About lactate and exercise

Lactate has often been considered one of the major causes of both fatigue during exercise and post-exercise muscle soreness. However, lactate may have little effect on either. Moreover, it may help to improve performance.
Accumulation of lactic acid (generated form the anaerobic breakdown of glycogen), in the muscle, occurs only during short bouts of exercise of relatively high intensity and it is usually related to fatigue and muscle soreness. However, because lactate is so rapidly removed from muscle and blood after exercise, it is highly unlikely that lactate is the cause of any resulting muscle soreness. It may be that the accumulation of H+ ions during glycolisis contributes to fatigue during short-term intensive exercise. Oral lactate may postpone fatigue, by increasing buffer capacity of the body and reducing acidosis, in turn delaying fatigue.

On the other hand, it is believed that during endurance-type exercise, the depletion of muscle glycogen causes fatigue. In such conditions, lactate may serve as an energy source. It has been observed that the lactate produced in one muscle can be oxidized within another muscle. Due to its insulin independence, lactate could prove to be a more readily available energy substrate.

Better performance is often related to lactate clearance from the blood. The increase in blood lactate levels during exercise is reduced by acclimatization. Therefore training and lactate supplementation may help to increase lactate clearance and subsequently improve performance.