Hydrostatic weighing was performed at both residual volume and total lung capacity (both measured on land) in 28 prepubertal males (x age = 8.3 ± 1.1 yrs.). It was hypothesized that because pre-pubertal males have relatively small total lung capacity, the effects of hydrostatic pressure during hydrostatic weighing at total lung capacity should not be as great as in adults. Small but statistically significant differences (p<.05) in total body volume (corrected for lung volume) were observed with the use of hydrostatic weighing at residual volume (27.19 ± 6.28 liters) vs hydrostatic weighing at total lung capacity (26.95 ± 6.23 liters) (r = .99, sy x = 0.33 liters). When total body volume was converted to body density, significant mean differences were observed (body density at residual volume = 1.057 ± 0.016 g/ml, body density at total lung capacity = 1.066 ± 0.018 g/ml, p<.05.). The predictability of body density at residual volume from body density at total lung capacity was considerably lower than observed for total body volume (r = .65, sy x = 0.0129/ml). A similar relationship was observed when body density was converted to percent body fat (r = 0.66, sy x = 5.57%). Thus, the use of hydrostatic weighing at total lung capacity in pre-pubertal males results in a slightly, but statistically significant, lower determination of total body volume compared to hydrostatic weighing at residual volume. The reduced correlation between body density and percent fat at residual volume, and body density and percent fat at total lung capacity, may be because the mean difference of 0.24 liters between total body volume at residual volume and total lung capacity exerts a greater influence in the conversion of total body volume to body density in prepubertal males (where total body volume is approximately 27 liters) than it would in adults (where total body volume can range from 60-90 liters). It is concluded that the use of hydrostatic weighing at total lung capacity for body density determination is not acceptable in a research or clinical setting when applied to pre-pubertal boys.
Weltman, Arthur; Janney, Carol; Huber, Roger; Rians, Clark B.; and Katch, Frank I.
"Comparison of Hydrostatic Weighing at Residual Volume and Total Lung Capacity in Pre-Pubertal Males,"
1, Article 6.
Available at: https://digitalcommons.wayne.edu/humbiol/vol59/iss1/6