Effects of bone mineral content and density on accuracy of body fat measurement by underwater weighing / 体力科学

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/cm<SUP>3</SUP>because 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.

Human body composition determined by cadaver dissection / 体力科学

Sixty-two embalmed cadavers of elderly Japanese individuals, ranged in age from 44-98 years (48 males, 14 females), were completely dissected, and the weights of skin plus subcutaneous adipose tissue (SSATW) and Triceps Surae Muscle (TSMW) determined. Then subcutaneous adipose tissue free weight (SSATFW) was determined by subtracting SSATW from body weight (BW) .<BR>SSATW and percentage of SSATW relative to BW in females (8.9 kg, 19.8%) were larger than those in males (6.1 kg, 12.7%) . On the other hand, TSMW and percentage of TSMW relative to BW in males (313.6 g, 0.65%) were larger than those in females (210.6g, 0.49%) . BW, SSATFW, TSMW were highly correlated (p<0.01) with each other in males. However, in females, TSMW was not significantly correlated (p>0.05) with those variables. The slopes of regression lines for SSATW against BW and SSATFW for females were about twice as steep as those for males.<BR>From these results, it was suggested that females carried a higher proportion of their adipose tissue externally than males and relationship between muscle weight and inner adipose tissue weight in females was more variable than in males.

Effect of physical activity in daily life on muscle weight and relative weight of the m. triceps surae / 体力科学

In this paper, effects of physical activity in daily life on m. triceps surae were considered comparing the cadavers with decubitus with those without decubitus on muscle weight and relative muscle weight. The muscles were dissected from 18 cadavers (13 males and 5 females) aged 36 to 90 which were preserved in a 10% formalin solution for about one year. Immediately after the removal, weights of gastrocnemius and soleus were measured.<BR>Mean values of the muscle weights of soleus, gastrocnemius and combined total were heavier in male than in female. Those of the relative weights of soleus were larger than those of gastrocnemius in both sexes. The muscle weights showed remarkable inter-individ-ual variations and sexual differences. The decubitus group (non-active group) showed lighter muscle weight than the normal group did in both sexes. However, there were no differences in the relative muscle weight between both groups in both sexes.<BR>The rate of lack of m. plantaris was 11.1%.<BR>From these results, it was suggested that the relative muscle weight might not be influenced by physical activity in daily life but the muscle weight might change consid-erably related to it.

Effect of physical exercise on physical growth and maturation / 体力科学

In order to investigate an effect of exercise on physical growth and maturation, physical characteristics (height, weight, chest girth, bi-acromial diameter, bi-iliac diameter and span) and skeletal age were measured for 34 boys of control group and 37 boys of soccer group. Skeletal age was evaluated from hand wrist radiographs by TW II method.<BR>Result showed that the values of physical characteristics in the control group were larger than those in the soccer group, but the differences were not statistically significant. Mean skeletal age in each age group of the soccer group closely approximated the chronological age, but that in the control group was inclined to proceed earlier than the chronological age. The correlations of all the physical characteristics with skeletal age were higher than with chronological age in both groups. Those correlations with chrono-logical age in the soccer group were lower than those in the control group.<BR>Based on the values of the subjects in this study, this fact leads to the conclusion that skeletal age is in fact a better predictor of physical characteristics than chronological age is. Physical characteristics of the boys in the soccer group correlate higher with skeletal age than with chronological age. In relation to the skeletal maturation, each physical characteristics in the control group shows a similar growth. In the soccer group, weight and chest girth show differences of growth from other physical characteristics.