Usefulness of age-adjusted equations to estimate body fat with air displacement plethysmography in male adolescent athletes.

This study was designed to examine the accuracy of air-displacement plethysmography (ADP) using Lohman's age-adjusted equations (Leq) and Siri's equation (Seq) in estimating body fat (BF) in male adolescent athletes, with the four-compartment (4C) model as reference. Subjects were 51 Caucasian boys (age, 15.5+/-1.2 years; weight, 71.0+/-11.9 kg; stature, 1.79+/-0.12 m). Comparison of means with the Wilcoxon test showed that BF estimates with Seq to be different from those with Leq and 4C model, (8.8+/-4.4 vs. 7.9+/-4.5 and 8.1+/-4.0 kg, respectively) ( p<0.001), suggesting an overestimation of BF. However, BF estimates with the Leq and with the 4C model were identical ( p>0.05). Estimates using Seq and Leq with the 4C model were similar, as shown by the 95% confidence intervals (-4.7-2.4 and -4.0-3.7, respectively). These findings suggest that in male adolescent athletes, the use of Leq improves estimates of BF by densitometry using ADP.