Lactic acid still remains the real cause of exercise-induced metabolic acidosis.

To the Editor: We appreciate the article of Robergs et al. (5), which gives a complete overview of the biochemistry of metabolic acidosis originating from intense muscular exercise. However, with the intention to clarify the causes of the pH decrease, the authors try to prove that lactic acid plays no role in this process and thus declare that generations of exercise physiologists have been using a false concept. We feel that this attempt results in confusion. A number of statements cannot be accepted: