The current study examined the influence of player position on the agreement between multi-frequency bioelectrical impedance analysis (MfBIA) and dual X-ray absorptiometry (DXA) when assessing total and segmental percent body fat (BF%), fat mass (FM), and fat-free mass (FFM) in NCAA Division I collegiate football athletes. Forty-four male collegiate athletes (age=19+/-1 yrs; height=1.9+/-1.0 m; weight=106.4+/-18.8 kg) participated. Player positions included: offensive linemen (OL; n=7), tight ends (TE; n=4), wide receivers (WR; n=9), defensive linemen (DL; n=6), defensive backs (DB; n=8), linebackers (LB; n=6), and running backs (RB; n=4). Total and segmental body composition measured using MfBIA were compared with values obtained using DXA. Compared to DXA, MfBIA underestimated BF% (3.0+/-3.8%), total FM (2.5+/-4.3 kg), arm FM (0.4+/-0.8 kg), arm FFM (1.4+/-0.9 kg), leg FM (2.8+/-2.0 kg), and leg FFM (5.4+/-2.4 kg) (all p<0.001; arm FM p=0.002) and overestimated total FFM (-2.4+/-4.5 kg) (p<0.001). Limits of agreement (LOAs) were: +/-7.39% (BF%), +/-8.50 kg (total FM), +/-1.50 kg (arm FM), +/-1.83 kg (arm FFM), +/-3.83 kg (leg FM), +/-4.62 kg (leg FFM), and +/-8.83 kg (total FFM). No significant differences were observed between devices for trunk FM (-0.3+/-3.0 kg; p = 0.565) and trunk FFM (0.4+/-2.4 kg; p=0.278), with LOAs of +/-5.92 kg and +/-4.69 kg, respectively. Player position significantly affected all between-device mean body composition measurement differences (adjusted p<0.05), with OL demonstrating the greatest effect on each variable. Therefore, MfBIA does not appear accurate in examining between-player body composition in college football players.
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