The Effect of Decreased Energy Intake under Hot Summer on Physique and Energy Expenditure in High School Baseball Players / 日本温泉気候物理医学会雑誌

ABSTRACT

Background & Objectives: Generally, food intake of athletes decrease under hot summer and, therefore, it would affect on their physiques and the athletic power (competition). The present study investigated the effect of decreased energy intake on athletes’ physique, energy expenditure and/or thyroid hormones. Methods: Forty two males of high school baseball team in Hokuriku area, Japan, participated in this study. The nutrition survey and physical measurements were performed, and total energy expenditure (TEE) from activity records were estimated in April, July, and December. Energy balance was determined from energy intake and TEE. Furthermore, the resting energy metabolism (REE) was measured by the expired gas analysis. Thyroid hormones were assayed respectively T3, FT3, and FT4. Results: Seventy percent of baseball players showed reduction of energy intake in summer. We, accurately, recognized that one can see two groups, i,e., a group that energy intake was decreased in summer (LA) and another was not decreased in the same summer (HA). Many subjects showed decrease of energy intake but their TEE was rather increased in summer. The energy balance of LA group was largely negative, but that of HA group was slightly negative. In LA group, body weight, BMI, and MAC (midarm circumference) were significantly decreased by 2∼4% in summer than that in spring, while the decrease of physical measurements is 1∼2% in HA group. Thus, a large negative energy balance affected the physique negatively. From energy composition of diet, it seems that LA group had high carbohydrate energy diet and HA group had high fat diet. There was a significant positive correlation between the energy intake and each of the nutrient intakes. The REE was significantly decreased in summer and thus it seems to be related with energy intake. FT3 and T3 were not changed in summer but were in winter, and it looks to be slightly related with REE. Conclusion: Decrease of energy intake in summer indicated a large negative effect on physique such as body weight, MAC. The decrease of energy intake in summer seems to be related with reduction of REE.