Muscular Exercise (during long vigorous exercise)

Starting Phase

Muscle cells respire aerobically
Increase in breathing rate (remove carbon dioxide and take in oxygen at a faster rate)

Exercising Phase

After a while, the amount of oxygen supplied during maximum aerobic respiration is not enough to meet the demand of energy needed by the contracting muscle cells.
Muscle cells respire anaerobically
Lactic acid is formed
Muscle cells incur oxygen debt
Lactic acid concentration build-up/accumulate in muscle cells until it reaches a point where concentrations are high enough to cause muscle fatigue, pain and discomfort
The body then needs to rest and recover.

Rest and Recovery Phase

Breathing rate continues to be high for a period
Provide sufficient oxygen to repay oxygen debt
Lactic acid is gradually removed from the muscles and transported to the liver
In the liver, lactic acid is oxidized to convert some lactic acid back to glucose.
Glucose transported back to muscles.

	Created by Davyd Tan over 10 years ago

Note on Respiration, created by Davyd Tan on 15/04/2014.