Pain and Soreness from Exercise: Is Lactate really to Blame?
Everyone has heard about Lactate and Lactic Acid. It has been said that this by-product is responsible for the process of acidosis (increase in acidity in the musculature), which inevitably leads to muscle soreness and the “burning” sensation after exercise. However, research in 2004 by Robergs et al. suggests that lactate has been in fact mis-labelled as the cause of acidosis. The answer lies in the chemistry. To keep it simple, during vigorous exercise there are two by-products produced, pyruvate and protons. Protons are essentially Hydrogen atoms (H+) which are acids. In order to neutralize the accumulation of acidity from these protons each pyruvate molecule absorbs two protons and turns it into lactate. Hence, lactate production actually retards the increasing acidity in the musculature and is NOT the cause of acidosis. It acts as a temporary neutralizer/buffer to the accumulation of protons during high intensity exercise.
So why do we still consider Lactate to be the cause of muscle soreness after exercise? Robergs and his colleagues (2004) explain that many textbooks do not explain the chemistry behind metabolic acidosis. This has led to the acceptance of misconceptions about lactate from many health professionals. So what of lactic acid? Where does that fit in? Robergs et al. (2004) identify that lactic acid is not produced in the body. Lactate has been considered the culprit for muscle pain and soreness in the past but is now off the hook.
So why does this matter? Since protons (aka acidity) can be buffered by the formation of lactate we can improve our buffering ability by incorporating endurance exercise into our training designs. This will help increase our threshold for muscular fatigue and help us when we do very intense resistance training. You can focus on increasing this threshold by performing lactate threshold training. Lactate threshold training involves doing endurance exercise that falls within your lactate threshold which is the exertion level just before your body cannot buffer the protons in your system. Typically this means exercising somewhere between 90-100% of your max heart rate. This will produce a physiological adaptation.
Note: having a heart rate monitor is highly recommended for this style of training.