1. Physiological Adaptations
in Response to
Aerobic Training

2. Resting Heart Rate
 Trained athletes have a lower resting
heart rate due to increased efficiency
of the cardiovascular system and
higher stroke volume
 This is most evident in the recovery
phases
 The trained athlete can recover faster
(HR ’s faster) due to a more efficient
cardiovascular system.

3. Stroke Volume
 Amount of blood pumped out per beat
 Increases with aerobic training
 This occurs due to the heart becoming
stronger and the left ventricle fills
more completely during diastole
(resting phase of cardiac contraction)
More blood  more 02
=
 performance in aerobic activity

4. Cardiac Volume
 Cardiac Volume or Cardiac Output –
the amount of blood pumped per
minute
 Increases mainly due to Stroke
volume: CO = SV x HR
More blood  more 02
=
 performance in aerobic activity

5. Oxygen Uptake
 Oxygen Uptake (V02 max) is the best
indicator of cardiorespiratory
endurance because it indicates the
maximum amount of 02 that muscles
can absorb and utilise at that level of
work
 Training increases V02 max
 Lower in females due to less lean
muscles mass

6. Lung Capacity
 Lung capacity (amount of air that the
lungs can hold) is increased only at
the maximal exercise level
 Generally there is little change with
training
 Females have a lower lung capacity
due to smaller size

7. Haemoglobin Level
 Haemoglobin – substance in the blood
that bonds to 02
 Increases with training, particularly
with altitude training
More haemoglobin  more 02
=
 performance

8. Blood Pressure
 Blood pressure – measure of pressure
that blood exerts on the inner artery
walls
 Reduces with training, especially if
hypertensive prior to training

9. Muscle
Hypertrophy
 Muscle hypertrophy refers to muscle growth together with
an increase in the size of muscle cells, that is, bulking up.
 This occurs as a result of strength or resistance training
that stimulates activity in muscle fibres causing them to
grow.
 Hypertrophy does not occur as a result of aerobic training.
 Muscle fibres enlarge after training. Reasons for this
increase in size include the higher proportion of myofibrils
(the contractile element of the muscles). The fibres also
enlarge as a result of increased stores of glycogen and the
energy-supplying compounds (ATP and phosphocreatine -
PC) needed for the increased muscle size.

10. Effect on Fast/Slow Twitch
Fibres
 There are two types of muscle fibre:
 slow-twitch muscle fibres
 fast-twitch muscle fibres.
 Ratio of fast to slow-twitch fibres is thought to be
genetically determined.
 The metabolic capabilities of both types of fibres can
improve through specific strength and endurance
training.
 Sprinters and weight lifters have a large percentage of
fast-twitch fibres.
 Marathon runners generally have a higher percentage of
slow twitch fibres.

11. Effect on Fast/Slow Twitch
Fibres
 The adaptations that can occur in response to training
are shown in the table below.
Aerobic training - in slow- Anaerobic training - in fast-
twitch fibres twitch fibres
•hypertrophy of slow-twitch muscle •Increase and efficiency of ATP-
fibres PCsupply
•increased capillary supply to •increased glycolytic enzymes which
muscle fibres, improving gaseous improve functioning of the cell
exchange & movement of nutrients •hypertrophy of red-twitch muscle
and waste products fibres
•increased number and size of •increased tolerance of lactic acid,
mitochondria (energy factory of allowing performance to be
cells) enabling more efficient sustained for longer periods
energy production •muscle contractions can be made
•significant increase in myoglobin more forcefully and quickly as there
content (transports oxygen from are a greater volume of fast-twitch
the cell membrane to mitochondria) fibres

12. Remember:
Physiological Adaptations in Response
to Aerobic Training
Britney Blood pressure
Spears Stroke Volume
Obviously O2 Uptake
Lost Lung Capacity
Her Haemoglobin levels
Recording Resting HR
Contract Cardiac Output
Major Muscle Hypertrophy
Fail Fibres