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

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 ↑ VO 2 Max ↓ VO 2 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 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.