Effects of bone mineral content and density on accuracy of body fat measurement by underwater weighing.
- VernacularTitle:水中体重秤量法による体脂肪率測定の精度に及ぼす骨ミネラル量，骨容度の影響
- Author:
HIDEYUKI TOBE
;
SHIGEHO TANAKA
;
MICHIKO KODA
;
TAKASHI SATAKE
;
TAKAYUKI HOSOI
;
HAJIME ORIMO
- Publication Type:Journal Article
- Keywords:
underwater weighing;
DXA;
fat-free body density;
bone mineral content;
bone mineral density
- From:Japanese Journal of Physical Fitness and Sports Medicine
1996;45(5):503-509
- CountryJapan
- Language:Japanese
-
Abstract:
Underwater weighing is based on the assumption that fat-free body density is roughly constant among humans. This assumption should be examined, because fat-free body density may in fact depend on the bone mineral and water contents of the body, with fat excluded. The purpose of this study was to investigate the effects of bone mineral content (BMC) and density (BMD) on the accuracy of body fat measured underwater. The subjects were 12 young men (25.1±3.7 years, mean ± SD), some of whom were trained athletes. BMC and BMD were measured by dual-energy x-ray absorptiometry (DXA), as was body fat, as a percentage of body weight; this method is not based on the assumption that fat-free body density is the same in different individual. Body fat as a percen tage of body weight was measured underwater, also. Body fat measured by DXA was significantly correlated with that found by underwater weighing (r = 0.83, p<0.01), as expected, but the mean body fat found by DXA was 4.3% higher. The differences between results by the two methods for individuals were from -11.5% to 2.7%, and the differences were negatively correlated with BMC/fat-free weight (FFW ; r=-0.82, p < 0.01) and BMD (r=-0.85, p<0.01) . Fat-free body density ranged from 1.097 to 1.111 g/cm3because BMC/FFWs varied with the individual. We concluded that individual differences in BMC/FFW and BMD affected the fat-free body density. The variations in fat-free body density would give rise to systematic errors in body composition measured underwater.
