Transcript Adaptations to Exercise - CHOW

Adaptations to Exercise
Oxygen Delivery During Exercise
• Oxygen demand by muscles during exercise is
15-25x greater than at rest
• Increased delivery accomplished by:
• Cardiac output
• Redistribution of blood flow
(inactive organs  working skeletal
muscle)
Cardiac Output During Exercise
• Cardiac output increases due to:
– Increased HR
• Linear increase
– Increased SV
• Increase, then plateau at ~40% VO2max
• No plateau in highly trained people
Redistribution of Blood
during Exercise
• Increased blood flow to working skeletal
muscle
– At rest  15-20% of cardiac output to muscle
– Increases to 80-85% during maximal exercise
• Decreased blood flow to less active organs
– Liver, kidney, GI tract
• Redistribution depends on metabolic rate
– Exercise intensity
Circulatory Response to Exercise
• Changes in heart rate and blood pressure
• Depend on:
– Type, intensity and duration of exercise
– Environmental condition
– Emotional influence  raise pre-exercise heart
rate and blood pressure
Transition from Rest to Exercise,
Exercise to Recovery
• At onset of exercise:
– Rapid increase in HR, SV and cardiac output
– Plateau in submaximal (below lactate threshold in
exercise)
• During recovery:
– Decrease in HR, SV and cardiac ouput toward
resting
– Depends on:
• Duration & intensity of exercise
• Training state of subject
Cardiovascular Adaptations
to Aerobic Training
• ↑ muscular endurance
• ↑heart weight, volume, and chamber size
– Increased left ventricle wall thickness
– Increased left ventricle EDV
– Increased blood plasma
• ↑ Stroke Volume
– from ↑ EDV and ↓ ESV
• ↓ resting heart rate
• ↓ submaximal heart rate
• ↓ maximum heart rate of elite athletes
– if your heart rate is too fast the period of
ventricular filling is reduced  affects SV
– expends less energy by contracting less often
but more forcibly
• ↑cardiac output during maximal exercise
• ↑ blood flow to the muscles
– increased capillarization of trained muscles
– greater opening of existing capillaries in trained
muscles
– more effective blood redistribution
– increased blood volume
– decreased blood viscosity & increased oxygen
delivery
Terminology
• Tidal Volume = amount of air inhaled and
exhaled with each normal breath (500mL)
• Residual Volume = amount of gas remaining in
the lung at the end of a maximal exhalation
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Slight ↑ in Total lung Capacity
Slight ↓ in Residual Lung Volume
↑ Tidal Volume at maximal exercise levels
↑ respiratory rate and pulmonary ventilation
at maximal exercise levels
• ↑ VO2 Max
• ↓ VO2 at rest and submaximal exercise
• ↑pulmonary diffusion during
maximal exercise.
– from ↑ circulation and ↑ ventilation
– from more alveoli involved during
maximal exercise
Cardiorespiratory Adaptations
From Resistance Training
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Small ↑ in left ventricle size
↓resting heart rate
↓ submaximal heart rate
↓ resting blood pressure is greater than from
endurance training
• Resistance training has a positive effect on
aerobic endurance but aerobic endurance has
a negative effect on strength, speed and
power
– muscular strength is ↓
– reaction and movement times are ↓
– agility and neuromuscular coordination are ↓
– concentration and alertness are ↓
Long Term Benefits...
...To The Circulatory System
• Cardiac muscle hypertrophies (gets bigger)
– thicker, stronger walls = ↑ heart volumes = more blood pumped
around the body per minute, the faster oxygen is delivered to the
working muscles
• # red blood cells ↑ improving transport of oxygen for aerobic energy
production
• Density of the capillary beds ↑ as more branches develop 
efficient gaseous exchange
• Resting heart rate ↓(trained individuals) = efficient circulatory system
• Accumulation of lactic acid is much lower during high-levels activity,
due to circulatory system providing more oxygen and removing waste
products faster
• Arterial walls more elastic  greater tolerance of changes in BP
...To The Respiratory System
• Respiratory muscles (Diaphragm/intercostals)
increase in strength
• Larger respiratory volumes which allows more
oxygen to be diffused into the blood flow
(VO2 max)
• ↑ in the number and diameter of capillaries
surrounding the alveoli leads to ↑efficiency of
gaseous exchange.