While ventilation is driven by the need to expel carbon dioxide, the uptake of oxygen is a vitally important corollary effect
- Oxygen is required for aerobic respiration, by which large amounts of ATP are produced (relative to anaerobic respiration)
When describing oxygen intake, the following terms are commonly used:
- VO2 – The volume of oxygen absorbed by the body per minute and supplied to the tissues (i.e. oxygen consumption)
- VO2 max – The maximum rate at which oxygen can be absorbed and supplied to body tissues (i.e. maximum consumption)
At rest, the body does not consume the maximal amount of oxygen available to the tissues (oxygen deficit)
- As exercise intensity increases, the volume of oxygen supplied to the tissues also increases (up to the VO2 max)
- If energy demands exceed oxygen intake, ATP may be produced via anaerobic respiration (producing lactic acid)
- The lactic acid is transferred to the liver and requires oxygen to convert it back to a usable form (pyruvate)
- This extra oxygen required to restore normal body functioning after exercise is referred to as the oxygen debt
The body requires more oxygen to generate a set amount of energy when metabolising fats as compared to carbohydrates
- This is why there is an increase in carbohydrate metabolism and a decrease in fat metabolism with higher intensity exercise
Oxygen Uptake During Steady-State Exercise
