Department of Human Health and Nutritional Sciences, College of Biological Sciences, University of Guelph, Guelph Ontario, Canada.
J Strength Cond Res. 2020 Nov;34(11):3139-3148. doi: 10.1519/JSC.0000000000003815.
Caron, KE, Burr, JF, and Power, GA.. The effect of a stretch-shortening cycle on muscle activation and muscle oxygen consumption: a study of history-dependence. J Strength Cond Res 34(11): 3139-3148, 2020-Stretch-shortening cycles (SSCs) are observed in a variety of human movements and are associated with increases in performance. Few studies have considered the effects of stretch-induced residual force enhancement (rFE) and shortening-induced residual force depression (rFD) during an SSC, and none have considered these properties during voluntary contractions. With force matched via a robotically resisted Smith machine, we hypothesized that in the isometric steady-state following an SSC (a) muscle activation (electromyography) of the knee and hip extensors would be greater and (b) muscle oxygen consumption be higher than the reference isometric condition (ISO), but less than the rFD condition. Subjects (n = 20, male, 24.9 ± 3.9 year) performed a squat exercise over 100-140° knee angle and a matched ISO at the top and bottom of the squat. After active shortening, the vastus medialis (VM), vastus lateralis (VL), and gluteus maximus (GM) showed activation increase in the rFD-state compared with ISO (∼15%, ∼11%, and ∼25% respectively). During the isometric steady-state following the SSC, there was no difference in activation as compared with ISO for VM, VL, but GM showed an activation increase of ∼15%. VM and VL showed an activation increase in the rFD-state compared with the isometric steady-state following SSC (∼16 and ∼10% respectively). Muscle oxygen consumption (tissue saturation index) was not different during the isometric steady-states following rFD and SSC compared with ISO. During a voluntary SSC exercise, the activation increase expected in the FD-state was attenuated, with no change in muscle oxygen consumption. The concomitant role of rFE and rFD during a voluntary position-matched SSC seems to counteract shortening-induced activation increase and may optimize movement economy.
卡隆，KE，伯尔，JF 和鲍尔，GA。伸展-缩短周期对肌肉激活和肌肉耗氧量的影响：历史依赖性研究。J 力量与调节研究 34（11）：3139-3148，2020-伸展-缩短周期（SSC）在各种人体运动中都有观察到，并且与性能提高有关。很少有研究考虑在 SSC 期间伸展引起的残余力增强（rFE）和缩短引起的残余力抑制（rFD）的影响，也没有研究在自愿收缩期间考虑这些特性。通过机器人抵抗史密斯机器进行力匹配，我们假设在 SSC 之后的等长稳态期间（a）膝关节和髋关节伸展肌的肌肉激活（肌电图）会更大，（b）肌肉耗氧量会高于参考等长条件（ISO），但低于 rFD 条件。受试者（n=20，男性，24.9±3.9 岁）在 100-140°膝关节角度下进行深蹲运动，并在深蹲的顶部和底部进行匹配的 ISO。在主动缩短后，股直肌（VM）、股外侧肌（VL）和臀大肌（GM）在 rFD 状态下的激活增加与 ISO 相比（分别约为 15%、11%和 25%）。在 SSC 之后的等长稳态期间，VM、VL 与 ISO 相比，激活没有差异，但 GM 显示激活增加约 15%。VM 和 VL 在 rFD 状态下的激活增加与 SSC 后的等长稳态相比（分别约为 16%和 10%）。与 ISO 相比，rFD 和 SSC 后的等长稳态期间肌肉耗氧量（组织饱和度指数）没有差异。在自愿 SSC 运动期间，FD 状态下预期的激活增加被减弱，肌肉耗氧量没有变化。在自愿位置匹配的 SSC 期间，rFE 和 rFD 的共同作用似乎抵消了缩短引起的激活增加，并可能优化运动经济性。
