Following CT observation of the hip muscles on the upper margin of the pelvic symphysis, we discussed the relationship of body movements with aging. The muscles of 137 healthy adults (76 males, 61 females) were studied: gluteus maximus, gluteus medius, tensor fasciae latae, iliopsoas, rectus f emoris, sartorius and pectineus. Cross-sectional areas (CSA) showed the gluteus maximus to be the largest (60%) of the whole muscular CSA; next were the gluteus medius and the iliopsoas (10%), the tensor fasciae latae (6%), and the remaining muscles (5%) . Relative values were compared to males in their 20s and subsequent decades. The gluteus maximus and the sartorius of males in their 30s composed 65%, while the rectus femoris and the tensor fasciae latae made up less than 60%. Lack of intensive body movement in their 30s resulted in a marked reduction of muscular CSA. Those in their 50s were shown to have 70-60% on the iliopsoas, pectinius and gluteus medius; those in their 70s, 60-50%. Slow reductions of whole muscle result in a decrease of step length, an expansion of the base support width, and inflexibility of the legs. For females, comparisons were made with those in their 30s. CSA of the rectus f emoris and pectinius showed a decrease in their 40s and values under 60% in their 70s, equal to the rates in males. Other muscles of females increased in their 40s, 50s and 60s and decreased in their 70s.
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