METHODS: Forty-two soccer players (age: 27.34 ± 3.62 years; BMI: 23.80 ± 2.70 kg / m2; temperature: 30.8 ± 1.92 º C; humidity: 82 ± 1.4 %) hydration status were assessed using urine specific gravity (USG) and bodyweight (BW) as the objective measures, meanwhile, thirst was measured subjectively using a thirst scale. For performance evaluation, 20 and 50 m sprint time were measured before and after match.
RESULTS: The results showed a significant relationship between USG and sprint time (r = 1.00 (CI 0.98 - 0.99); p < 0.05), and as expected, USG at post-match was significantly higher than pre-match (p < 0.05) indicating dehydration. In line, changes (between post and pre-match) in BW also showed positive relationship with changes in sprint time (r = 0.99 (CI 0.98 - 0.99); p < 0.05). Not to our expectation, the self-reported thirst level was not found to be correlated with USG and sprint time.
CONCLUSIONS: Objective measures better reflect hydration status and predict sprint performance compared to subjective measure when playing in hot and humid environment. Players need to monitor their hydration status to maintain their sprint performances.