Comparison of Three Hydrostatic Weighing Methods

Abstract

This study compared hydrostatic weighing (HW) at residual volume (RV), total lung capacity (TLC)-dry and TLC-wet in the determination of body density (00) and percent body fat (%BF). Considering the comfort of the submerged Ss, it was the dim of this study to establish a HW method which was reliable. Student volunteers included 44 competitive swimmers (25 females; 19 males) and 55 noncompetitive swimmers (31 females; 24 males) ages 17-34. Residual volume was determined by the open circuit nitrogen washout technique. Dry and wet measurements of forced vital capacity (FVC) and TLC were obtained from all Ss to determine appropriate measurement in application to BD and %BF calculations . All Ss underwent HW at RV and TLC. Three BD and %BF were calculated for Ss by applying lung measurements of RV, TLC-dry and TLC-wet. Ss noted method preference; at RV, TLC or neither. A 3 way ANOVA with repeated measures followed by a Scheffe' Post Hoc Test was used to analyze the following variables: FVC-dry, FVC-wet, TLC-dry , TLC-wet, BD and %BF by HW at RV, TLC-dry and TLC-wet. A Chi Square analyzed Ss HW method preference. There was a sig (p < .01) reduction in FVCwet and TLC-wet when compared to those measurements dry in Ss combined. There were sig (p<.01) diff between HW at RV vs HW at TLC-dry and HW at RV vs HW at TLC-wet ('F %BF differences = 3.64% and 1.77%, respectively) in Ss combined. %BF with HW at RV > at TLC-wet > at TLC-dry. A1 1 subgroups and Ss combined preferred HW at TLC (p<.05). The sig diff in HW methods may be due to an underestimation of RV during HW at RV and an overestimation of TLC during HW at TLC-dry. It was concluded that HW is not equivocal at/RV, TLC-dry and TLC-wet. HW at TLC-wet may be most accurate in %BF determination. Previous research supports the conclusion that pulmonary air trapping was reduced or eliminated and TLC was truly represented during HW at TLC-wet.