Chronic Adaptations to Endurance Training

VO2 max def + units measured in

• Maximum amount of O2 body can use per minute

• ml^-1/kg^-1/min (maybe add this to other flashcard set)

2 systems that adaptions occur to w/ brief description

• Central system: ability of cardiovascular + respiratory system to transport O2 + nutrients to, and remove waste from, active tissues

• Peripheral system: ability of working muscles to utilise O2 + nutrients to produce ATP

3 central adaptations

• Respiratory enhancements

• Increased cardiac output

• Increased blood volume + flow

2 respiratory enhancements that improve respiratory efficiency

• Increased tidal volume

• Improved pulmonary diffusion

Increased tidal volume explanation (2)

• Increased tidal volume → more air can move in and out with each breath → less ventilation required during sub-maximal exercise

Improved pulmonary ventilation 2 mechanisms

Gas exchange between alveoli and capillaries improves due to:

• Increased pulmonary blood flow and

• a denser network of micro-capillaries around the alveolar sacs

Structural changes to the heart (2) + what it leads to

• Increased size of left ventricle → more blood can be filled and pumped out

+

• Increased left ventricle wall thickness → contracts more forcibly

= Greater stroke volume

Typical increase in blood volume resulting from endurance training?

5.0-5.8L

What causes increased blood volume (initially + more slowly)?

• Plasma volume increases rapidly (within two weeks)

• RBC volume increases more slowly.

What improves blood flow? (3) w/ explanation

• Drop in hematocrit (% of RBCs) due to plasma volume increasing more rapidly → reduces viscosity + makes blood easier to pump

• Increased training stimulates growth of new capillaries (capillarisation) around muscle fibres, providing more surface area for the exchange of gases, nutrients, and waste

• More effective blood redistribution from inactive regions

3 peripheral adaptations

• Increased myoglobin content

• Mitochondrial biogenesis + increase in oxidative enzymes

How does increase myoglobin content improve ATP production efficiency? (1)

• Myoglobin (proteins found in muscle fibres) store O2 + release it to mitochondria → increased myoglobin → more O2 for mitochondria to use to produce ATP

Mitochondrial biogenesis def (1)

Increase in size + number of mitochondria in muscle cells

How does an increase in oxidative enzymes improve ATP production efficiency?

Conc. of enzymes that catalyse the breakdown of nutrients for ATP increases → higher rate of aerobic metabolism (pyruvic acid used for → ATP) and delaying the accumulation of lactic acid.

Lactate threshold def

The maximum intensity an individual can maintain without the excess accumulation of lactic acid in the blood

Lactate threshold in untrained vs trained individuals

• Untrained → threshold is smaller percentage of VO2 max

• Trained → higher percentage of VO2 max

Why is lactate threshold an important measure? (1)

• Indicates how long athletes can sustain higher intensity for → typically better indicator of endurance performance than VO2 max alone