Physiological Society

Lactate is continuously produced in skeletal muscle, even at rest, but with the onset of exercise, increases in the glycolytic resynthesis of ATP result in a correspondingly greater production of lactate in active fibres. Lactate metabolism is a dynamic process and while some fibres produce lactate, adjacent fibres simultaneously consume it as an energy source. [...]

Oxidative metabolism is relatively slow to adapt to the demands of exercise and the time constant of the response to heavy exercise is about 25 s. The rate at which ATP can be resynthesized is aerobically much slower than that of anaerobic ATP resynthesis but oxidative metabolism can use carbohydrates, free fatty acids (FFAs) and [...]