Neuromuscular control in landing from supra-maximal dropping height
Neuromuscular control in landing from supra-maximal dropping height
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DOI：
10.1152/japplphysiol.90776.2008
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发表时间：
2009-02-01
影响因子：
3.3
通讯作者：
Nicol, C.
中科院分区：
文献类型：
--
作者：
Galindo, A.;Barthelemy, J.;Nicol, C.
马晓东，马晓东，马晓东，马晓东，马晓东，马晓东，马晓东，马晓东。中国生物医学工程学报（英文版），2009。首次发表于2008年12月4日；doi: 10.1152 / japplphysiol.90776.2008。-本研究利用高冲击力的超最大值着陆来检查冲击力前水平对冲击力后肌电图（EMG）活动的影响，特别是对短潜伏期肌电反射（SLR）成分的影响。单侧腿着地是在坐着的位置上进行的，从高处释放后，但单独恒定的下降高度。固定在雪橇座位前部的下肢引导装置允许受试者维持给定的预设力水平直至撞击。这个力水平可以自由选择，也可以设定为最大等距跖屈力的20%、35%和50%。记录下肢8块主要肌肉的肌电活动。预期撞击前力水平的增加将需要在撞击后阶段进行保护性神经策略的干预，从而减弱SLR振幅。超声记录证实比目鱼肌束被拉伸以诱发单反。主要发现是所有测试条件下的冲击峰值力和冲击后肌电图活动（包括SLR响应）的相似性。这两种观测结果主要归因于相似的肌电图水平和接近撞击的力水平。当接近撞击时，保持给定的预设力量水平的指令确实被推翻了。这表明，在目前的超最大着陆条件下，一个保护性的中枢神经策略确实发生了，该策略考虑了预先设定的力水平，以确保类似的冲击载荷。
Galindo A, Barthelemy J, Ishikawa M, Chavet P, Martin V, Avela J, Komi PV, Nicol C. Neuromuscular control in landing from supramaximal dropping height. J Appl Physiol 106: 539-547, 2009. First published December 4, 2008; doi: 10.1152/japplphysiol.90776.2008.-The present study utilized high-impact supra-maximal landings to examine the influence of the pre-impact force level on the post-impact electromyographic (EMG) activity and, in particular, on the short latency EMG reflex (SLR) component. Unilateral-leg landings were performed in a sitting position on a sledge apparatus after release from high, but individually constant dropping height. A lower limb guiding device fixed to the front of the sledge seat allowed the subjects to sustain a given pre-set force level up to impact. This force level was either freely chosen or set at 20, 35, and 50% of maximal isometric plantarflexion force. EMG activity was recorded from eight major lower limb muscles. It was expected that the increase in the pre-impact force level would require the intervention of a protective neural strategy during the post-impact phase that would attenuate the SLR amplitude. The ultrasonography recordings confirmed that the soleus fascicles were stretched to induce SLR. The main finding was the similarity across all tested conditions of the impact peak force and post-impact EMG activity, including the SLR response. Both observations are mostly attributed to the similar EMG levels and close force levels reached toward impact. The instruction to maintain a given pre-set force level was indeed overruled when getting close to impact. It is suggested that, in the present supra-maximal landing condition, a protective central neural strategy did occur that took into account the pre-set force level to secure similar impact loads.