Effects of training intensity and environmental condition on the hydration status of elite football players

ABSTRACT Objective: To examine the effects of training intensity and environmental condition on the hydration status of Elite football players. Methods: Eleven elite football players completed three training sessions of varying intensity in cool (12°C) and warm (23°C) environments. Training demands was measured by Global Positioning System, sweat rate and sweat sodium concentration were measured using dermal patches and body mass change. Results: Warm condition increased sweat rate (0.9 ± 0.3 vs 1.7 ± 0.3 L.h-1, P<0.001), fluid intake (0.7 ± 0.1 vs 1.5 ± 0.2 L, P<0.001), total sodium loss (1405 ± 340 vs 2946 ± 958 mg, P<0.001) and total sweat loss (1.4 ± 0.5 vs 2.5 ± 0.4 L, P<0.001) compared to cool. Training intensity increased sweat sodium concentration (16.1 ± 6.6 vs 54.6 ± 22.2 mmol.L-1, P<0.001) and sodium loss (779 ± 231 vs 1405 ± 340 mg) in both environmental conditions. Total sweat loss and sodium loss were positively correlated with total distance covered (r=0.48, P=0.005 and r=0.4, P=0.023, respectively), meanwhile sodium loss was also positively correlated with the total number of high-intensity efforts (r=0.35, P=0.045). Conclusions: The results show that training load and environmental condition have a major impact on the hydration status of elite football players, hence hydration strategies should be developed accordingly.