Loenneke Jeremy P, Wilson Jacob M, Balapur Abhishek, Thrower Austin D, Barnes Jeremy T, Pujol Thomas J
Department of Health and Exercise Science, University of Oklahoma, Norman, OK 73019-0615, USA.
Clin Physiol Funct Imaging. 2012 Jul;32(4):268-73. doi: 10.1111/j.1475-097X.2012.01121.x. Epub 2012 Jan 18.
Exercise to failure results in similar muscle protein synthesis responses, independent of intensity. However, low-intensity exercise likely requires more time under tension and those with injuries may be incapable of sustaining the mechanical stress to reach failure.
The purpose was to determine whether elastic knee wraps (KW) provide a stimulus to decrease time under tension and overall volume of work while maintaining a similar level of metabolic stress.
Thirteen healthy subjects participated in a randomized crossover study consisting of three trials. The first determined 1 repetition maximum (1RM) on the bilateral leg extension. Subjects were then assigned to a blood flow restriction (BFR) or control (CON) group. After trial 2, subjects crossed over to the opposite trial. KW were placed around the thigh of each leg during BFR. Leg extensions were completed at 30% 1RM until failure. Whole blood lactate (WBL) was taken pre-, post-, and 3 and 5 min postexercise. Heart rate (HR) was measured before, following the first and second sets, and 3 and 5 min postexercise.
This study found KW provide a BFR stimulus allowing failure to occur sooner with similar metabolic stress postreperfusion. There were no differences in HR at any time point.
These results may benefit populations that cannot sustain the mechanical stress of high-intensity exercise or low-intensity exercise that requires a longer sustained time under tension.
运动至力竭会导致相似的肌肉蛋白质合成反应，与强度无关。然而，低强度运动可能需要更长的张力作用时间，且受伤者可能无法承受达到力竭所需的机械应力。
目的是确定弹性护膝（KW）是否能在维持相似代谢应激水平的同时，提供一种刺激以减少张力作用时间和总工作量。
13名健康受试者参与了一项包含三项试验的随机交叉研究。第一项试验测定双侧腿部伸展的1次重复最大值（1RM）。然后将受试者分为血流限制（BFR）组或对照组（CON）。在试验2之后，受试者交叉至相反的试验组。在BFR期间，KW缠绕在每条腿的大腿上。腿部伸展以30%1RM的强度进行，直至力竭。在运动前、运动后、运动后3分钟和5分钟采集全血乳酸（WBL）。在运动前、第一组和第二组运动后以及运动后3分钟和5分钟测量心率（HR）。
本研究发现KW提供了一种BFR刺激，使得在再灌注后具有相似代谢应激的情况下能更快出现力竭。在任何时间点，HR均无差异。
这些结果可能对无法承受高强度运动机械应力或需要更长持续张力作用时间的低强度运动的人群有益。
