Sauna-induced rapid weight loss decreases explosive power in women but not in men

This study aimed at investigating to what extent sauna-induced dehydration is effective to rapidly decrease body weight and whether this practice alters strength and/or explosive power (jump capacity) in healthy athletes. We also investigated whether the observed changes could be rapidly reversed through rehydration. Six male (aged 21.6 +/- 1.8 y) and six female (aged 24.5 +/- 3.7 y) athletes who were not familiar with weight cutting procedures were tested on three occasions: 1) before sauna, 2) after three consecutive sauna sessions (3 x 20 min at 70 degrees C, with 5 min rest interval), and 3) after one hour rehydration period (2.5 ml/kg body weight every 15 min). For rehydration, a carbohydrate beverage (6.3 % glucose, 9.5 mmol/l Na (+), 10 degrees C) was used. Evaluation consisted of body composition, strength (row-strength, handgrip-strength) and jump capacity (squat jump, counter-movement jump and elastic capacity). Sauna-induced dehydration, significantly decreased body weight in men (- 1.8 +/- 0.5 %) and women (-1.4 +/- 0.6 %). This reduction could not be rapidly reversed through rehydration. This weight cutting scheme did not affect strength or jump capacity in men. In women, a statistically significant decrease in squat jump was manifested after rehydration compared to pre-sauna values 23.7 +/- 2.2 vs. 25.2 +/- 1.4 cm, p < 0.05). The squat jump decrease in women was linearly and directly related to the percent reduction of body weight.