(WBGT) AND BODY WEIGHT LOSS, FLUID INTAKE AND SWEAT LOSS DURING PHYSICAL EXERCISE

Transcription

1 RELATIONSHIPS BETWEEN ENVIRONMENTAL TEMPERATURE (WBGT) AND BODY WEIGHT LOSS, FLUID INTAKE AND SWEAT LOSS DURING PHYSICAL EXERCISE SEIICHI NAKAI, TETSUYA YOSHIDA, AKIRA Y0RIM0T0, NAOKI OKAMOTO and TAKETOSHI M0RIM0T0 Abstract The relationship between environmental conditions and water balance during training for baseball and American football was analyzed. The environmental conditions were assessed in terms of WBGT (wet-bulb globe temperature) based on NDB (natural dry-bulb temperature), NWB (natural wet-bulb temperature) and GT (globe temperature), as WBGT=0.7 NWB+ 0.2 GT+0.1 NDB, During baseball training, a commercially available sports drink was provided ad libitum, whereas during American football training, the effect of free water intake was compared between tap-water and sports drink. The sweat rate and the amount of water consumption were significantly correlated with WBGT under each experimental condition. Body weight loss was 0.2% body wt./h during baseball training, whereas during American football training, body weight loss was 0.5%/h with tap-water and 0.4%/h with sports drink on average, revealing a significantly higher value for tap-water. These results indicate that both sweat loss and water intake during exercise increase with WBGT, and that body weight loss is maintained at a fairly constant level during exercise with free water intake, although the loss is significantly higher when tap-water is provided. (Jpn. J. Phys. Fitness Sports Med. 1994, 43 : ) key words : sports training, weight loss, drinking, sweat loss, WBGT Kyoto Women's University, Higashiyamaku Kyoto-shi, Kyoto 605, Japan Department Medicine, of Physiology, Kyoto Prefectural University of Kamigyoku Kyoto-Shi, Kyoto 602, Japan Kyoto Institute of Technology, Faculty of Engineering and Design, Matsugasaki Gosyo Kaidocho, Sakyoku, Kyoto-Shi, Kyoto, 606, Japan Shiga Prefectural Junior College, Hikone-Shi, Shiga 522, Japan Ritsumeikan University, Tojiin Kitamachi, Kitaku, Kyoto-Shi, Kyoto, 603, Japan

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3 Fig, 1, Environmental temperature (WBGT) and body weight loss, fluid intake and sweat loss during baseball training.

4 Fig. 2, Relationships between WBGT and sweat loss, fluid intake, and body weight loss during baseball training. ***=p<0.041 Fig. 3. F nvironmental temperature and sweat loss (fluid intake+weight loss) during football training with free access to tap water. Fig. 4. Environmental temperature and sweat loss (fluid intake+weight loss) during football training with free access to sports drink.

5 Fig, 5, Relationships between WBGT and sweat loss, fluid intake, and body weight loss and WBGT during football training (the upper figure with free access to sports drink and the lower figure with free access to tap water). *=p<0,05, ***=p<0.001

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