PROTEIN METABOLISM IN HEALTHY ELDERLY ADULTS

瘦体重和骨骼肌质量随着年龄的增长而下降。 尽管如此，总的来说，身体蛋白质代谢的参数 在60岁和60岁之间的年轻人和老年人中， 75岁时，数据表示为每单位瘦体重。 健康 老年人能够维持蛋白质氮平衡 摄入量与年轻成人的需求水平一致， 一般来说，健康的老年受试者可以恢复氮平衡， 时尚类似于年轻的成年人时，膳食蛋白质摄入量是 降低 蛋白质周转的特点是稳定 同位素标记的氨基酸和质谱。 当 校正瘦体重，全身蛋白质周转在健康 老年人与年轻人没有什么不同。 尽管如此，非肌肉组织的比例贡献， 全身蛋白质周转增加，因为部分肌肉 蛋白质合成率随年龄增长而下降。 的这种减少 然而，肌肉蛋白质的合成不仅仅是 老化本身，因为速率返回到一个年轻的成年人的价值时， 老化的肌肉对抗抵抗力。 此外，运动训练 改善老年人的肌肉质量和力量。 年龄依赖 生长激素分泌减少不太可能是 减少肌肉质量的老年人，因为有益的影响， 抗阻运动训练沿着对肌肉功能都没有增强 通过补充生长激素治疗。

Lean body mass and skeletal muscle mass decline with aging. Nonetheless, on the whole, the parameters of body protein metabolism are much the same in young and elder adults between the ages of 60 and 75 years when the data are expressed per unit lean mass. Healthy elderly adults are capable of maintaining nitrogen balance at protein intakes consistent with the young adult requirement level and, in general, healthy older subjects can reestablish nitrogen balance in a fashion similar to young adults when dietary protein intake is reduced. Protein turnover can be characterized with stable isotopically labeled amino acids and mass spectrometry. When corrected for lean mass, whole body protein turnover in healthy elderly adults is no different from that measured in younger adults. Nevertheless, the proportional contribution of non-muscle tissues to whole body protein turnover is increased since the fractional muscle protein synthesis rate declines with age. This reduction in muscle protein synthesis, however, is not simply a consequence of aging per se because the rate returns to a young adult value when aging muscles work against resistance. Further, exercise training improves muscle mass and strength in older adults. The age-dependent diminution in growth hormone secretion is not likely the cause of reduced muscle mass in the elderly since the beneficial effects of resistance exercise training along on muscle function are not enhanced by supplemental growth hormone treatment.