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We investigated the relationship between age and muscle size in both the appendicular and trunk regions of 1507 Japanese men and women aged 20 to 95 years. Seven hundred twenty-two men (young [aged 20-39 years], n = 211; middle-aged [aged 40-59 years], n = 347; and old [aged 6095 years], n = 164) and 785 women (young, n = 207; middle-aged, n = 341; and old, n = 237) were recruited for this cross-sectional study. Muscle thickness (MTH) and subcutaneous fat thickness (FTH) were measured by ultrasound at 8 sites on the anterior and posterior aspects of the body. MTH was expressed in terms relative to limb length (MTH/L) or height (MTH/Ht). Percent body fat was estimated from FTH, and fat-free mass (FFM) was calculated. In men, a graded decrease in FFM was found in all age groups. In women, FFM was similar in the young and middle-aged groups, but was lower in the oldest group. Age was significantly and inversely correlated with FFM in men (r = - 0.358, p < 0.01), but not in women (r = -0.08). On the other hand, age was strongly and inversely correlated with quadriceps MTH/L (men, r = -0.529; women, r = -0.489; both p < 0.001) and abdomen MTH/Ht (men, r = -0.464; women, r = -0.446; both p < 0.001) in both men and women, while there were only weak correlations between age and other lower limb and trunk sites. Our results indicated that sarcopenia is observed as a site-specific loss of skeletal muscle mass, especially for the quadriceps and abdominal muscles, in Japanese men and women aged 20 to 95 years. |
