Dual-Energy X-Ray Absorptiometry Investigation of Fat Mass and Lean Mass in 193 Male Elite Youth Soccer Players

Background: Youth soccer is practiced worldwide. However, body composition during youth soccer practice has received limited attention despite its well-known impact on performance. Methods: Dual-energy X-ray absorptiometry (DXA) estimated whole-body and regional fat and fat-free soft tissue mass, and percent fat mass in a large sample (n = 193; 172 White, 21 Black) of male elite youth soccer players aged 14–19 years competing in an Italian Serie A Club. The role of playing position in shaping body composition was also explored. Results: Black players had higher appendicular fat-free mass index (p = 0.009) and lower total body less head (TBLH) fat mass index (p = 0.050) than White players. Within the entire sample of players, analysis of covariance (ANCOVA) conducted using several confounding variables as covariates showed a statistically significant effect of playing position for TBLH fat-free soft tissue mass (p = 0.049) and appendicular fat mass (p = 0.039), with the goalkeepers showing higher appendicular fat mass than defenders (p = 0.031). Also, playing position showed a significant effect on TBLH fat-free mass index (p = 0.044). Effect sizes for statistically significant ethnic differences ranged from η2p = 0.02–0.06, whereas positional effects ranged from η2p = 0.05–0.21, indicating that several, but not all, observed effects were small in magnitude. Descriptive percentiles for demographic and body composition variables and indices were calculated in three two-year age classes for White players only, because of the limited number of Black players. Conclusions: In our cross-sectional, single-club sample of male elite youth soccer players, DXA analysis provided descriptive data on fat- and lean-mass variables overall and according to playing position. Findings related to ethnicity should be interpreted cautiously because of the limited number of Black players. The percentiles provided for White players may serve as descriptive benchmarks for youth players.