ASSOCIATION BETWEEN DIET, PERFORMANCE, AND HORMONAL CHANGES IN DIVISION I MALE SOCCER PLAYERS

Abstract

PURPOSE: The condensed preseason and match fixture in collegiate soccer impacts hormonal status, though the role of diet on this response is less studied. The purpose of this study was to assess athlete adherence to diet logs and determine relationships between diet and hormonal changes in collegiate soccer players. METHODS: Male collegiate soccer players (N=22) participated in preseason testing to assess body composition (%BF, FFM) and VO2max. Energy expenditure (EEE) was measured during all on-field activities via heart rate monitoring. Blood draws were conducted during preseason and 45 d later for analysis of leptin (LEP), thyroid hormones (TSH, T3, T4), free cortisol (CORT), free testosterone (TEST), and IGF-1. Two 3-day diet logs were completed 21 d apart. Pearson product correlations and hierarchical regression were used to assess relationships between performance, diet, and biomarkers at α=0.05. RESULTS: Four (18.2%) participants completed all six days of diet logs. As such, individuals who completed ≥3 d were included in dietary analyses (n=9). %BF negatively correlated with ΔTSH (r=-0.47, P=0.04). Protein intake correlated positively with FFM (r=0.75, P=0.02) and negatively with ΔLEP (r=-0.74, P=0.02) and ΔTSH (r=-0.74). Moderate correlations were seen between ΔLEP and ΔIGF-1 (r=0.41, P=0.04) and ΔCORT and ΔTEST (r=0.41, P=0.03). When controlling for EEE, protein intake accounted for variance in ΔLEP (R2=0.51; P=0.04) and ΔTSH (R2=0.60; P=0.02), and FFM accounted for variance in TSH (R2=0.20; P=0.06). No relationships were found with VO2max, T3, T4, and other measures. CONCLUSIONS: These findings show the limited utility of implementing diet logs in this population. The correlations between different hormones show the inherent associations between metabolic status, stress, and anabolism. Overall, the roles of body composition and protein intake on LEP and TSH, hormones associated with energy availability, suggests that protein may be a unique and understated factor in this equation. Funding provided by Quest Diagnostics