Validity Of Bia And Skinfolds For The Measurement Of Body Composition In Collegiate Gymnasts

Body composition (BC) is a frequently assessed component of health-related fitness. A variety of laboratory methods including dual-energy x-ray absorptiometry (DXA) and field methods including skinfolds (SKF) and bioelectrical impedance analysis (BIA) can be used to measure BC. PURPOSE: To determine the validity of SKF and BIA for estimating percent body fat (% fat) in female collegiate gymnasts. METHODS: Participants were 95 female collegiate gymnasts [age 19.43 (1.2) yrs., height 1.61 (0.06) m, body mass 61.76 (6.9) kg, and BMI 23.9 (2.4) kg/m2]. Participants’ % fat was estimated using SKF (Lange calipers) and BIA (InBody 230), and then compared to DXA, which served as the reference value. All participants were tested in the hydrated state [1.016 (0.01), Urine Specific Gravity]. The validity of the BIA and SKF estimates was based on the evaluation of each method versus the reference value from the DXA by calculating the mean difference, standard error of the estimate (SEE), and coefficient of determination (R2) from linear regression analysis. Repeated measures ANOVA was used to determine overall and pairwise differences among SKF, BIA, and DXA. RESULTS: The mean and standard deviation % fat results were as follows: SKF = 24.26 (6.15), BIA = 21.91 (4.36), and DXA = 25.28 (3.90). Simple linear regression analysis for BIA using DXA as the reference variable indicated an R2 value of 0.143 and SEE of 4.137. Simple linear regression for SKF using DXA as the reference variable indicated an R2 of 0.010 and SEE of 5.149. A repeated measures ANOVA with a Greenhouse-Geisser correction determined that mean % fat differed statistically significantly among the three estimates (F (1.542, 144.990) = 26.069, P < 0.001). Post hoc analysis with a Bonferroni adjustment revealed that % fat estimates were significantly different between DXA and BIA [3.366 (95% CI, 2.531 to 4.201), p < 0.001] and between SKF and BIA [2.351 (95% CI, 0.945 to 3.757), p < 0.001], but not between DXA and SKF [1.015 (95% CI, -0.169 to 2.200), p = 0.118]. CONCLUSIONS: In this sample of female collegiate gymnasts, the SKF % fat estimate provided an accurate assessment of BC. However, the BIA analyzer significantly underestimated % fat. SKF can be recommended for estimating % fat in this population based on this analysis.