Effects of Water Consumption and Body Water Content on Exercise Performance in Recreational Athletes

Objective: To evaluate water consumption and body water content of recreational athletes to determine their effects on physical fitness and performance. Methods: This secondary cross-sectional investigation utilized data from Drexel University. Participants had their data collected over two visits to the laboratory. Measurements taken in the original study included: aerobic fitness assessed via maximal oxygen consumption (VO2max) using a metabolic cart, resting metabolic rate (RMR) evaluated using a metabolic cart, body composition measured by dual-energy X-ray absorptiometry (DXA), body water content measured by bioelectrical impedance analysis (BIA), kilocalories (kcals) from vigorous physical activity measured using Actical accelerometers, water consumption assessed by asking participants how much water they consumed the day prior to each visit (at both time points), and dietary data from the 2005 Block Food Frequency Questionnaire (FFQ). R studio (RStudio 2023.12.1 Build 402 "Ocean Storm" for Windows, 2024, Posit Software, PBC, Boston, MA) was utilized to run linear models that fit all covariates (age, sex, body weight, height, body mass index [BMI], kcals from vigorous activity), water consumption obtained at time points 1 and 2, extracellular water [ECW], intracellular water [ICW], total body water [TWC] obtained by BIA at time point 1 only). These models analyzed the two-way interaction of VO2max to the water variables or covariates. These models also analyzed three-way interactions of VO2max to water variables and covariates combined. A stepwise linear regression was then used, and analysis of variance (ANOVA) tests were performed. Linear regression of the significant water variables was plotted showing variations in age and sex. Results: A total of 141 individuals (65 females and 76 males), 18 to 64 years of age, were included in the secondary cross-sectional analyses. The youngest age group had the highest mean VO2max and body water content (47.8 mL/kg/minute and 98.34 L (TWC), respectively). Changes in the covariates (age, height, BMI, kcals from vigorous activity) were each found to significantly affect VO2max (all P<0.001). ECW (P=0.0005), ICW (P=0.01) and TCW (P=0.016) were significantly associated with VO2max. Water consumption at both time points were not significantly associated with VO2max. ECW had a strong positive relationship with VO2max for those 18 to 29 and ≥50 years of age. There was an inverse relationship between ICW and VO2max for those 18 to 29 years of age and those ≥50 years of age (P=0.0020 and P= 0.59, respectively). In those 18 to 29 years of age, as ICW increased VO2max increased, while for those ≥50 years of age, as ICW increased VO2max decreased. Conclusion: There were no significant associations found between water consumption and VO2max; however, significant correlations with water content assessed by BIA and VO2max were found. The significant positive relationship among ECW, ICW and VO2max, with variations by age, indicate that further research for these populations should be conducted because body water content may play a role in exercise performance. Keywords: Adult athletes, Body water content, Exercise performance, Recreational athletes, VO2max, Water consumption