Proactive and reactive mechanisms play a role in stepping on inverting surfaces during gait
Proactive and reactive mechanisms play a role in stepping on inverting surfaces during gait
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DOI：
10.1152/jn.01226.2006
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发表时间：
2007-10-01
影响因子：
2.5
通讯作者：
Duysens, J.
中科院分区：
文献类型：
--
作者：
Nieuwenhuijzen, P. H. J. A.;Duysens, J.
在站立状态下，对踝关节内翻进行了广泛的研究。然而，倒置创伤发生在更动态的条件下，如行走。因此，在这项研究中，12名健康受试者在跑步机上行走时踩到了活板门，导致了脚踝突然内翻。首先，提出了10个对照试验(0度旋转)。然后，随机提出了20个刺激(25度旋转)和对照试验。肌电记录由六块小腿肌肉组成。所有肌肉的短潜伏期反应(SLR)约为40ms，晚潜伏期反应(LLR)约为90ms。在这两种反应中，腓肠肌的波幅最大。在功能上更重要、更大、更一致的LLR反应太晚了，无法抵抗在倒置过程中诱导的拉伸。这一反应的功能相关性必须在倒置之后。在第一次试验中，观察到LLR广泛的“惊吓”共激活。最近的试验表明，只有腓肠肌和腓肠肌(程度较小)的招募，这被视为从反应性控制向更主动的适应策略的转变。通过比较预期(但没有发生)反转的试验和受试者知道不会发生反转的试验，对这些主动策略进行了单独研究。在初次接触前胫骨前活动度降低，这与更加谨慎和稳定的足部放置相一致，这表明可能的内翻是预期的。此外，着陆后立即激活腓肠肌，以抵消即将到来的伸展。
Ankle inversions have been studied extensively during standing conditions. However, inversion traumas occur during more dynamic conditions, like walking. Therefore in this study sudden ankle inversions were elicited in 12 healthy subjects who stepped on a trap door while walking on a treadmill. First, 10 control trials (0 degrees of rotation) were presented. Then, 20 stimulus (25 degrees of rotation) and control trials were presented randomly. EMG recordings were made of six lower leg muscles. All muscles showed a short-latency response (SLR) of about 40 ms and a late-latency response (LLR) of about 90 ms. The peroneal muscles showed the largest amplitudes in both responses. The functionally more important, larger, and more consistent LLR response was too late to resist the induced stretch during the inversion. The functional relevance of this response must lie after the inversion. During the first trial a widespread "startle-like" coactivation of the LLR was observed. The last trials showed only a recruitment of the peroneal muscles and, to a lesser extent, the gastrocnemius lateralis, which is seen as a switch from reactive control to more proactive adaptive strategies. These proactive strategies were investigated separately by comparing trials in which inversion was expected ( but did not occur) with those in which subjects knew that no inversion would occur. Anticipation of a possible inversion was expressed in decreased tibialis anterior activity before initial contact, consistent with a more cautious and stable foot placement. Furthermore, immediately after landing, the peroneal muscles were activated to counteract the upcoming stretch.