A Comparison of Body Density and Percent Body Fat Using Functional Residual Capacity and Residual Volume and Development of Immersed Functional Residual Capacity and Residual Volume Prediction Formulas

Abstract

This study developed prediction formulas (PF) for residual volume (PRV) and functional residual capacity (PFRC) using the variables age (A), height (Ht), weight (Wt), chest depth (CD), and smoking history (SH)in 100 male subjects between the ages of 18-69 years. A and Ht were the only variables which contributed significantly to PRV. A, Ht, and Wt were the only variables to contribute significantly to PFRC. A test-retest correlation between two trials of RV (r=.99) and FRC (r=.98) determinations indicated that reliable measures were taken by the closed circuit oxygen dilution technique. Through the use of multiple step-wise regression the following PRV and PFRC formulas were developed: PRV (liters)=.0260376(A) + .0256005(Ht) - 3.89794 PFRC (liters) = .0493365(Ht) + .0116958(A) - .00919313(Wt)-6.20966 The standard error of estimation (S.Y.E.) of the PRV and PFRC formulas (241 and 403 mls, respectively) were all lower than those reported by Boren et al . (1966) (B), Crapo et al . (1982) (C), Goldman and Becklake (1959) (GB). and Grimby and Soderholm (1963) (GS). The variation ( R ~ ) attributed to the independent variables was .72 and .4l for PRV and PFRC, respectively. These R' values were higher than those reported by B, C, and GS. Using the data obtained in this study, an ANOVA with repeated measures followed by a Scheffe' post hoc test determined significant differences (p<.05) between PRV and the PF of C and GB. Significant differences (p<.05) were also determined between PFRC and the PF of B, C. GB, and GS. A further purpose of this study was to compare body density (BD) and percent body fat (%BE) determined at the RV and FRC lung volume maneuvers in the hydrostatic weighing procedure. There was no significant difference (p>.05) between BD at RV and FRC. There was, however, a significant difference (p<.05)in %BF a t RV and FRC.