The document summarizes research on the pressor response, or blood pressure increase, during large muscle exercise like running versus small muscle exercise like knee extensions. It finds that the pressor response is greater during small muscle exercise due to less systemic vasodilation and a higher total peripheral resistance compared to large muscle exercise. This exaggerated response during small muscle exercise has implications for cardiovascular disease risk. Future work will analyze differences in pressor responses between age and fitness groups.
The Pressor Response Large Vs. Small Muscle Exercise
1. The Pressor
Response:
Large vs. Small
Muscle Exercise
Dustin Grinnell
Physiology Department
Pennsylvania State University
2. Background
The challenge of exercise
• During exercise, cardiovascular system must:
– Deliver adequate oxygen to working muscles
– Remove waste products (lactate, CO2)
– Regulate body temperature
– Maintain arterial pressure
• In other words, maintain homeostasis
3. Background
Arterial Blood Pressure
• Pressure: force exerted by
blood against arterial walls
• Systolic
– Pressure generated as blood
is ejected from the heart
during systole
• Diastolic
– Pressure during ventricular
relaxation
4. Background
Blood Pressure with Exercise
• 120/80 mmHg at rest
• 200/60 mmHg at max aerobic exercise
5. Introduction
• The Pressor Response
- This blood pressure response to exercise is called the
“pressor response”
Topic: Today I am going to talk about the blood
pressure response to two modes of dynamic exercise
and why we see a heightened response with small
muscle dynamic exercise.
6. Aim of the Study
• It was the aim of this study to:
1) Explore the blood pressure response to two
modes of dynamic exercise.
- The first exercise model used was the treadmill
running exercise, which employs the use of many
large muscles.
- The second exercise was a one-leg knee extension
exercise, which contracts only a few small muscles.
2) Understand if the pressor response was determined by
the active muscle mass.
7. Methods
Large vs. Small Muscle Exercise
VO2max Test Knee Extension Exercise
8. Methods
• The Proctor lab’s “fitness study”
-recruited 56 normotensive healthy men and women.
-Subjects fell into 6 groups based on age and fitness level.
-Young men, young women, low fit old men, high fit old men, low fit old
women, and high fit old women.
• All subjects performed:
- a large muscle exercise, a VO2max treadmill running test
- a small muscle exercise, a one-legged knee extensor exercise.
• Variables recorded:
-Heart rate
-systolic blood pressure
-diastolic -blood pressure
-mean arterial blood pressure was calculated post-
exercise.
9. Results
Pressor Response to Large Muscle Treadmill
Running
Systolic Blood Pressure Mean Arterial Blood Pressure
70 35
60 30
50 25
d S B P (m m H G )
d M A P (m m H g )
40 20
30 15
20 10
10 5
0 0
YM YW O M (LF ) O W (LF ) O M (H F ) O W (H F ) YM YW O M (L F ) O W (L F ) O M (H F ) O W (H F )
A g e G ro u p A g e G ro u p
dS B P dM AP
10. Results
Pressor Response to Small Muscle Knee
Extension
Systolic Blood Pressure Mean Arterial Blood Pressure
60 35
30
50
25
40
d S B P (m m H G )
d M A P (m m H g )
20
30
15
20
10
10
5
0 0
YM YW O M (L F ) O W (L F ) O M (H F ) O W (H F ) YM YW O M (L F ) O W (L F ) O M (H F ) O W (H F )
A g e G ro u p A g e G ro u p
dSBP dM AP
11. Results
Large Muscle Exercise vs. Small Muscle Exercise
Systolic Blood Pressure vs. MET
180
170
S B P (m m H g )
160
150
140
130
0 2 4 10 12 14 16
MET
T re a d m ill - S lo p e = 8 .0
K n e e K ic k - S lo p e = 2 6
More pronounced systolic blood pressure response during small muscle exercise
12. Results
Large Muscle Exercise vs. Small Muscle Exercise
Mean Arterial Blood Pressure vs. MET
125
120
115
M A P (m m H g )
110
105
100
95
90
85
0 2 4 10 12 14 16
MET
T re a d m ill - S lo p e = 4
K n e e K ic k - S lo p e = 1 6
More pronounced mean arterial blood pressure response during small muscle exercise
13. Results
• Pressor Response
• In response to both large muscle and small muscle exercise all
groups showed significant increases in:
-Systolic blood pressure
-Mean arterial blood pressure
• Mode-specific Response
• The blood pressure response was more pronounced during the
small muscle knee extension exercise compared to the large
muscle treadmill running exercise.
14. Summary
Why is the pressor response exaggerated in small muscle exercise
when compared to large?
• Treadmill Running
– An aerobic activity like running, involves the rhythmic and alternative
contraction and relaxation of many muscles which causes systemic
vasodilatation and a reduction in total peripheral resistance and a large
drop in blood pressure.
• Knee Extension
– During a knee kicking exercise, which involves the contraction and
relaxation of only a few small muscles only local, not systemic,
vasodilatation is seen, which results in little or no change to total
peripheral resistance and much higher pressor response.
15. Clinical Significance
• Why is an exaggerated blood pressure response a problem?
• Cardiovascular Risk
- The effects of an increased, or exaggerated pressor response to
exercise, in healthy people has important consequences in
cardiovascular disease such as coronary heart disease.
• Literature
- Many studies have looked at this exaggerated blood pressure response
to graded dynamic exercise in healthy people and have found it to be a
predictor of future hypertension and risk of cardiovascular mortality.
16. Clinical Significance
• Bond, et at.
– showed a higher pressor response to physical stress is found in
normotensives with a family history of hypertension.
• Stewart, et al.
– showed that the exaggerated blood pressure response is related to
impaired endothelial vasodilator function.
• Chang et al.
– showed that patients with exercise-induced hypertension have impaired
endothelium-dependent vasodilatation.
• Jae et al.
– showed that inflammation may be associated with an exaggerated blood
pressure to exercise.
17. Conclusions
• The pressor response during small muscle exercise,
during knee extension, exceeds the response seen in
exercise using many large muscles seen during
treadmill running.
• This exaggerated blood pressure response seen in
small muscle exercise has important cardiovascular
implications.
18. Future Directions
• Individual pressor responses may differ between the
fitness study’s 6 groups.
• Factors that can alter the blood pressure response to
exercise are:
• Age
• Sex
• Fitness levels.
• It is the aim of an upcoming paper, and the seminar talk
to present the data concerning these results.
19. Acknowledgements
Research Team
David Proctor, PhD (PI)
Joaquin Gonzales, PhD (Postdoc)
Sandy Smithmyer (Study Coordinator)
Julie Miedlar (Doctoral Candidate)
Collaborators
GCRC (University Park, Hershey)
Funding
Training Grants in Physiology, Seed Grant in
Gerontology Gerontology