The next time your client complains that lactic-acid buildup is keeping her from doing her best, take it with a grain of salt. According to the August 20 issue of Science (2004; 305 [5687], 1112–13), lactic acid just may be “the latest performance-enhancing drug.”

This assessment was based on a study published in the same issue of Science (pp. 1144–47). The study found that lactic-acid accumulation, commonly thought to contribute to muscle fatigue, actually helps restore force to weakened muscles. “By altering the activity of chloride ion channels, lactic acid may actually boost the generation of action potentials and, hence, muscle activity even as the muscles begin to fatigue,” reported Science.

Look for more details on this topic in an upcoming IDEA Fitness Journal research column.