Science of exhaustion?

[colarris]

I just wondered if somebody could briefly explain, very simplied, what is going in your body when you are exhausted? By that I mean you have worked hard for a few hours and feel like you need to sit down. What causes that condition? Is it lack or sugars?

[david23]

Your body is trying to make ATP using glucose. The fatigue you feel in your muscle comes muscle strain as well as lactic acid build up. Lactic acid is an intermediate of the glucose break down pathway. it's formed when you dont have enough oxygen to continue the break down process, so you are also out of breath

[colarris]

Thanks for the info

[jwalin]

to add to the info the lactic acid formed isn'twasted it will be rispired, changed to glucoe or lipids in the liver, which can be used further unlike the anaerobic respiration in unicellulars. the lactuc acid formed is due to the anaerobic pathway that the cells follow called the lactic acid pathway.

[MrMistery]

agreed with jwalin: lactic acid is not an intermediate, it is an alternative end product of a pathway that is used when there is no oxygen available. After you stop exercising, the lactic acid is taken to the liver, the liver runs the reactions in reverse to generate glucose, and then the glucose is taken back to the muscles so you can exercise again. This cycle of lactate/glucose between the liver and the muscles is called the Cori cycle, after the famous biochemists and Nobel Laureates Carl and Gerty Cori, who described the process.