PROTEIN, ENERGY AND EXERCISE EFFECTS ON SENESCENT MUSCLE

涉及离奇运动的运动，在老年人和年轻人之间有很大的不同。与年轻受试者相比，老年受试者经历了更多的肌肉损伤，更多的肌纤维蛋白分解，中性粒细胞减少和循环肌酸激酶活性。我们还证明，有规律的锻炼会增加对饮食蛋白质的需求，而饮食补充剂将有利于老年男性肌肉质量的增加。这项研究引导我们假设，在高强度PRT期间增加膳食蛋白质将增加肌肉蛋白质的合成，并增加肥大的速度。年龄较大的男性和女性将食用三个月的高热量饮食，提供0.8或1.6克的蛋白质RDA。因子氮平衡和持续的1-13C-亮氨酸输注将使我们能够检查全身氨基酸动力学和将标记结合到骨骼肌中，以确定饮食、年龄和PRT对肌肉蛋白质合成速度的影响。我们已经证明，计算机断层扫描和活检分析是检查肌肉肥厚率的非常敏感的工具。这些研究将是第一次在严格控制的代谢病房中检查饮食蛋白质对肌肉新陈代谢、大小和力量的影响。这项研究为研究老年人体内RDA蛋白的充分性以及训练对氮保持的影响提供了一个机会。这些研究将使我们能够在老年人开始和继续力量训练计划时为他们提出具体的营养建议。这项研究的PI已经离开了宾夕法尼亚州立大学，该协议已经关闭。在过去的一年里，肌肉核心实验室完成了几项测试。

Exercise that involves eccentric exercise, is quite different between old and young subjects. Compared to young, older subjects experience greater amounts of muscle damage, greater myofibillar protein breakdown, decreased neutrophilia and circulating creatine kinase activity. We have also demonstrated that regular exercise increases the need for dietary protein and a dietary supplement will favor the accretion of muscle mass in older men. This study leads us to the hypothesis that increased dietary protein during a high intensity PRT will increase muscle protein synthesisand increase the rate of hypertrophy. Older men and women will consume a eucaloric diet providing the protein RDA of 0.8 or 1.6g for three months. Factoral nitrogen balance along with constant, primed infusion of 1-13C-leucine will allow us to examine whole body amino acid kinetics and incorporation of the label into skeletal muscle to determine the effects of the diet, age, and PRT on the rate of muscle protein synthesis. We have shown that computerized tomography and biopsy analysis are very sensitive tools to examine the rate of muscle hypertrophy. These studies will be the first in which the effects of dietary protein on muscle metabolism, size and strength will be examined in a tightly controlled metabolic ward. This study provides an opportunity to examine the adequacy of the protein RDA in the elderly and the influence of training of N retention. These studies will allow us to make specific nutritional recommendations for the elderly as they initiate and continue with a strength training program. The PI for this study has left Penn State University and this protocol is closed. Several tests in the Muscle Core Lab were completed during the past year.