Chronic adaptations to aerobic training - cardiovascular

Define cardiac hypertrophy

• Enlargement of the heart muscle, increasing left ventricle size and volume

Effect of increased left ventricle size

• Greater blood ejection from the heart, delivering more oxygen to working muscles

Increased stroke volume

• Stroke volume is higher at rest, submaximal, and maximal exercise due to cardiac hypertrophy, delivering more oxygen to muscles for sustained aerobic ATP production at higher intensities for longer with fewer fatiguing factors

Increased cardiac output

• Cardiac output rises at maximal exercise mainly from increased stroke volume, as heart rate changes little with aerobic training

Decreased resting and submaximal heart rate

• With higher stroke volume from training, the heart pumps more blood per beat, so fewer beats are needed at rest and submaximal exercise

Faster heart rate recovery

• Trained athletes’ hearts return to resting rate faster due to greater cardiovascular efficiency and aerobic energy production

Effect of aerobic training on blood pressure

• May lower blood pressure (especially among people who suffer from hypertension (high blood pressure)), reducing resistance to blood flow and heart strain, decreasing the risk of heart attack and other cardiovascular conditions

Effect of aerobic training on blood volume and haemoglobin

• Total blood volume may rise by up to 25% for an average adult male, red blood cells and haemoglobin content increase, enhancing oxygen delivery to muscles (oxygen carrying capacity of the blood may also rise)

How does increased blood plasma volume help

• Reduces blood viscosity, allowing smoother flow through vessels and better oxygen delivery to muscles

Effect of cardiac hypertrophy on heart muscle capillarisation

• Increases capillarisation, providing more blood and oxygen, allowing the heart to beat more strongly and efficiently during exercise and rest

Effect of aerobic training on skeletal muscle capillarisation

• Increases capillary supply to working muscles, improving blood flow, oxygen and nutrient delivery, removal of by-products, and contributes significantly to higher VO₂ max

Heart size and volume adaptation to aerobic training

• Increase

Capillarisation of heart muscle adaptation

• Increase

Capillarisation of skeletal muscle adaptation

• Increase

Total blood volume adaptation

Increase

• Red blood cells/haemoglobin: Increase

• Plasma volume: Increase

Stroke volume adaptation

• Rest: Increase

• Submaximal exercise: Increase

• Maximal exercise: Increase

Heart rate adaptation

• Rest: Decrease

• Submaximal exercise: Decrease

• Maximal exercise: No change

Recovery heart rate adaptation

• Faster

Cardiac output adaptation

• Rest: No change

• Submaximal exercise: Slight decrease

• Maximal exercise: Increase

Blood pressure adaptation

• Slight decrease

Increased left ventricle size and volume

• Cardiac hypertrophy increases left ventricle size and volume, raising stroke volume and cardiac output. More blood is ejected, delivering more oxygen for performance.

Increased capillarisation of the heart muscle

• Cardiac hypertrophy increases capillarisation, providing more blood and oxygen, allowing the heart to beat more strongly and efficiently at rest and during exercise.

Faster heart rate recovery

• Trained athletes’ hearts return to resting rates faster due to greater cardiovascular efficiency and aerobic energy production.

Increased blood volume and haemoglobin levels

• Red blood cells and haemoglobin increase oxygen-carrying capacity. Increased plasma volume reduces blood viscosity, improving smooth flow and oxygen delivery to muscles.

Increased capillarisation of skeletal muscle

• More capillaries increase blood flow, oxygen and nutrient delivery, and by-product removal, supporting higher VO₂ max and performance.

Decreased heart rate at rest and submaximal workloads

• Higher stroke volume means fewer heartbeats are needed to deliver required blood/oxygen. Heart rate rises more slowly during exercise and reaches steady state sooner.