Validity of BMI-based Equations for Estimating Body Fat Percentage in Collegiate Male Soccer Players: A Three-Compartment Model Comparison

The ease of calculating body mass index (BMI)-based body fat percentage (BF%) is appealing in collegiate male soccer player who have limited time availability and strict training regimens. However, research has yet to evaluate whether BMI-based BF% equations are valid when compared to a criterion multi-compartment model. PURPOSE: The purpose of this study was to compare BMI-based BF% equations with a three-compartment (3C) model in collegiate male soccer players. METHODS: Sixteen NCAA Division II male soccer players (age = 21 ± 2 years; ht = 179.0 ± 8.2 cm; wt = 78.0 ± 8.5 kg) participated in this study. BMI was calculated as weight (kg) divided by height squared (m2). BF% was predicted with the BMI-based equations of Jackson et al. (BMIJA), Deurenberg et al. (BMIDE) Gallagher et al. (BMIGA), and Womersley and Durnin (BMIWO). The criterion 3C model BF% was determined using air displacement plethysmography (BOD POD®) for body volume and bioimpedance spectroscopy for total body water. RESULTS: The BMI-based BF% equations significantly overestimated mean group BF% for all equations when compared to the 3C model (2.78 to 5.18%; all p \u3c 0.05). The standard error of estimate ranged from 4.18 (BMIDE) to 4.29% (BMIWO). Furthermore, the 95% limits of agreement were similar for all comparisons and ranged from ±7.96 (BMIGA) to 8.18% (BMIJA). CONCLUSIONS: The results of this study demonstrate that the selected BMI-based BF% equations produce fairly small SEEs and 95% limits of agreement. However, the equations also revealed systematic error and a tendency to overestimate mean group BF% when compared to the 3C model. BMI-based equations can be used as an alternative for the individual estimation of BF% in collegiate male soccer players when a more advanced 3C model is not available, but practitioners should consider adjusting for the systematic error (e.g., decrease BMIDE by 2.78%)

Validity of Four-Compartment Models when Estimating Bone Mineral Content and Total Body Water with Single-Frequency Bioimpedance

Bone mineral content (BMC) and total body water (TBW) are commonly assessed via dual energy X-ray absorptiometry (DXA) and bioimpedance spectroscopy (BIS), respectively, for a criterion 4-compartment body composition model (4CCRITERION). However, single-frequency bioelectrical impedance analysis (SF-BIA) has been proposed as an alternative for calculating BMC and TBW. PURPOSE: The purpose of this study was to compare 4C models for body fat percent (BF%), fat-free mass (FFM), and fat mass (FM) when using SF-BIA individually for the estimation of BMC (4CBMC) and TBW (4CTBW) or in combination (4CBMC+TBW). METHODS: Seventy-one men and seventy women (n=141) participated in this study (age=23±5 years). 4CCRITERION was derived using underwater weighing (UWW) for body volume (BV), BIS for TBW, and DXA for BMC. 4C prediction models were as follows: 4CBMC = UWW for BV, BIS for TBW, and SF-BIA for BMC; 4CTBW = UWW for BV, DXA for BMC, and SF-BIA for TBW; 4CBMC+TBW = UWW for BV and SF-BIA for BMC and TBW. RESULTS: The standard error of estimate (SEE) and total error (TE) was smallest for 4CBMC in men (BF% = 0.53 and 0.60%; FFM = 0.42 and 0.48kg; FM = 0.43 and 0.48kg, respectively) and women (BF% = 0.48 and 0.50%; FFM = 0.27 and 0.28kg; FM = 0.27 and 0.29kg, respectively). However, 4CTBW and 4CBMC+TBW also produced acceptable individual error in both sexes (SEEs = 1.19-1.37% and TEs = 1.44-1.83% for BF%; SEEs = 0.73-0.96kg and TEs = 1.09-1.36kg for FFM; SEEs = 0.79-1.00kg and TEs = 1.10-1.36kg for FM). CONCLUSIONS: 4CBMC produced the smallest individual error of all the 4C prediction models when using SF-BIA. However, 4CTBW and 4CBMC+TBW also produced acceptable SEEs and TEs. This indicates that a 4C model could potentially be utilized with only 2 methods (UWW and SF-BIA)