Aerobic Power Notes

• Tidal volume


  The amount of air breathed in and out with each breath
• Acute responses of the respiratory system to exercise

  1. Increased respiratory rate from 15 at rest to 40 - 50

  2. Increased tidal volume from 0.5 litres at rest to 25 litres during exercise

  3. Increased ventilation (BRXTV) from 6 or 7 litres at rest to about 100 litres during exercise
• Only about 20% of CO₂ is carried by the haemoglobin - the rest is dissolved in the plasma or in the form of a bicarbonate ion
• Blood arriving back at the lungs has a high concentration of CO₂


  The alveoli have a low concentration of CO₂
• Minute ventilation = respiratory rate * tidal volume


  Therefore, CO₂ will diffuse from the capillaries into the alveoli
• Increased lung diffusion (alveoli to blood) is why CO₂ will diffuse from the capillaries into the alveoli
• Gaseous exchange


  Occurs because of differences in concentration and pressure levels
• Air breathed in and arriving at the alveoli has a high concentration of oxygen


  The capillaries surrounding the alveoli have blood with a low concentration of oxygen
• Oxygenated blood arriving at the muscle tissue


  The working muscle has a low concentration of oxygen
• Working muscles produce carbon dioxide (CO₂)


  The capillaries arriving at the muscle will have a low concentration of CO₂
• Aerobic power


  The maximal amount of oxygen taken in, transported and used by the body to produce energy per minute
• The higher your aerobic power, the more oxygen you can consume and the better your endurance and stamina
• Aerobic power is typically expressed in millilitres of oxygen per kilogram of body weight per minute (ml/kg/min) and is often used as a key measure of cardiovascular fitness and endurance
• Factors affecting aerobic power

  • Age
  • Gender
  • Training
• VO2 max declines with age

  After the age of 25, it decreases by 1% each year
• Exercise regularly to combat the effects of age on VO2 max