Effect of immersion in water on residual volume in college-age men and women: a thesis ...

Health care professionals require accurate measurements of body composition and the hydrostatic weighing method is widely used as a reliable technique. Hydrostatic weighing measures body density accounting for an individuals residual volume (RV). To determine differences of RV measured in air (RVA) and in water (RVW), college-age men and women (n=51) were randomly assigned to one of four groups: female RVA, female RVW, male RVA, or male RVW. To account for possible gender differences with protocol (RVA vs. RVW) male and female subjects were treated as separate groups. RVW subjects began the first two trials in water followed by two trials out of water. If RV measures differed by more than 200 ml between the first two trials either in water or in air, a third or fourth trial was completed until two RV measures were within 200 ml of each other. The two trials were then averaged to determine the RVW. The same procedure was used for RVA subjects. RV was determined by the closed circuit helium dilution method. A 2-factor repeated measures ANOVA revealed that there was no statistically significant interaction between genders and protocols, a statistically significant difference between genders, and a statistically significant difference between protocols (RVA vs. RVW). The RV mean decreased with immersion in water among college-age subjects. A decrease in RV will have a marked increase in estimation of percent body fat. Therefore, the results of this study indicate that measuring RV during immersion in water on college-age men and women, to accurately assess body composition, is a valid and recommended protocol