Somatotype affects lean body mass estimation with bioelectrical impedance analysis in young athletes

The accuracy of body composition assessments with bioelectrical impedance (BIA) based devices may be affected, besides the well-known factors (e.g. hydration status), by factors which are related to anthropometric characteristics.

The aim of this study was to investigate the effects of somatotype on body composition estimation, especially on lean body mass (LBM), using BIA.

539 male (mean age: 15.8 ± 2.5 years) and 121 female young athletes (mean age: 16.5 ± 3.2 years) were included. Body composition was assessed by BIA and dual-energy X-ray absorptiometry (DXA). Somatotype was determined using the Heath-Carter method (endomorphy, mesomorphy, and ectomorphy). Intergroup differences were analysed with one-way and repeated measures analysis of variance.

On average, BIA underestimated percent body fat (PBF) by 7.6% and overestimated LBM by 3.9 kg compared to DXA. Significantly smaller bias between the two methods was found in mesomorphy for both LBM and PBF. The ectomorph group demonstrated the largest underestimation in PBF, while the endomorph group the largest overestimation in LBM. Segmental analysis revealed larger overestimation of LBM of the lower limbs in ectomorphy.

Findings suggest that LBM estimates are affected by somatotype with mesomorphy reducing, while ectomorphy and endomorphy increase, the estimation bias between BIA and DXA.