Body fat and muscle thickness in Japanese and Caucasian females.

Fat and muscle thicknesses were measured at eight sites by B-mode ultrasonography on 36 Japanese (age = 25.9 ± 1.9 years; mean ± SD) and 56 Caucasian females (25 ± 2 years) to compare the distribution of these tissues. The eight sites were the biceps, triceps, forearm, subscapular, abdomen, quadriceps, hamstring, and calf. Hydrostatically determined body density, corrected for residual lung volume, was similar (P > 0.05) for Japanese (1.048 ± 0.008 g · ml ) and Caucasians (1.050 ± 0.009 g · ml ). However, in part because of their greater body mass, Caucasians had significantly more (P < 0.05) fat mass (FM; 12.5 ± 3.2 kg) and fat-free mass (FFM; 45.1 ± 5.1 kg) compared to the Japanese (FM = 11.1 ± 2.3 kg, FFM = 38.0 ± 3.5 kg). From the results of a subsample analysis of a group matched for stature and body mass, Japanese women had a greater abdominal fat thickness than Caucasians, but had less fat thickness at the triceps and hamstring sites. Caucasians had greater muscle thicknesses than Japanese at all sites except for abdomen, hamstring, and calf. The ratio of fat thickness to FM · stature was higher on the trunk (P < 0.001) in Japanese (6.650 ± 1.721 mm · g × 10 ) than in Caucasians (4.713 ± 1.441 mm · g × 10 ). The ratio of muscle thickness to FFM · stature was higher (P < 0.001) in Caucasians than in Japanese at the upper extremity and trunk sites. These results suggest that the distribution of subcutaneous fat might be specific to ethnic origin, and that Japanese women have less muscle development than Caucasians even when matched for stature and body mass. © 1994 Wiley-Liss, Inc.