PROTEIN, ENERGY AND EXERCISE EFFECTS ON SENESCENT MUSCLE

涉及古怪运动的运动在老年人和年轻人之间有很大的不同。与年轻人相比，老年受试者经历更大程度的肌肉损伤，更大程度的肌纤维蛋白分解，中性粒细胞减少和循环肌酸激酶活性降低。我们还证明，定期运动增加了对膳食蛋白质的需求，膳食补充剂有利于老年男性肌肉质量的增加。这项研究使我们得出这样的假设，即在高强度PRT期间增加饮食蛋白质会增加肌肉蛋白质合成并增加肥厚的速度。年龄较大的男性和女性将在三个月的时间里食用提供0.8或1.6克蛋白质RDA的高热量饮食。因子氮平衡以及1- 13c -亮氨酸的持续注入将使我们能够检查全身氨基酸动力学，并将标签纳入骨骼肌，以确定饮食，年龄和PRT对肌肉蛋白质合成速率的影响。我们已经表明，计算机断层扫描和活检分析是非常敏感的工具来检查肌肉肥大率。这些研究将是第一次在严格控制的代谢病房中检查膳食蛋白质对肌肉代谢、大小和力量的影响。本研究为研究老年人蛋白质RDA的充分性以及训练对氮潴留的影响提供了机会。这些研究将使我们能够为老年人提出具体的营养建议，因为他们开始并继续进行力量训练计划。本研究的PI已离开宾夕法尼亚州立大学，本协议截止。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.