In this study, we investigated total sweat rate per unit area of body surface per hour (TSR), the percentage of total sweat loss to initial body weight (%TSL) and the percentage of fluid intake volume to total sweat loss (%FIV) in children (during baseball or basketball practice), young adults (during softball or baseball practice), and the elderly (during gateball practice) in summer. During the practice all participants were given access to drink sports drink or Japanese tea ad libitum. In the basketball group of children no sex difference was observed in TSR, %TSL and %FIV. Although TSR and %TSL in the baseball group of children were significantly higher than in the basketball group due to a higher WBGT, there was no group difference for %FIV. Children drank sports drinks (with carbohydrate-electrolyte) of the similar volume with total sweat loss. The baseball group of children showed a significantly greater %FIV compared to the young adult group regardless of simi lar %TSL, when they drank sports drinks. Children showed a significantly higher %FIV in sports drinks than in Japanese tea, whereas the %FIV of young adults was not affected by the type of beverage. The TSR, %TSL and %FIV of the elderly group were significantly lower than in young adults and children. These results suggest that children can prevent voluntary dehydration by con-suming sports drinks with carbohydrate-electrolyte ad libitum regardless of sex and WBGT, and that periodic drinking should be actively encouraged for the elderly because of their blunted rehydration ability, to prevent heat disorders during sports activity in summer.

Visceral fat accumulation is a notable risk factor in the incidence of lifestyle-related diseases such as metabolic and circulatory disorders. In this study, we measured visceral fat area (VFA) and subcutaneous fat area (SFA) in rugby football players by using dual bioelectrical impedance analysis, as well as other metabolic and circulatory parameters. A total of 28 male players (15 forwards, 13 backs; mean age±SD: 23±4 years) participated in this study. VFA and SFA were significantly correlated with body weight. Thus, heavier players had higher VFA and SFA as well as higher body weight. In addition, VFA was significantly correlated with various blood parameters such as alanine aminotransferase, gamma-glutamyl transpeptidase, and triglyceride. Six of the 28 players met the criteria for visceral obesity, defined as both body mass index ≥25 kg/m² and VFA ≥100 cm². In some of these players, blood parameters such as high-density lipoprotein cholesterol <40 mg/dL, triglyceride ≥150 mg/dL, or systolic blood pressure ≥130 mmHg indicated elevated risk for metabolic syndrome. These findings suggest that in athletes like heavier rugby football players, abdominal visceral fat accumulation may indicate risk of lifestyle-related diseases.