Urinary Metabolic Profiles Before and After the Winter Training Season in Female Soccer Players

Background/Objectives: Female soccer players differ from males in body composition, muscular strength, and hormonal fluctuations, which may influence performance, fatigue, recovery, and injury risk. This study aimed to characterize metabolic changes following a winter training season (WTS) and estimate an appropriate recovery period using urinary metabolomics. Methods: Urinary metabolites in female soccer players were analyzed before, and after 1 and 7 days of WTS using nuclear magnetic resonance (NMR) spectroscopy combined with multivariate analysis. Results: A total of 84 metabolites were identified in urine samples, and distinct group separation was observed by partial least squares discriminant analysis (PLS-DA) in targeted profiling. Among these, 13 metabolites, including adenine, alanine, citrate, creatine, creatine phosphate (PCr), formate, glutamine, glycine, malonate, mannitol, taurine, trimethylamine N-oxide (TMAO), and urea, showed significant changes relative to pre-WTS. Conclusions: Of the identified metabolites, seven metabolites showed significant alterations at 1 day post-WTS and tended to recover toward baseline levels by day 7. Alanine, PCr, formate, glutamine, glycine, and malonate showed decreased levels, whereas taurine exhibited the opposite trend. Although these metabolites tended to recover toward baseline by day 7, complete metabolic recovery was not observed, suggesting that recovery following WTS may require longer than 7 days.