Department of Biomedical Sciences for Health (SCIBIS), Università degli Studi di Milano, Milan, ITALY.
Med Sci Sports Exerc. 2021 Oct 1;53(10):2066-2075. doi: 10.1249/MSS.0000000000002677.
The current study investigated the effects of unilateral passive stretching on the neuromuscular mechanisms involved in the force-generating capacity of the contralateral muscle.
Twenty-six healthy men underwent unilateral passive stretching of the plantarflexors (5 × 45 s on + 15 s off; total stretching time, 225 s). Before and after the stretching protocol, contralateral ankle range of motion, maximum voluntary contraction (MVC) of the plantarflexors, and surface electromyographic root-mean-square (sEMG RMS) of the soleus and the gastrocnemii muscles were determined. Concurrently, V-wave, maximum and superimposed H-reflex, and M-wave were elicited via nerve stimulation to estimate the supraspinal, spinal, and peripheral mechanisms, respectively. sEMG RMS, V-wave, and H-reflex were normalized to the M-wave.
After passive stretching, contralateral ankle range of motion was increased (+8% [1%/15%], effect size [ES] = 0.43 [0.02/0.84], P < 0.001), MVC of the plantarflexors was decreased (-9% [-21%/-2%], ES = -0.96 [-1.53/-0.38], P < 0.001), and the sEMG RMS/M-wave of the soleus and the gastrocnemii muscles was decreased (≈-9%, ES ≈ -0.33, P < 0.05). Concurrently, the V-wave/M-wave superimposed was decreased in all muscles (≈-13%, ES = -0.81 to -0.52, P < 0.05). No change in H-reflex/M-wave and M-wave was observed under both maximum and superimposed condition. The decrease in the MVC and the sEMG RMS of the contralateral muscle was accompanied by a decrease in the V-wave/M-wave but not the H-reflex/M-wave ratios and the M-wave.
The present outcomes suggest that only supraspinal mechanisms might be involved in the contralateral decrease in the maximum force-generating capacity.
本研究旨在探讨单侧被动伸展对参与对侧肌肉产生力量的神经肌肉机制的影响。
26 名健康男性接受了足底屈肌的单侧被动伸展（5×45 秒+15 秒休息；总伸展时间 225 秒）。在伸展方案前后，测定对侧踝关节活动范围、足底屈肌的最大自主收缩（MVC）以及比目鱼肌和腓肠肌的表面肌电图均方根（sEMG RMS）。同时，通过神经刺激引出 V 波、最大和叠加 H 反射以及 M 波，分别估计中枢神经系统、脊髓和周围机制。将 sEMG RMS、V 波和 H 反射归一化为 M 波。
被动伸展后，对侧踝关节活动范围增加（+8%[1%/15%]，效应量[ES]=0.43[0.02/0.84]，P<0.001），足底屈肌的 MVC 降低（-9%[-21%/-2%]，ES=-0.96[-1.53/-0.38]，P<0.001），比目鱼肌和腓肠肌的 sEMG RMS/M 波降低（约-9%，ES≈-0.33，P<0.05）。同时，所有肌肉的 V 波/M 波叠加均降低（约-13%，ES=-0.81 至-0.52，P<0.05）。在最大和叠加条件下，H 反射/M 波和 M 波均无变化。对侧肌肉 MVC 和 sEMG RMS 的降低伴随着 V 波/M 波的降低，但 H 反射/M 波比值和 M 波没有变化。
本研究结果表明，只有中枢神经系统机制可能参与对侧最大力量产生能力的降低。
