the working muscles, touching on important topics such as vasomotor tone and the sympathetic innervation that affects it. “There is a progressive increase in the amount of sympathetic vasomotor activity during exercise.” I believe all of the information learned about blood redistribution learned from this chapter in the textbook really supports hypothesis 1 by reinforcing the idea that blood gets funneled to the portion of the body that most
  • 18. 18 desperately needs it. In the case of my study, the bicep muscle is undergoing near-maximal resistance exercise. The intensity of this exercise is going to cause a large influx of blood after the muscular contractions have ceased (reactive hyperemia), causing the overall arm volume to increase as hypothesized. The second article by Athanasopoulos and colleagues (item#2) really encompassed the theme of blood redistribution to the working muscle. In an interesting study, the researchers attempted to investigate the effects of respiratory resistance on blood flow to the intercostal muscles during light exercise. The experiment they conducted involved a subject performing light exercise on a cycle ergometer during two trials: one with and one without respiratory resistance. Blood flow to both the quadriceps muscle and the intercostal muscles were measured via blood plethsmography. The principle discovery that was found from this study was that without respiratory resistance, blood flow initially increased in the quadriceps. However, once respiratory resistance was factored into the next trial, blood flow started to slowly decrease in the quadriceps and increase in the intercostal muscles. Because the same amount of exercise was being performed in each of the trials, the explanation could not come from the suggestion that the exercise became easier over time. The actual findings were based in the realm of blood redistribution. Blood is going to be redistributed to the area that most desperately needs it. More often than not, that area is going to be the muscle or muscle group that is performing the most work, thus needs the most oxygen and nutrients to perform that work. During the first trial of this study, where there was not respiratory resistance and the subject was only performing light cardiovascular exercise on a cycle ergometer, the only muscle group that was working was the quadriceps. Naturally, there was shown to be an increase in blood flow to the quadriceps during this time because that muscle group needed the blood the most. During the second trial, when respiratory resistance was introduced, there started to be a shift in blood flow redistribution from the quadriceps to the intercostal muscles. The reasoning behind this was because once the respiratory resistance was added, the intercostal muscles had to work extra hard in order to force air through the respiratory tract. So hard, in fact, that their work output overpowered that of the quadriceps, causing blood flow to redirect to the intercostal muscles. The ability of this study by Athanasopoulos and colleagues to relate comes from the proof that is displayed of blood redistribution to the hardest working muscle. It directly provides evidence that supports hypothesis 1 by reinforcing the blood redistribution factor that influences the volume of working muscles.
  • 19. 19 Hypothesis 2 Arm volume will increase after cardiovascular exercise only. Supporting literature 1) Christensen, E.H., Nielson, M., and Hannisdahl, B., Investigations of the circulation in the skin at beginning of muscular work. Acta physiol. Scand. 4, 162-170. 1942. The purpose behind the study was to investigate the participation of the skin as a vasoconstrictive mechanism of blood redistribution at the beginning of muscular work. The protocol consisted of the measurement of skin blood flow in the finger during light cardiovascular exercise using Burton’s plethysmographic method. One subject participated in this study and endured four trials of cardiovascular exercise at work outputs ranging from 360- 1260mkg/min. The study found that there was a distinct negative spike in skin blood flow within the first two minutes of exercise at all work outputs. This negative spike gradually increased over the course of the next 5 minutes, and surpassed that of the resting skin blood flow after ten minutes of exercise. This pattern was repeated during all four work outputs, showing remarkable consistency. As evidenced by the initial decrease in skin blood flow, it was shown that the skin does participate in the vasoconstrictive mechanisms of blood redistribution at the beginning of muscular work. However, the overall increase in skin blood flow that was observed over the entire course of the 22-minute exercise addressed another interesting point. The thermoregulatory systemdemands a relatively large amount of blood flow in order to release heat buildup from the metabolic processes that take place during cardiovascular exercise. This would require a shift in blood flow redistribution from the active muscles to the skin. The redistribution can be significant enough, as it was shown to be in the results of this study, to increase the skin blood flow to more than that of resting values. When skin blood flow is higher than resting values, there is more blood in the area than there normally would be during rest. That revelation leads to the accepting of hypothesis 2, that arm volume will increase after cardiovascular exercise alone. Hypothesis 3 Arm volume will increase less after resistance exercise when prior cardiovascular exercise is performed. Supporting literature 1) Johnson J.M., and Rowell L.B. Forearm skin and muscle vascular responses to prolonged leg exercise in man. J. Appl. Physiol. 39. 920-924. 1975. 2) Bishop J.M., Donald S., Taylor S.H., and Wormald P.N. The blood flow in the human arm during supine leg exercise. J. Physiol. 137, 294-308. 1957
  • 20. 20 The first study performed by Johnson and Rowell (item 1), had the purpose of investigating the muscular, as well as skin vascular responses to prolonged cardiovascular exercise in man. Their testing protocol involved 8 healthy adults performing 60 minutes of prolonged moderate intensity exercise on a cycle ergometer. Both their forearm muscle blood flow, as well as their forearm skin blood flow were measured throughout the entire 60 minutes. The results showed a progressive increase in overall forearm blood flow. However, there was revealed to be a slight decrease in muscular blood flow, meaning that the entire volume of blood flow increase originated from skin blood flow. This was due to the relative inactivity of the forearm muscle and the increased thermoregulatory response that occurred because of the excessive metabolic heat produced from the prolonged exercise. These results suggest that the cardiovascular exercise caused a very high response concerning skin blood flow presumably throughout the entire body, not just the forearm. Because this is the case, it supports hypothesis 3 that arm volume will increase less when cardiovascular exercise is performed prior to resistance exercise. It takes a significant amount of blood to profuse to the entirety of the skin because the skin covers every inch of the body. The readings that came from the forearm only are merely a fraction of the actual amount of skin blood flow occurring due to the thermoregulatory response of the exercise. The other 90% of the blood is trapped in the skin at other areas of the body, meaning that only a fraction of the overall blood volume is available to be redistributed to the muscle during resistance exercise post-cardiovascular exercise. This still shows arm volume increase, but not nearly to the degree that it would if that thermoregulatory response was not active. The second study performed by Bishop, Donald, and Wormald was very similar in methodology, except the second study performed the cardiovascular work while in the supine position. All of the same results were reached: increased amount of skin blood flow coupled with a slight decrease in muscle blood flow, attributing to a slight overall arm blood volume increase. The study merely suggested that position of the body relative to gravitational venous return showed no additional effect in blood redistribution. The body was able to overcompensate for this condition regardless of the natural tendency of the blood to move with gravity. This study continues to support hypothesis 3 by demonstrating the negative effect that skin blood flow during a thermoregulatory response has on overall blood flow redistribution. Chapter 3 The purpose of this study was to determine if prior cardiovascular exercise had a negative effect on reactive hyperemia in the dominant arm. An in-depth description of the subject selection, research design, instruments, procedures, and pilot data will be discussed in the following chapter.
  • 21. 21 Subject selection 6 male subjects participated in this study. They were all Hanover College students between the ages of 20-22. Each subject was determined to be physically fit; either participating or have had participated in Hanover College athletics. Physical fitness as well as experience in a weight room environment were taken into account when selecting subjects because it was important that the subjects be physically capable of completing the exercise procedures that were asked of them for the purposes of this study. Subjects were ultimately chosen vi willingness to participate. Research design The subjects were to participate in two trials: a control trial as well as an experimental trial. For the control trial, they were asked to gather a baseline arm volume, then perform the resistance exercise protocol and observe the change in arm volume after the resistance exercise. The experimental trial began with a similar protocol of that of the control protocol. The subject would first measure their baseline arm volume, then engage in the cardiovascular exercise protocol followed immediately by another arm volume measurement. The subject would then follow with a performance of the resistance exercise protocol once more followed by a final arm volume measurement. Overall net arm volume change from resting to post- resistance exercise was measured and compared in both protocols. Each trial was performed on subsequent days. Resistance exercise Each subject was asked to complete a resistance exercise protocol consisting of a 20- repetition bicep curl exercise using a 25-pound dumbbell weight. A smaller weight would be provided in the 20-repetition goal could not be met. This is important because repetitions are the key to this portion of the exercise. The subjects are supposed to be taking themselves to an exhaustive state, thus initiating the reactive hyperemia response. This response is not possible if only mild or moderate-intensity resistance exercise is performed. The subject was to only use their dominant arm. Cardiovascular exercise Each subject was asked to complete a cardiovascular exercise protocol consisting of 30 minutes of moderate-intensity exercise on a treadmill. The goal was to maintain a work output consistent with a target heart rate of 130 beats per minute for each subject. This goal would be specific for each subject, as they were each their own control with regard to fitness level and task specificity. This specificity was controlled by adjusting the speed and incline of the treadmill to accommodate the fitness levels of each subject. By using this method, it was possible to maintain a constant work output across the subject pool.
  • 22. 22 Instrumentation Arm volume measurement A modified water pipet apparatus was used to measure arm volume via water displacement. This equipment was self-calibrated and modified for this study alone. Resistance exercise (1) 25-pound dumbbell weight was used to administer the resistance exercise portion of the study. A smaller weight would be available if any subject would not complete the entire protocol with the 25-pound weight. Cardiovascular Exercise A Fitness T610 treadmill, Polar FS3 heart rate monitor, and stopwatch were required to administer the cardiovascular exercise portion of the study. Pre-Test protocol Control trial (a) Subjects were asked to wear appropriate clothing. Such clothing would include a sleeveless shirt, or possibly no shirt if preferable. The reasoning behind this would be because the subject would be completely immersing their arm in the water pipet filled with water. Having no sleeves would be for the benefit of accurate measurements and of the subject to not get their shirts wet. (b) Subjects were asked to not participate in any excessive physical activity at least 2 hours prior to participating in this trial. This is to ensure the accuracy and validity of the initial baseline measurements. Experimental (a) Subjects were asked to wear appropriate clothing. Such clothing would include a sleeveless shirt, or possibly no shirt if preferable. The reasoning behind this would be because the subject would be completely immersing their arm in the water pipet filled with water. Having no sleeves would be for the benefit of accurate measurements and of the subject to not get their shirts wet.
  • 23. 23 (b) Subjects were asked to being a sweatshirt with them to use during the cardiovascular exercise protocol. This was to in maximize the thermoregulatory response by the body in order to show maximal skin blood flow values (c) Subjects were asked to not participate in any excessive physical activity at least 2 hours prior to participating in this trial. This is to ensure the accuracy and validity of the initial baseline measurements Test Protocol Each trial consisted of several arm volume measurements using the modified water pipette apparatus. Every arm volume measurement was obtained using the following procedure: 1) The water pipette apparatus was filled with water all the way to the 230mm mark on the small measuring tape located at the top of the cylinder. 2) A few drops of blue food coloring were added to the water to ensure clear visibility during measurement. 3) The subject was marked with a dry-erase marker with a line just below the inferior portion of their dominant deltoid muscle. This would indicate how far the subject should insert their arm into the water pipette cylinder. 4) The subject would then insert their dominant arm all the way into the cylinder, stopping on the mark that was mentioned in the previous step. 5) Displacement of water was measured from before arm insertion to after arm insertion. All water levels started at 230mm. Water displacement was measured to the closest millimeter as designated by the white measuring tape adhered to the upper portion of the cylinder.
  • 24. 24 Procedures Control trial 1) The subject was asked to change into proper clothing, or to remove their shirt upon arrival in the physiology lab at Hanover College. 2) The subject rested for 15 minutes in a sitting position. 3) A resting arm volume was obtained using the water pipette apparatus 4) Dry off 5) The subject was then asked to complete the resistance exercise protocol as instructed 6) Arm volume was measured again 5 seconds after the completion of the resistance exercise protocol. 7) Dry off 8) Changes in arm volume were recorded and the subject was finished Experimental trial 1) The subject was asked to change into proper clothing, or to remove their shirt upon arrival in the physiology lab at Hanover College. 2) The subject rested for 15 minutes in a sitting position 3) A resting arm volume was obtained using the water pipette apparatus 4) Dry off 5) The subject then put on the sweatshirt that they were instructed to bring with them 6) The subject was then asked to complete the cardiovascular exercise protocol as instructed 7) Arm volume was measured again 5 seconds after completion of the cardiovascular exercise protocol. 8) Dry off 9) Changes in arm volume were recorded 10) The subject was asked to then proceed with the resistance exercise protocol once more 11) Arm volume was measured one final time 5 seconds after the completion of the resistance exercise protocol. 12) Dry off 13) Changes in arm volume were recorded and the subject was finished
  • 25. 25 Post-Test protocol Upon conclusion of each trial, the subject was encouraged to drink plenty of fluids as to rehydrate themselves after the participation in exercise. The subject was to report any feelings of nausea or fatigue to the instructor. All wastes were disposed of and the water pipette was properly drained according to the instruction manual. All supplies were stored and the lights in the lab were turned off. Calculations The water pipette apparatus was fitted with a small measuring tape that was adhered to the outside of the cylinder towards the top. This tape read millimeters of water displacement. Because the pipette was calibrated so that 1 centimeter of water increase was the equivalent of 200 milliliters of overall volume increase in the arm, the units had to be converted from millimeters to centimeters. Then that centimeter value could be multiplied by 200 in order to reveal the total amount of volume that was displaced. The following equation was used for this process: (initial volume (mm)) – (final volume (mm)) x 200 = Arm Volume (ml) 10 the final arm volume measurement was converted from milliliters to liters for data presentation purposes, as well as simplicity purposes. Data Treatment The data obtained in this study was organized by category into: Arm volume at rest, arm volume after resistance exercise alone, arm volume after cardiovascular exercise alone, and net increase. These values were statistically analyzed to calculate percent increases, averages, and overall volume change. Pilot Data Timeline Data session 1 The pilot data for this study began in modest fashion. The goal of the first session was to simply determine whether or not the measuring mechanism (the water pipette apparatus) was an accurate and reliable source of measurement data. To do this, there needed to be at least two arm volume measurements taken in succession of one another. Before this could take place, however, the optimal base volume of water in the pipette had to be determined. A trial and error process soon began in this calibration method. The overall volume of water in the pipette had to be set to a very specific level in order for the calibrations from previous uses to work. The first volume of water added was 8 liters, which proved to be an insufficient amount because the subject was unable to fully submerge the arm to the designated stopping point.
  • 26. 26 The water was dumped out and re-measured, this time to read 10 liters. This worked well for the needs of the study, as the subject was able to comfortably submerge their entre arm without causing the pipette cleaner to overflow. After this point, the decision was made to begin trials with the baseline volume of 10 liters. The protocol for this data was simple. The subject was asked to measure the volume of both their dominant and non-dominant arm for several trials, with one trial occurring each day. The goal was to stop the trials once two successive measurements for each arm were taken. If this occurred, the measurement method was considered reliable. If this did not occur within the framework of 5 trials, then the apparatus would have been deemed unreliable. Figure 1. Dominant and non-dominant arm volume measurement comparison. This pilot data was performed in order to prove the modified water pipette apparatus as an accurate and reliable piece of equipment. The dominant and non-dominant arms of the subject were measured twice over the period of two days. The goal was to record similar results for both trials. This would show consistency and reliability. As can be seen in the figures above, the dominant arm in both trials was larger than the non-dominant arm. The values possessed a relatively small spread as well, with the dominant arm ranging from 3.34L to 3.36L and the non- dominant arm ranging from 3.24 to 3.28. These values allowed the researcher to move on with their study with full confidence in the measurement equipment that was being used. Data session 2 3.34 3.24 3.2 3.22 3.24 3.26 3.28 3.3 3.32 3.34 3.36 3.38 Dominant Non-Dominant Volume(L) Trial 1 3.36 3.28 3.2 3.22 3.24 3.26 3.28 3.3 3.32 3.34 3.36 3.38 Dominant Non-Dominant Volume(L) Trial 2
  • 27. 27 The purpose behind gathering this data was to test hypothesis 2. It was hypothesized that arm volume will increase when resistance exercise is performed. This was an important session of pilot data because it provided solid parameters on which to base the control protocol that would be used for actual data collection later in the study. It also allowed for the measurement of reactive hyperemia in the bicep to be recorded and tested for . During this session, the subject was asked to measure their arm volume at rest to achieve a baseline measurement. After that they were asked to perform a set of 20 dumbbell curls with a 25- pound weight. The goal with these repetitions and weight was to maximally exhaust the subject, providing the muscle with the maximum amount of reactive hyperemia as possible. Figure 2. Arm volume at rest and after performing the resistance exercise protocol. These results display the change in arm volume from rest to after the performance of the resistance exercise protocol. The goal behind this data is to test hypothesis #1: arm volume will increase after resistance exercise alone. The hypothesis was accepted here, as there is a clear increase in arm volume from 3.68L at resting to 3.80L after resistance exercise. The increase was attributed to reactive hyperemia that occurred as a result of the near-maximal bicep curl exercise performed. Data session 3 3.68 3.8 3.62 3.64 3.66 3.68 3.7 3.72 3.74 3.76 3.78 3.8 3.82 Rest After RE Arm Volume after ResistanceExercise Volume (L)
  • 28. 28 This session was similar to that of the second data session in that change in arm volume was to be measured. Except in this pilot data, the second arm measurement was taken after cardiovascular exercise. This data allowed for the measurement of the thermoregulatory blood flow response that takes place after the performance of prolonged exercise. The subject was asked to gather another baseline measurement upon arrival. Then they participated in 30 minutes of moderate cardiovascular exercise on a treadmill with a work output of 130 bpm. The arm volume change was measured, and that change was attributed to the amount of increased skin blood flow to the arm as a result of a thermoregulatory response. Figure 3. Arm volume at rest and after performing the cardiovascular exercise protocol. These results display the changes that occurred in arm volume from rest to after the cardiovascular exercise protocol. The goal here was to test hypothesis #2: Arm volume will increase after cardiovascular exercise alone. The hypothesis was accepted here due to the clear increase in arm volume that is shown above in figure 3. There was an increase from 3.7L at resting to 7.76L after cardiovascular exercise. The increase was due to the increased amount of skin blood flow present due to the increased thermoregulatory response of the body. Data session 4 This data session was a bit trickier because this was s simulation of the entire experimental protocol. This required a lot of extra data collection. Data session 2 was repeated to determine the arm volume change due to resistance exercise only. To explain the experimental protocol, first the subject would acquire a baseline arm volume measurement. Then they would perform the cardiovascular exercise as explained in data session 3. Arm 3.7 3.76 3.62 3.64 3.66 3.68 3.7 3.72 3.74 3.76 3.78 3.8 3.82 Rest After CVE Volume (L)
  • 29. 29 volume change was then measured to incorporate the thermoregulatory response into the overall reactive hyperemia acquired at the end of the protocol. After all, skin blood flow affected overall arm volume, but was not included in the reactive hyperemia measurement. After the cardiovascular exercise protocol, the subject underwent the resistance exercise protocol. Arm volume was measured afterwards to determine the overall net change in volume that occurred over the entire process. That net arm volume change was determined to be the overall reactive hyperemia. This data session was intriguing because it shed light on the impact that the thermoregulatory response had on the overall amount of reactive hyperemia. The amount of arm volume increase after cardiovascular exercise was subtracted from the arm volume measurement at the end, leaving the difference to be the amount of reactive hyperemia present after the resistance exercise. Figure 4. (left) arm volume at rest and after resistance exercise alone. (right) arm volume measurements throughout entire procedure. Arm volumes taken at rest, after cardiovascular exercise alone, and after the following resistance exercise. This pilot data was used to test out hypothesis #3: Arm volume will increase less when cardiovascular exercise is performed prior to resistance exercise. The hypothesis was accepted, as there was less of an increase in arm volume during the experimental trial, where cardiovascular exercise was performed prior to resistance exercise, than in the control trial, where only resistance exercise was performed. The control trial displayed a net increase in arm volume of 0.07L while the experimental trial displayed a net increase of 0.04L. The middle bar on the experimental trial graph represents the change in arm volume from rest to after cardiovascular exercise alone. It is included to show the percentage of arm volume increase that is strictly skin blood volume increase. Data session 5 3.64 3.71 3.6 3.65 3.7 3.75 3.8 Rest After RE Control Trial Volume (L) 3.72 3.74 3.76 3.6 3.65 3.7 3.75 3.8 Rest After CVE After CVE + RE Experimental Trial Volume (L)
  • 30. 30 This data session was performed in order to answer a question that was brought up regarding the possible effect of water temperature on the vasodillatory mechanisms involved in reactive hyperemia. The preceding notion was that a colder water temperature might have a vasoconstrictive effect on the arm post-exercise, and that warm water may exacerbate the vasodillatory effects. In order to test this, additional arm volume measurements were taken at rest in water at 22˚C, 30˚C, and 40˚C. Those temperatures were used because of the temperature limits provided by the tap water in the physiology lab The goal was to test for any arm volume differences across the range of water temperatures. Any differences would indicate that an additional effect was being added by the water used to measure the arm. The results showed no volume changes in any of the temperature trials, indicating that water had no effect on the vasodilatory mechanisms in the arm. The conclusion was that the arm is only present in the water for a duration of approximately 15 seconds before being removed again. This is because it does not take long for the arm to be measured by the researcher, so to have the arm in the water for any additional time would be considered time wasted. Figure 5. Arm volume compared in three different water temperatures. This pilot data was used to answer the question of whether or not water temperature has any added effects on the vasodillatory mechanisms in the arm. The arm volume at rest was measured at temperatures of 22˚C, 30˚C, and 40˚C, presenting a wide range of temperatures to test. The arm volume remained constant at 3.68 liters throughout each trial. These results indicated no additional effect on arm volume provided by water temperature. 3.68 3.68 3.68 0 1 2 3 4 22℃ 30℃ 40℃ Volume (L) Volume (L)
  • 31. 31 Chapter 4 Data and Results Figure 1 displays an average arm volume increase of 0.04L when cardiovascular exercise was introduced to the subjects. This increase was calculated from an average resting value gathered from 8 different male subjects. The increase was deemed significant with a corresponding P value of <0.05 derived from a standard T-test. Hypothesis 1: Arm volume will increase after cardiovascular exercise alone – Accepted 3.42 3.46 3.4 3.45 3.5 Rest After CVE Arm Volume and CVE Volume (L) Figure 1. Arm volume change fromrestingvalues to after cardiovascular exercise was introduced. Data shown represents the average arm volume measurements of 8 subjects.
  • 32. 32 Figure 2. Arm volume change from resting values to after resistance exercise was introduced. Data shown represents the average arm volume measurements of 8 subjects. Figure 2 displays an average arm volume increase of 0.14L when resistance exercise was introduced to the subjects. This increase was calculated from an average resting value gathered form 8 different male subjects. The increase was deemed significant with a corresponding P value of <0.05 derived from a standard T-test. Hypothesis 2: Arm volume will increase after resistance exercise alone- Accepted Figure 3. Difference between overall net changes in arm volume. The left bar represents the net change in arm volume in each subject when strictlyresistance was performed. The right bar represents the overall net change in arm volume when both cardiovascular and resistance exercise were performed. The data shown represents the average arm volume measurements of 8 subjects. 3.37 3.51 3.3 3.35 3.4 3.45 3.5 3.55 Rest After RE Arm Volume and RE Volume (L) 0.15 0.13 0.05 0.1 0.15 RE CVE + RE Arm volume comparision between RE and RE= Net Volume Change (L)
  • 33. 33 Figure 3 displays a decrease in overall net arm volume change of 0.02L between when only resistance exercise was performed and when both resistance and cardiovascular exercise was performed. The change for resistance exercise alone was deemed significant with a corresponding P value of <0.05, while the change for resistance and cardiovascular exercise was deemed insignificant with a corresponding P value of >0.05. Both P values were derived from a standard T-test. Hypothesis 3: Arm volume will increase less after resistance exercise when prior cardiovascular exercise is performed- Accepted Chapter 5 Discussion Why does arm volume increase when cardiovascular exercise is performed? Increase in arm volume of any sort is described in this study as an increase in blood flow to the specified area, more specifically, the dominant arm of the subject. The increase in blood flow to the arm during this portion of the study can be attributed to the increased thermoregulatory response from the body as a result of the cardiovascular exercise (1,5,10). When the body undergoes cardiovascular exercise for any elongated period of time, it demands a high level of metabolic activity. The increase in metabolic activity creates a buildup of heat inside the body, causing the core temperature to increase to above homeostasis (1,5,10). The body is designed to maintain a constant core temperature in order to regulate several bodily processes correctly, so there are natural responses in place within the body that allow it to release any excess heat. The first of these responses is to increase the amount of blood flow to the skin. When blood is sent to the skin, it carries with it the excess heat from the core of the body. This extra heat is then released into the environment surrounding the body via convection where the hot blood releases the heat into the cooler surrounding environment, lowering the temperature of the body. This process will continue as long as there is metabolic heat buildup (6,8). The mechanism behind this blood redistribution to the skin is an elegant one. Once metabolic heat begins to build up, the blood vessels that supply the skin are ordered to vasodilate by the removal of sympathetic innervation to the vessels that was causing them to remain at a certain diameter. The vasodilation occurs in all of the skin blood vessels surrounding the entire body. Similarly, the blood vessels that supply less-active areas of the body are forced to vasodilate via increased sympathetic innervation (1,5,6,8,10). These areas would include the liver, intestinal tract, kidneys, etc. The vasodilation of the skin blood vessels along with the vasoconstriction of blood vessels in the lesser-utilized areas of the body combine to force blood into the skin and
  • 34. 34 remove heat. The increased amount of skin blood flow as a result of the thermoregulatory response of the body in what decidedly caused the increase in arm volume of the subjects during this phase of the study. Why does arm volume increase when resistance exercise is performed? Arm volume increase due to resistance exercise is directly attributed to the effects of reactive hyperemia that occur during such activity. The process of reactive hyperemia begins with a strong muscular contraction that is at least 60% of maximal capacity of the muscle in question. When the contraction is initiated, the blood vessels that supply the muscle become occluded by the muscle compressing against the skin. The occlusion denies the muscle of blood flow, causing it to starve for essential oxygen and other nutrients that it needs to continue to contract. However, the contractions continue and the muscle is consuming a lot of metabolic energy. The increase in metabolic output causes the body to vasodilate the blood vessels that feed the muscle in order to supply it with more blood flow to aid the desire for oxygen. Adversely, the blood vessels continue to be occluded by the muscle and it continues to be denied blood flow. This negative feedback loop of vasodilation as a result of metabolic demand from the muscle continues, causing a large amount of blood to be trapped in the vessel. Once the muscle relaxes, all the blood that had been previously detained by the blood vessel occlusion now rushes into the muscle, causing an exponential increase in the amount of blood in the muscle capillaries. This large increase in blood volume due to the hyperemic effect of resistance exercise is the direct cause of the overall increased arm volume of the subjects during this phase of the study (12). The mechanism behind muscular blood redistribution is relatively similar to that of skin blood redistribution. In order to channel the blood to the specific muscle, vasodilation of the blood vessels that supply the muscle occurs, as well as vasoconstriction of blood vessels that are supplying less-active portions of the body such as the liver and intestinal tract (1,3,6,8,9). Capillary sphincters also need to be opened during exercise to allow for the blood to be diffused into the capillaries. Vasomotor-tone occurs because the chemoreceptors in the working muscle will pick up an acidity change due to the production of excess carbon dioxide during metabolism. These chemoreceptors will then send messages to the cardiac control center of the brain, which will remove the sympathetic stimulation to the blood vessels supplying the muscle, causing them to vasodilate (1,3,6,8,9). The same signal will be sent to the blood vessels supplying the less-active tissues in order to increase the sympathetic innervation and cause them to vasoconstrict. This vasoconstriction of less-active tissues causes blood flow to be directed toward the most accepting blood vessels: the blood vessels supplying the working muscle. Why does arm volume increase less when cardiovascular exercise is performed prior to resistance exercise? The introduction of cardiovascular exercise prior to performing resistance exercise displayed a particularly interesting situation involving two separate, yet competing influences on blood
  • 35. 35 redistribution within the body. The two influences were that of thermoregulatory, as well as muscular blood redistribution. The competition ensues when the skin blood flow that occurs due to the thermoregulatory response of cardiovascular exercise deducts from the overall blood volume available to be redistributed to the working muscle during resistance exercise. This occurs because of the temperature-dependent nature of skin blood flow. To elaborate, the vasodilatory mechanisms that allow for increased skin blood flow in instances of high metabolic heat production will stay activated until the internal core temperature of the body decreases back to homeostasis (1,5,6,8,10). Because the exercise protocols were performed within minutes of each other, the body had not yet had time to release all the heat necessary to reduce the body temperature of the subject back to homeostasis. This caused the amount of skin blood flow to remain high, while simultaneously denying the working muscle (bicep) of the maximal amount of blood flow possible. These phenomena combined to display an overall lower average arm volume per subject when cardiovascular exercise was performed prior to resistance exercise as opposed to performing resistance exercise only. Skin blood flow shows sluggish redistribution due to several factors. The first of such factors is that skin blood flow occurs throughout the entirety of the skin, not just in the area that is being worked. During extensive cardiovascular exercise, the body works to maximize heat loss in any way it can. The best way for this to occur is to increase skin blood flow to as much of the external skin cells as it can. The more heat-carrying blood that is received by the skin, the more heat that can be lost through convection. Moreover, if the blood moves through the skin too quickly, it will retain some of the heat that could be lost. This is why blood tends to linger in the skin longer than usual; in order to release all the excess heat that it can before returning to the circulatory systemto cycle back through the process. This lingering effect can be described in the following figure: The left diagram displays the maximizing effect that results from the collective vasoconstriction of the skin blood vessels in correspondence with the lingering blood in the capillary beds of the skin. The end result of this action is the release of substantially more heat than is pictured in the right diagram, which displays the result of a lack of skin blood flow. Speaking in strictly thermoregulatory terms, the left diagram describes an extreme advantage in heat loss compared to the right diagram. In relevance to the study, however, it can be seen as a huge disadvantage. The lingering effect of the blood in the skin capillary beds significantly hinders
  • 36. 36 the ability of the body to recirculate that blood to be used for other purposes. Specifically, to be used as a constructive response to the overloaded muscle undergoing resistance exercise (1,5,6,8,10). In summary, there was a significantly less amount of blood flow available to the working muscle during resistance exercise when prior cardiovascular exercise was performed. This resulted in a less effective resistance exercise workout. Blood flow is the key to the effectiveness of resistance exercise. This is because the purpose of resistance exercise is to overload the muscle and cause it to make a positive change. This change is usually aimed towards hypertrophy, or increase in the size of the muscle. In response to this overload, the body provides a constructive response (blood flow) that is used by the muscle for repair and enhance itself. If that constructive response is limited by outside factors (thermoregulatory response), then it is assumed that the muscle is not receiving as many benefits as it could. This results in a less- effective workout regimen. Conclusion It was concluded that there is a negative effect of performing cardiovascular exercise prior to resistance exercise. In order for an individual to maximize the muscular gains that come from resistance exercise, it is recommended that they perform resistance exercise prior to cardiovascular exercise. It is important to also consider allow for a substantial buffer period between exercises in order to allow for the constructive blood flow response to run its course and provide the maximal amount of benefit to the exercised muscle. References 1) Johnson, J.M., and Rowell, L.B. Forearm and skin vascular responses to prolonged exercise in man. J. Appl. Phisiol. 39: 920-924, 1975 2) Rowell, L.B., Murray, J.A., Brengelmann, G.L., and Kraning, K.K. 2nd. Human cardiovascular adjustments to rapid changes in skin temperature during exercise. Circ. Res. 24: 711-724, 1969 3) Clifford, P.S., and y. Hellsten. Vasodillatory mechanisms in contracting skeletal muscle. J. Appl. Physiol. 97: 393-403, 2004
  • 37. 37 4) Joyner, Michael J. Skeletal and Cardiac Muscle Blood Flow. Exercise and sport sciences reviews. 33: 1-2, 2005 5) Coyle, E.F., and Gonzalez-Alonso, J. Cardiovascular drift during prolonged exercise: new perspectives. Exercise and sport science reviews. 29: 88-92, 2001 6) Powers, Scott K., and Edward T. Howley. Exercise Physiology: Theory and Application to Fitness and Performance. 3rd ed. Boston: McGraw-Hill, 2007. Print. 7) Carlson, Francis D., and Douglas R. Wilkie. Muscle Physiology. Englewood Cliffs, N.J.: Prentice-Hall, 1974. Print. 8) George A Brooks and Thomas D. Fahey Exercise Physiology: Human Bioenergetics and its Applicants. Ch.16 pg.337. 1984. 9) Dimitris Athanasopoulos, Zafeiris Louvaris, Evgenia Cherouveim, Vasilis Andrianopoulos, Charis Roussos, Spyros Zakynthinos, Ioannis Vogiatzis. Expiratory muscle loading increases intercostal muscle blood flow during leg exercise in healthy humans. J. Appl. Physiol. 109, 388-395. 2010. 10) Christensen, E.H., Nielson, M., and Hannisdahl, B., Investigations of the circulation in the skin at beginning of muscular work. Acta physiol. Scand. 4, 162-170. 1942. 11) Bishop J.M., Donald S., Taylor S.H., and Wormald P.N. The blood flow in the human arm during supine leg exercise. J. Physiol. 137, 294-308. 1957 12) David M. Gundermann, Christopher S. Fry, Jared M. Dickinson, Dillon K. Walker, Kyle L. Timmerman, Micah J. Drummond, Elena Volpi, Blake B. Rasmussen. Reactive hyperemia is not responsible for stimulating muscle protein synthesis following blood flow restriction exercise. J. Appl. Physiol. 112, 1520-1528. 2012 Appendix I – Informed consent Consent for participation Exercise Science Independent Study The Effect of Cardiovascular Exercise on Reactive Hyperemia This study is to be supervised by Cody Hatfield as part of a senior thesis requirement handed down for the department of Kinesiology and Integrated Physiology at Hanover College.
  • 38. 38 It has the approval of the Hanover College Internal Review Board for the use of human subjects in research. 8 male subjects will be studied. The ages of the subjects will range from 18-24. They are all derived from an athletic background and have experience in handling free weights as well as exercise machines. They are all physically fit and capable of participating in moderate physical activity. The purpose of this form is to disclose all procedures, as well as the risks or discomforts that may be associated with your participation in the study. If at any point you become uncomfortable, the study will be terminated. In fact, you may willingly cease involvement in the study at any time, without reason or explanation. Full disclosure of the results of the study will be available to you upon completion. METHODS- Day 1  You will arrive in room number 235 located on the second floor of the Science Center at Hanover College.  You will be required to wear either a sleeveless shirt, or asked to remove your shirt for the measurement procedure.  A baseline arm volume at rest will be taken via room temperature water displacement. You will submerge your full dominant arm (up to a point of reference located just below the armpit) into the water within the measurement apparatus and your arm volume will be measured.  You will then be asked to complete a set of bicep curls with your dominant arm using a 25-pound dumbbell weight. 20 repetitions will be completed. If the weight is too heavy, a lighter weight will be provided.  10-20 seconds after the set is completed, you will again submerge your dominant arm for another measurement.  Once you dry off, you are free to go for the first day. METHODS- Day 2 The above procedures will be replicated with the following exceptions:  After the baseline measurement is taken, you will be fitted with a Polar heart rate monitor and asked to undergo moderate cardiovascular exercise on a stationary treadmill. You will exercise at an intensity corresponding to a heart rate of 130 beats per
  • 39. 39 minute. The exercise will last for 30 minutes. You will be asked to wear the athletic attire and sweat shirt for this portion.  Once the exercise is completed, you will be able to rest for a period of 1-2 minutes.  After the rest period, you will measure the volume of your dominant arm via the submersion in the measurement apparatus.  Then you will be asked to perform the same set of bicep curls with your dominant arm once more. This consists of 20 repetitions with a 25-pound dumbbell. Again, if the weight is too heavy, a lighter weight will be provided.  Your dominant arm will be measured once more 10-15 seconds after the set of curls is completed, and then you can dry off once that is finished. RISKS AND DISCLAIMERS All risks involved with this study are minimal, as both the cardiovascular exercise and resistance exercise is moderate in intensity. However, as with any exercise, there is the possibility of muscle soreness, fatigue, cramping, lightheadedness, or injury due to unforeseen circumstances. These risks will attempt to be limited by the recruitment of conditioned athletes to participate in the study. You are encouraged to inform the researcher of any pain or discomfort being experienced while participating in the study, in which case the study will be terminated immediately. Please note, if an injury should occur, there is no monetary compensation plan for injuries related to the study. Therefore, all medical costs in the event of an injury will be your responsibility. Any questions, comments, or concerns can be directed to either Cody Hatfield (513-515- 1203 ; Hatfieldc16@hanover.edu), Dr. Bryant Stamford (Stamfordb@hanover.edu) , or Dr. Dean Jacks (Jacks@hanover.edu). AGREEMENT By signing the form below, you are in compliance with the following:
  • 40. 40 1) You are willing to participate in the aforementioned procedure, regardless of the risks mentioned, and with no pressure to participate. 2) You are, to the full extent of your knowledge, healthy and able to participate in all of the above procedures to the best of your abilities. 3) You are participating without compensation for your participation. 4) You are aware that the data collected is for the use of Cody Hatfield as a part of the fulfillment of the senior thesis requirement handed down by the Hanover College department of Kinesiology and Integrated Physiology. 5) Your results may be subject to scientific publishing. ___________________________ _________ Name of subject (Please print) Date ___________________________ _________ Signature of subject Date ___________________________ _________ Signature of Cody Hatfield Date ___________________________ _________ Signature of Dean Jacks Date