pe unit 4 aos 2 (chronic adaptations)

cardiovascular adaptations x8

• increased stroke volume of the heart

• decreased heart rate at rest and submaximal exercise

• increased capillarisation of the heart muscle

• increased capillarisation of the skeletal muscle

• faster recovery heart rates

• increased blood volume and haemoglobin levels

• increased cardiac output during maximal exercise

• decreased blood pressure

How does increased stroke volume of the heart improve aerobic performance?

Increased stroke volume is a result of the left ventricle enlarging which increases cardiac output. Thus more oxygen is delivered to muscles so more ATP is resynthesized aerobically. This allows the athlete to work at higher intensities for longer with fewer fatiguing factors.

stroke volume

amount of blood pumped out of left ventrocle per beat

How does decreased heart rate at rest and submaximal exercise improve aerobic performance?

Greater stroke volume means fewer beats required for same cardiac output. Slower HR increase during exercise, lower steady state achieved quicker → heart works more efficiently.

How does increased capillarisation of the skeletal muscle improve performance?

More capillaries in the skeletal muscles means there is greater blood flow & surface area for gas exchange. Increasing the oxygen and nutrients into the muscles for ATP aerobic production and allows for removal of by-products. This results in the athlete being able to work at higher intensities aerobically for longer, with fewer fatiguing factors

How does faster recovery heart rates improve performance?

Faster return to resting HR due to efficient cardiovascular system means there is quicker recovery between efforts and training sessions, allowing the athlete to work for longer periods without the onset of fatigue.

How does increased blood volume and haemoglobin levels increase perofrmance?

Aerobic training increases blood volume and haemoglobin levels, allowing more oxygen to be carried in the blood and delivered to working muscles. A higher plasma ratio also makes the blood less viscous (more thinner), so it flows more efficiently through vessels. Together, these adaptations improve oxygen transport and aerobic energy production, enabling the athlete to perform at higher intensities for longer with less fatigue.

cardiac output

the total amount of blood ejected by the left ventricle of the heart each minute.

• Q = HR × SV

How does increased cardiac output during maximal exercise improve performance

An increased maximal cardiac output means the heart can pump more blood per minute during intense exercise, mainly due to a higher stroke volume. This allows greater delivery of oxygen to the working muscles, enhancing aerobic ATP production and reducing reliance on anaerobic pathways.

How does decreased blood pressure improve perfromance?

Decreased blood pressure from improved vessel elasticity and reduced resistance allows blood to flow more efficiently. This reduces strain on the heart while enhancing oxygen delivery to the muscles. As a result, athletes can sustain aerobic exercise more effectively with reduced cardiovascular strain.

Respiratory adaptations to aerobic training

• increased tidal volume

• decreased resting and submaximal respiratory frequency

• increased pulmonary ventilation during maximal exercise

• increased pulmonary diffusion

• increased ventilatory efficiently

tidal volume

amount of air inspired and expired per breath.

How does increased tidal volume improve performance

An increased tidal volume means more air is inspired and expired per breath, allowing greater oxygen intake. This boosts oxygen diffusion into the blood and delivery to the muscles, resulting in greater ATP energy production.

How does decreased resting and submaximal respiratory rate improve performance?

With aerobic training, athletes breathe less often at rest and submaximal exercise because each breath is more efficient. This reduces energy spent on breathing and frees up more oxygen for the working muscles. As a result, the athlete can sustain aerobic activity more efficiently.

respiratory rate

breaths per minute

pulmonary ventilation

tidal volume x respiratory rate

How does increased pulmonary ventilation during maximal exercise improve performance?

During maximal workloads, ventilation increases due to greater tidal volume and breathing rate. This allows more oxygen to be delivered to the lungs and transported to the muscles, while more carbon dioxide is removed. Together, this supports higher aerobic energy production at maximum effort.

How does increased pulmonary diffusion improve performance?

Aerobic training results in a larger alveolar surface area, which improves the exchange of oxygen and carbon dioxide between the lungs and blood. This means more oxygen can be absorbed and more waste products removed. As a result, aerobic energy production becomes more efficient, delaying fatigue.

pulmonary diffusion

exchange of gases between aveoli and capillaries

ventilatory efficiency

efficiency of breathing muscles (e.g. intercostals, diaphragm)

How does increased ventilatory efficiency improve performance?

Improved efficiency of the respiratory muscles means they require less oxygen to function. This leaves more oxygen available for the working muscles, supporting sustained aerobic performance. The athlete can therefore maintain higher intensities with reduced fatigue.

muscular adaptations to aerobic training

• increased mitochondria and myoglobin

• increased aVO2 difference

• increased muscular fuel stores and oxidative enzymes

• increased oxidation of glucose triglycerides

• adaptation of muscle fibre type

How does increased mitochondria and myoglobin improve performance

Aerobic training increases the size and number of mitochondria (sites of aerobic ATP production) and the myoglobin within muscles (which transports oxygen to the mitochondria). This enhances the muscles’ ability to extract and use oxygen to produce energy aerobically. As a result, athletes can sustain higher intensities with less fatigue.

avO2 difference

How does increased aVO2 difference improve performance?

Trained aerobic athletes can extract more oxygen from their bloodstream into their muscles during both submaximal and maximal exercise. A greater a-VO2 difference enables more oxygen availability at the muscles for energy production.

How does increased muscular fuel stores and oxidative enzymes improve performance?

Aerobic training increases glycogen and triglyceride stores, as well as oxidative enzymes that break them down for energy. This provides more readily available fuel and delays reliance on anaerobic energy systems, reducing fatigue.

How does increased oxidation of glucose and triglycerides improve performance?

Muscles become better at oxidising glucose and triglycerides, which spares glycogen for later in exercise. This allows athletes to sustain higher intensities for longer before fatigue sets in.

How does adaptation of muscle fibre type improve performance?

Aerobic training makes fast-twitch fibres (especially type IIb) behave more like oxidative fibres, increasing their ability to use oxygen efficiently. This improves aerobic performance by allowing more muscle fibres to contribute to sustained energy production.

How does increased maximum oxygen uptake/VO2 max improve performance?

How does increased lactate inflection point (LIP) improve performance?