MUSCLE PHYSIOLOGY

Detailed explanation-1: -This burning sensation is associated with a buildup of acid in the muscles during intense exercise, and lactic acid has long been thought to be the culprit in that acid buildup, known as acidosis. Lactic acid is a byproduct of anaerobic metabolism, in which the body produces energy without using oxygen.

Detailed explanation-2: -When the body has plenty of oxygen, pyruvate is shuttled to an aerobic pathway to be further broken down for more energy. But when oxygen is limited, the body temporarily converts pyruvate into a substance called lactate, which allows glucose breakdown-and thus energy production-to continue.

Detailed explanation-3: -The concentration of blood lactate is usually 1-2 mmol/L at rest, but can rise to greater than 20 mmol/L during intense exertion. Blood lactate levels essentially serve as an indirect marker for biochemical events such as fatigue within exercising muscle.