Validation of New Skinfold Prediction Equation Based on Dual-Energy X-Ray Absorptiometry for Women

Abstract

There is a high demand for affordable body composition assessments of body fat and fat free mass. Research has demonstrated that skinfold prediction equations recommended by the American College of Sports Medicine (ACSM) underestimate body fat percentage (%BF). PURPOSE: The purpose of this study was to validate an alternative equation for women created from dual energy x-ray absorptiometry (DXA). The DXA criterion (DC) equation is: %BF= -6.40665 + 0.491946(S3SF) - 0.00126(S3SF)2 + 0.12515(hip) + 0.06437(age); (S3SF = sum of triceps, suprailiac, thigh; hip = circumference in cm; age = years). METHODS: Anthropometrics (skinfolds and circumferences) and a DXA scan were completed on 78 women (mean ± SD) [age: 28.0 ± 10.1 yr., height: 165.1 ± 5.9 cm, mass: 63.5 ± 10.5 kg., BMI: 23.2 ± 3.2 kg/m2]. The three Jackson-Pollock skinfold prediction equations (JP7, JP3a, and JP3b) and the DC equation were compared to DXA %BF. RESULTS: Two-way ANOVA with repeated measures detected significant differences (p < 0.05) in the %BF with post hoc-comparisons revealing significant differences among JP7 (21.4 ± 5.8), JP3a (22.3 ± 5.9), and JP3b (22.7 ± 5.7) as compared to the DXA (26.6 ± 5.4). No significant difference existed between DC %BF (26.6 ± 5.9) and DXA %BF (26.6 ± 5.4) (p = 1.0) and the two assessments were highly correlated (R = 0.87). The standard error of the measurement for the DC equation was low (2.98%). CONCLUSION: The DC equation more accurately predicted %BF across a general population of women than the recommended ACSM equations. Practitioners should consider its use and exercise caution when using older equations since they may yield lower %BF compared to DXA.