To the Editor.
—Klesges and colleagues1 present data that appear to have profound implications for active individuals. Male basketball players lost bone mass during a 1-year period, and it was determined that this was mediated by loss of enormous amounts of calcium through sweat. The following year, with calcium supplementation, bone mass was gained. However, before athletes rush to consume calcium supplements, several important questions must be addressed.The first questions relate to collection and analysis of sweat samples. The authors state that they followed the procedure described by Tipton et al,2 but this does not appear to have occurred. Tipton et al2 used the arm-bag method to collect sweat, whereas Klesges et al1 extracted sweat from T-shirts worn under the athletes' regular jerseys. The authors do not establish that this method provides a valid estimate of sweat calcium concentration, and indeed it seems probable that
Barr SI, Heaney RP. Changes in Bone Mineral Density in Male Athletes. JAMA. 1997;277(1):22-23. doi:10.1001/jama.1997.03540250030024