Abstract
Background: Body composition and hydration status, particularly the balance between intracellular (ICW) and extracellular (ECW) water compartments, are critical factors influencing performance and aesthetics in competitive bodybuilding. Despite their significance, limited research has explored sex-based differences in hydration strategies and their impact on competitive outcomes. Objectives: This study aimed to characterize and compare ICW and ECW distribution, as well as their relationship with key physiological parameters, between male and female elite bodybuilders during an international competition. Methods: A total of 34 elite bodybuilders (18 males and 16 females) participated in this cross-sectional study. Body composition was assessed using multifrequency bioelectrical impedance analysis (BIA). The parameters evaluated included total body water, ICW, ECW, and phase angle (PhA). Differences between sexes were analyzed using Student's t-tests, with statistical significance set at p < 0.05. Results: Significant sex-based differences were observed in water compartment distribution. Male bodybuilders exhibited higher ICW values (33.1 ± 2.8 L vs. 25.7 ± 2.5 L; p < 0.001) and PhA (8.2 ± 0.7 vs. 7.0 ± 0.9; p < 0.05), indicating greater muscle mass and cell integrity. In contrast, females had a higher ECW-to-total body water ratio (42.7% vs. 39.5%; p < 0.05), likely influenced by hormonal and metabolic factors. These findings suggest that sex-specific physiological characteristics should be considered when developing hydration and competition strategies. Conclusions: The study highlights the importance of sex-specific approaches to hydration and body composition management in bodybuilding. The observed differences in ICW and ECW distributions underscore the need for individualized training, nutrition, and hydration strategies to optimize competitive performance while maintaining athlete health. Future research should focus on longitudinal assessments to better understand hydration dynamics across different stages of competition preparation.