How Bigs Get Bigger - Body Composition Changes In Collegiate Football Players Across Aseason

Cross-sectional data collected on professional football players suggest that players weighing >114 kg accumulate fat at a greater proportion of total mass (Bosch TA 2014). PURPOSE: To (1) assess changes in total, lean, and fat mass in collegiate football players; (2) assess relationships between lean mass versus fat mass changes by player position groups; and (3) determine thresholds where fat accumulates at a greater proportion of total mass. METHODS: College football players underwent body composition testing using a dual energy x-ray absorptiometry (DXA) scan in August 2022 (pre) and March 2023 (post). Players were sub-divided into three position groups: BIGS (offensive and defensive lineman), SKILLS (receivers, running backs, safeties, and cornerbacks), and COMBOS (all other players). Differences in player group positions were analyzed using 1-way ANOVA. Change = (post - pre). RESULTS: 80 players, with a mean age of 19 ± 1 years, height of 1.84 ± 2.7 m, and weight of 100 ± 20kgs, completed testing. BIGS were the largest and SKILLS the smallest players with regards to total mass (F = 103.1; r2 = 0.73; p < 0.001), lean mass (F = 73.5; p < 0.0001; r2 = 0.66), body fat% (F = 51.8; p < 0.0001; r2 = 0.58) and bone density (Z-score F = 9.11; p = 0.0003; r2 = 0.19). Non-significant pre to post season increases seen in total mass (2.9 ± 4.0 kg), lean mass (0.9 ± 2.5 kg), body fat% (1.1 ± 1.6%), and bone density (z-score: 0.09 ± 0.18). Significant relationships noted between changes in lean mass vs. changes in fat mass (r2 = 0.09; p = 0.006) and was strengthened when the BIGS were removed (r2 = 0.29; p < 0.001 SKILLS+COMBOS only). Players with a total body mass > 110 kg, and a lean mass > 91 kg, gain fat in greater proportion of total mass (see Figure). CONCLUSIONS: Modest increases in total (~3%), lean (~1%), fat (~1%) and bone (~1%) mass seen across a season. Collegiate football players weighing >110 kg, with >91 kg of lean mass, accumulate fat at a greater proportion of total mass.