Oxygen debt and the liver
Oxygen debt
During long periods of vigorous activity:
- lactate levels accumulate/build up
- glycogenAnimals store glucose as glycogen in their liver and muscle tissues. reserves in the muscles become low as more glucose is used for respiration, and additional glucose is transported from the liver.
This build-up of lactate produces an oxygen debtThe amount of extra oxygen required by the body for recovery after vigorous exercise..
As body stores of glycogen become low, the person suffers from muscle fatigue.
After exercise
The body's tolerance of lactate is limited so when a period of exercise is over, lactate acid must be removed.
Lactate is taken to the liver by the blood, and either:
- oxidised to carbon dioxide and water
- converted to pyruvate and glucose, then glycogen - glycogen levels in the liver and muscles can then be restored
These processes require oxygen. This is why, when the period of activity is over, a person鈥檚 breathing rate and heart rate do not return to normal straight away.
Taking in the amount of oxygen required to remove the lactate, and replace the body's reserves of oxygen, is called repaying oxygen debt.
When someone who has been exercising pays back an oxygen debt, it can take from a few hours for normal exercise, to several days after a marathon.