抄録
The purpose of this study was to investigate the ethnic differences in the body composition, thickness of subcutaneous fat and muscle between Japanese and American white females. Thirty-six Japanese (aged 20-30 years) and 42 American white females (aged 20-29 years) served as subjects. Percentage of fat weight (%fat) and fat free weight (FFW) were assessed by hydrostatic weighing. Subcutaneous fat and muscle thickness were measured by using B-scan ultrasound equipment with a 5MHZ transducer at eight sites : forearm, biceps, triceps, subscapular, abdomen, quadriceps, hamstrings and posterior calf. There were no significant differences in %fat between Japanese and American subjects. However, American subjects had significantly higher values in FFW compared to Japanese. The Americans showed higher muscle thickness than Japanese at every site and higher fat thickness of biceps, triceps and hamstrings compared to Japanese subjects. For fat thickness at the abdomen, however, Japanese indicated siginificantly higher values than American. In both Japanese and Amer-icans, relative values of fat weight (FW) and FFW per unit of height2 were significantly related to each of the sum of fat and muscle thicknesses obtained from every measurement site respectively. There were no differences in fat thickness at a given FW/height2 between Japanese and Americans. However, Americans showed higher values in muscle thickness than Japanese even at the Same level of FFW/height2. Therefore although ethnic differences in fat and muscle thickness are related to that of FW and FFW respectively, Americans are superior to Japanese in muscle development. There were no significant differences in upper/lower extremity ratio of fat and muscle thickness between Japanese and Americans.
