Beverage-Specific Modulation of Urinary Inflammatory Biomarkers After Endurance Running in Trained Males

Background: The differential effects of post-exercise rehydration beverages on inflammatory processes and organ protection remain incompletely characterized. This study investigated how beverages with distinct compositions influence urinary biomarkers following endurance exercise. Methods: In a randomized crossover design, eight trained male runners performed 6000 m pace running followed by consumption of 500 mL of either: water (Drink 1), hypotonic sports drink (Drink 2, 200 mOsm/L), oral rehydration solution (Drink 3, 270 mOsm/L), or modified hypotonic formulation (Drink 4, 200 mOsm/L). After 60 min, participants completed a 1000 m time trial. Urine samples were collected at baseline, post-6000 m, and post-1000 m for analysis of biochemical parameters and inflammatory cytokines. Results: No significant differences in 1000 m performance were observed between trials. Drink 3 significantly reduced creatinine and uric acid excretion compared to other beverages (p < 0.05), suggesting decreased waste product elimination. Creatinine-corrected intestinal fatty acid-binding protein values were lower with Drinks 2 and 3, indicating potential intestinal protection. Notably, Drink 4 showed modest but significant enhancement of IL-4 excretion (p < 0.05, ηp² = 0.347), demonstrating beverage-specific modulation of anti-inflammatory cytokines with moderate effect sizes. Conclusions: Different beverage formulations exert distinct effects on waste product elimination, intestinal organ damage markers, and inflammatory cytokine profiles. These findings suggest that beverage selection should be tailored to specific recovery priorities and training contexts.