Elite Athletes Hydration Profile And Renal Stress During Pan American (2019) And Olympic (2020) Games

Abstract

Elite athletes’ hypohydration may affect kidney function. Hydration profile can be assessed through Calculated Osmolarity (CO) [2x sodium + glucose + blood urea nitrogen] and urine specific gravity (USG) ≥ 1.020. PURPOSE: Our study aimed to observe the USG and CO profiles from Brazilian elite athletes during fasting in Lima Pan American (2019) and Tokyo Olympic (2020) Games and to verify if USG and CO could be used as indicators of renal stress. METHODS: Capillary blood and urine samples of 89 athletes from 13 sports were collected during fasting before the first participation of each athlete in both Games. Athletes were categorized according to sports characteristics: skill, power, endurance, and mixed. Hypohydration profiles were observed using USG and CO data from urine and capillary blood. Unpaired Student T-test and Welch`s correction were performed to compare CO from euhydrated and hypohydrated groups (USG ≤ 1.015; USG ≥ 1.020, respectively). Moreover, one-way ANOVA followed by Tukey's post-hoc was conducted to compare CO among sports. The effect size was calculated as Cohen´s d (T-test) and eta-squared (η2; ANOVA). Correlations were performed between creatinine and urea concentrations compared with CO (Pearson) and USG (Spearman). The significance statistic was established as p ≤ 0.05. RESULTS: Our data has shown differences for CO (p = 0.0006; d = 0.80) in euhydrated (287.3 ± 2.7; CI 95%: 286.6 - 288.0 mmol/L) and hypohydrated (289.9 ± 3.7; CI 95%: 288.6 - 291.2 mmol/L) group. No differences were observed among sports (p = 0.74; η2 = 0.01). According to renal stress biomarkers, results have suggested a weak correlation when USG and urea concentration were evaluated (r = 0.3; p = 0.0008) and no significant association was found in USG and creatinine concentration (r = 0.2; p = 0.086). Additionally, significant correlation was observed in creatinine (r = 0.2; p = 0.038) and urea (r = 0.3, p = 0.003) concentrations to CO data. CONCLUSION: Elite athletes are susceptible to decline in kidney function during Pan American and Olympic Games, independently of sports. Our data show a weak correlation between USG and CO and kidney function biomarkers. Therefore, these parameters should be carefully used to determine renal stress in elite athletes.