Fry Christopher S, Glynn Erin L, Drummond Micah J, Timmerman Kyle L, Fujita Satoshi, Abe Takashi, Dhanani Shaheen, Volpi Elena, Rasmussen Blake B
University of Texas Medical Branch, Sealy Center on Aging, Department of Physical Therapy, Division of Rehabilitation Sciences, 301 Univ. Blvd., Galveston, TX 77555-1144, USA.
J Appl Physiol (1985). 2010 May;108(5):1199-209. doi: 10.1152/japplphysiol.01266.2009. Epub 2010 Feb 11.
The loss of skeletal muscle mass during aging, sarcopenia, increases the risk for falls and dependence. Resistance exercise (RE) is an effective rehabilitation technique that can improve muscle mass and strength; however, older individuals are resistant to the stimulation of muscle protein synthesis (MPS) with traditional high-intensity RE. Recently, a novel rehabilitation exercise method, low-intensity RE, combined with blood flow restriction (BFR), has been shown to stimulate mammalian target of rapamycin complex 1 (mTORC1) signaling and MPS in young men. We hypothesized that low-intensity RE with BFR would be able to activate mTORC1 signaling and stimulate MPS in older men. We measured MPS and mTORC1-associated signaling proteins in seven older men (age 70+/-2 yr) before and after exercise. Subjects were studied identically on two occasions: during BFR exercise [bilateral leg extension exercise at 20% of 1-repetition maximum (1-RM) with pressure cuff placed proximally on both thighs and inflated at 200 mmHg] and during exercise without the pressure cuff (Ctrl). MPS and phosphorylation of signaling proteins were determined on successive muscle biopsies by stable isotopic techniques and immunoblotting, respectively. MPS increased 56% from baseline after BFR exercise (P<0.05), while no change was observed in the Ctrl group (P>0.05). Downstream of mTORC1, ribosomal S6 kinase 1 (S6K1) phosphorylation and ribosomal protein S6 (rpS6) phosphorylation increased only in the BFR group after exercise (P<0.05). We conclude that low-intensity RE in combination with BFR enhances mTORC1 signaling and MPS in older men. BFR exercise is a novel intervention that may enhance muscle rehabilitation to counteract sarcopenia.
衰老过程中骨骼肌质量的丧失，即肌肉减少症，会增加跌倒和依赖的风险。抗阻运动（RE）是一种有效的康复技术，可以改善肌肉质量和力量；然而，老年人对传统高强度抗阻运动刺激肌肉蛋白合成（MPS）具有抗性。最近，一种新型的康复运动方法，即低强度抗阻运动结合血流限制（BFR），已被证明可刺激年轻男性的雷帕霉素复合物1（mTORC1）信号传导和肌肉蛋白合成。我们假设低强度抗阻运动结合血流限制能够激活老年男性的mTORC1信号传导并刺激肌肉蛋白合成。我们在7名老年男性（年龄70±2岁）运动前后测量了肌肉蛋白合成和mTORC1相关信号蛋白。在两种情况下对受试者进行相同的研究：在血流限制运动期间[双侧腿部伸展运动，强度为1次重复最大值（1-RM）的20%，压力袖带近端放置在双侧大腿上并充气至200 mmHg]以及在无压力袖带的运动期间（对照）。分别通过稳定同位素技术和免疫印迹法在连续的肌肉活检样本上测定肌肉蛋白合成和信号蛋白的磷酸化。血流限制运动后，肌肉蛋白合成较基线增加了56%（P<0.05），而对照组未观察到变化（P>0.05）。在mTORC1的下游，运动后仅血流限制组的核糖体S6激酶1（S6K1）磷酸化和核糖体蛋白S6（rpS6）磷酸化增加（P<0.05）。我们得出结论，低强度抗阻运动结合血流限制可增强老年男性的mTORC1信号传导和肌肉蛋白合成。血流限制运动是一种新型干预措施，可能会增强肌肉康复以对抗肌肉减少症。
