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

• ↑ 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

• 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.