The Theory of Lactic Acid

The production of Lactate (or lactic acid) occurs when we reach our aerobic threshold. In other words, this is the point in which we cannot consume enough oxygen to maintain our current level of exertion. Recent research shows that lactic acid is not bad, but rather helps the body get rid of acid . The story is actually quite complicated, but I will do my best to explain. Also click here..

During exercise, muscles produce acid in the form of H+ ions mainly due to the hydrolysis of ATP!! This is not lactatic acid!!!! To provide energy, muscles break down glucose to form pyruvate. Below the aerobic threshold, oxygen drives the degradation of pyruvate to form carbon dioxide (in the mitochondria). During this process, oxygen is reduced to water--which is most important for maintaining proper pH. The major point: This reaction consumes 2 H+ ions (in H2O) helping the muscles maintain a proper pH during aerobic exercise.

Above the aerobic threshold, more H+ is produced than can be used for oxygen reduction. Therefore, the pH in your muscles decreases (more acidic) and you begin to cramp. However, lactic acid comes to the rescue. Additionally, under these conditions, more pyruvate is produced than can be broken down into carbon dioxide (by mitochondria). So, there is too much H+ and too much pyruvate. Your body adds an H+ to pyruvate and produces lactatic acid and actually raises the pH (makes it more basic)!!! So, creation of lactic acid actually counterbalances the increase in acidity due to anaerobic exercise. Lactate then gets transported out of your muscles with an H+ (to balance the charge), further lowering the acidity.

Why doesn't the H+ just get transported out of the muscle directly? If this happened, your whole body would lower its pH as a result of your exercise and resulting in acidosis and most likely shock.