Influence of anthropometric parameters on the body composition measured by bioelectrical impedance analysis or DXA in children

Abstract

Aim: To investigate the influence of anthropometric measures (skinfold thicknesses, girths, lengths and breadths/lengths) on (1) the whole body impedance and impedance index and (2) the body fat mass measured by means of DXA in children.

Methods: Nine skinfolds, 13 girths, eight lengths and eight breadths/lengths were measured in 26 boys and 27 girls, 11-12 y of age. The somatotype components-endomorphy, mesomorphy and ectomorphy--were assessed according to the method of Carter and Heath. Body impedance at 50 kHz was measured (Multiscan 5000, Bodystat Ltd, UK) and impedance index (height2 / impedance) was calculated. Four body components-total body fat mass and separate hands, legs and trunk fat mass--were determined using DXA.

Results: Skinfold thicknesses did not influence body impedance or impedance index according to stepwise multiple regression analysis. Impedance index was influenced more by the girth measures than was body impedance. The leg length measures highly influenced the impedance index (50-81%, R2 x 100). Different breadth/length parameters influenced body impedance and body impedance index (21-49%). Mesomorphy influenced body impedance only in boys (35%). Body fat mass measured by DXA was highly dependent on the measured skinfold thicknesses (59-92%). The influence of lengths and breadths/lengths on the total fat mass was significant (25-49%). Endomorphy characterized total fat mass as 86% and 52% in boys and girls, respectively.

Conclusion: Variation in anthropometry highly determined the variance observed in impedance in children, and the girths were the best predictors of impedance. Selected skinfold thicknesses highly predicted fat mass measured by DXA for total body, trunk, arms and legs.