Measured specific gravity, predicted specific gravity and total body water relationships in normal young men.

Abstract

The purpose of this investigation was to compare measured specific gravity values with predicted specific gravity values from skinfold measures using various prediction formulae. Skinfold measurements were made of the unbilicus, triceps and chest of each of twenty-six young adult males. Specific gravities were predicted from the measurements using different formulae. Specific gravity was then determined for each subject by underwater weighing. Total body water was determined for each subject using the tritium dilution technique. Predicted specific gravity values from the male triceps skinfold formula were not significantly different from actual specific gravity values. Predicted specific gravity from the male umbilicus skinfold measures and from the male chest skinfold formula were significantly different from actual specific gravity. Specific gravity was also predicted from a formula for females and all of these predicted specific gravity values were significantly different from actual specific gravity. Estimates of total body water revealed that body water content averaged 53 per cent of body weight and a range of 11 per cent. This variation is important and must be considered when small samples are used for measuring specific gravity by the water displacement technique.