Calcium losses resulting from an acute bout of moderate-intensity exercise

The purpose of this study was to compare daily calcium (Ca) losses in sweat (S) and urine (U) on an exercise day (E) with losses on the preceding day (i.e., a rest day) during which no exercise (NE) was performed. Ten healthy male volunteers (23.9 +/- 3.2 years) performed a single bout of moderate e xercise (running at 80% HRmax) for 45 min in a warm (32 degrees C, 58% rela tive humidity) environment on E. When E and NE were compared, neither Ca in take (1,232 +/- 714 and 1,148 +/- 482 mg, respectively) nor urinary Ca excr etion (206 +/- 128 and 189 +/- 130 mg, respectively) were different (p > .0 5). Sweat Ca losses during the exercise bout averaged 45 +/- 12 mg. The res ults indicate that, although a small amount of Ca is lost in sweat during 4 5 min of moderate-intensity exercise, measured (sweat and urine losses comb ined) Ca losses (251 +/- 128 and 189 +/- 130 mg) were not different (p > .0 5) between days (E and NE, respectively). These data suggest that moderate exercise for up to 45 min in a warm, humid environment does not markedly in crease Ca intake requirements.