ABSTRACT
Body composition assessment has become an integral part of athletes' training schedules. Questions remain concerning the accuracy of various methods to track body composition changes over a competitive year cycle. The purpose of this study was to compare various methods of tracking body composition across a college women's basketball season. Fourteen Division II women (age = 20.1 ± 1.2 y) were measured prior to the season (T1), after pre-season conditioning (T2), at mid-season (T3), and at the end of the season (T4) using skinfolds (SKF), two bioelectric impedance analysis (BIA) devices, and dual-energy x-ray absorptiometry (DXA). BIA devices were hand-to-hand (H-BIA) and foot-to-foot (F-BIA) single-frequency models. SKF were used to estimate %fat using four prediction equations. A method × trial factorial ANOVA on %fat with repeated measures over the second factor indicated that all methods except the Durnin-Womersley SKF equation were significantly lower than DXA. Across trials, DXA %fat at T1 (25.3 ± 4.7%) was significantly higher than at T2 (24.3 ± 4.6%), T3 (24.6 ± 4.6%), and T4 (24.4 ± 5.1%). Agreement between DXA and the other methods were moderate (r = 0.48 - 0.86). Rank-order correlations of DXA with the other methods to compare team order indicated H-BIA (rho = 0.67 - 0.78) and F-BIA (rho = 0.62 - 0.77) provided comparable agreement, with SKF methods having lower agreement for team order (rho = 0.46 - 0.73). Compared to the DXA standard, a foot-to-foot BIA device may provide adequate but significantly lower relative tracking of %fat across a women's basketball season.
ABSTRACT
Bioelectric impedance analysis (BIA) devices are commonly used to estimate percent body fat (%fat), although validation of their accuracy varies widely. The purpose of this study was to assess the validity of four commonly used BIA devices compared to dual-energy X-ray absorptiometry (DXA). College-aged men (n = 29, age = 19.7 ± 1.2 y, weight = 76.9 ± 12.5 kg) and women (n = 31, age = 20.5 ± 0.8 y, weight = 61.5 ± 9.2 kg) were evaluated for %fat using four single-frequency (50 mHz) BIA devices and DXA. A gender × device repeated measures ANOVA indicated some less expensive BIA devices produced %fat values that were not significantly different from DXA. A thumb-to-thumb BIA device produced the closest values in men (21.9 ± 6.6%) and women (32.1 ± 5.3%) compared to DXA (20.6 ± 6.1% and 30.3 ± 5.4%, respectively). The two more expensive BIA devices significantly underestimated in men (14.7 ± 5.8% and 17.0 ± 5.6%) and women (23.3 ± 4.2% and 23.3 ± 4.2%) compared to DXA. Interclass correlation coefficients with DXA were higher for the more expensive devices in men (ICC = 0.899 and 0.958) than the less expensive devices (ICC = 0.681 and 0.730). In women, all BIA devices showed moderate correlations with DXA (ICC = 0.537 to 0.658). Despite the convenience of simple BIA devices, their use in estimating body composition in young men and women might be questionable due to large variations in the differences between DXA and each device in this study.
