The terms lactic acid and lactate are often heard in gyms and on television. They are often wrongly associated with fatigue and muscle soreness that can be felt after a workout. This is actually a myth that seems to be well-established in the minds of people who work out, despite research showing that they are not responsible for cramps or pain. Here's the lowdown on lactic acid and lactate and their role in the body.
To produce energy, the human body uses adenosine triphosphate (ATP). This is a molecule that allows the energy present in the human body to be transformed into "work"; for example, to produce movement. Cells contain a small amount of ATP. In fact, the ATP stored in cells allows a rapid movement lasting a few seconds, such as jumping or sprinting, to be produced immediately . But the body always needs ATP, especially when energy demands increase during exercise. To overcome this problem, the body continually produces new ATP cells , this is called synthesis. Among these ATP-forming processes, there are those that are anaerobic, that is, those that do not require oxygen, and those that are aerobic, that is, those that require the presence of oxygen. Glycolysis, one of these ATP-producing processes, provides energy from the breakdown of glucose present in the muscles and can function without the presence of oxygen. This energy pathway acts predominantly during the first few minutes of exercise, particularly if it is very intense. Lactic acid is then produced. When intense exercise exceeds approximately 2 minutes, there is necessarily an accumulation of lactic acid. However, this quickly dissociates into hydrogen and lactate. Thus, the sensation of muscle fatigue or even burning would rather be caused by the presence of hydrogen, which causes muscle acidosis.
The acidity level that occurs after exercise takes about 10 minutes to return to a resting value.
However, only 2 to 3 minutes are enough to regain good performance capacity after high intensity exercise .
As for lactate, it is wrong to believe that it could be a waste product or even the cause of cramps or muscle fatigue . On the contrary, if it is not reused locally by the muscles that are directly solicited by an exercise, it will be transported and used as an energy substrate by the other muscles, the heart and the kidneys.
In conclusion, neither lactic acid nor lactate are responsible for exercise-related muscle soreness. In fact, short, intense workouts (10 seconds to 5 minutes) can have very beneficial effects by pushing back the threshold at which lactic acid accumulation occurs, thus reducing muscle acidosis caused by the presence of excessive hydrogen. This will result in better athletic performance.
