LB007 - COMPARISON OF HYDRATION STATUS AND WATER TURNOVER IN COLLEGIATE ATHLETES DURING SUMMER AND WINTER: A PILOT STUDY

LB007

COMPARISON OF HYDRATION STATUS AND WATER TURNOVER IN COLLEGIATE ATHLETES DURING SUMMER AND WINTER: A PILOT STUDY

E. Kondo^1,*, N. Takubo², A. Uchizawa^3,4, H. Hiraoka², H. Okada², H. Sagayama²

¹Department of Sport Sciences, Osaka University of Health and Sport Sciences, Osaka, ²Institute of Health and Sport Sciences, University of Tsukuba, Ibaraki, ³Department of Sports Sciences and Research, Japan Institute of Sports Sciences, ⁴Japan Society for the Promotion of Sciences, Tokyo, Japan

Rationale: Water is essential for athletic performance, and dehydration may cause symptoms such as fatigue, headache, and even heatstroke. Water turnover is affected by factors like fat-free mass, physical activity, age, and temperature. While athletes’ water requirements vary by season, few studies have compared hydration status between hot and cold environmental periods.

Methods:  Seven judo athletes (2 females; body weight: 72.7 ± 15.0 kg; body fat: 17.3 ± 4.0%) were included. After anthropometry and collection of blood and urine samples, total water turnover was measured using the stable isotope dilution method over one week. Measurements were conducted during both summer and winter, with ambient temperature recorded at 26.0 ± 1.9℃ and 16.5 ± 2.7℃, respectively.

Results: Water turnover was significantly higher in summer (5.9 ± 0.75 L) than in winter (4.1 ± 0.84 L, p < 0.05). Plasma osmolality remained within the normal range in both seasons but was slightly lower in summer (287 ± 2 mOsm/kg H₂O) than in winter (288 ± 1 mOsm/kg H₂O, p < 0.05). No significant differences were observed in plasma arginine vasopressin, total body water, urine specific gravity, or urine osmolality. Elevated levels of arginine vasopressin, exceeding 2.8 pg/mL, were observed in four participants in the summer and three in the winter. This finding suggests that approximately half of the participants may have experienced mild dehydration in both seasons.

Conclusion: In conclusion, water turnover was higher in the summer than in the winter, but approximately 50% of athletes showed signs of inadequate hydration in both seasons.

Disclosure of Interest: None declared