RELATIONSHIPS BETWEEN ENVIRONMENTAL TEMPERATURE (WBGT) AND BODY WEIGHT LOSS, FLUID INTAKE AND SWEAT LOSS DURING PHYSICAL EXERCISE / 体力科学

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=0.7NWB+0.2GT+0.1NDB, <BR>During baseball training, a commercially available sports drink was provided <I>ad libitum</I>, 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.<BR>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.