Muscle activation strategies at the knee during running and cutting maneuvers
Muscle activation strategies at the knee during running and cutting maneuvers
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DOI：
10.1097/00005768-200301000-00019
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发表时间：
2003-01-01
期刊：
影响因子：
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通讯作者：
Ackland, TR
中科院分区：
文献类型：
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作者：
Besier, TF;Lloyd, DG;Ackland, TR
目的：本文的目的是调查在预先计划（PP）和意外（UN）的运行和切割任务，相对于施加到关节的外部力矩的膝关节周围的肌肉的激活模式。据推测，PP任务期间的激活策略将对应于施加到膝关节的外部负荷的大小和方向，PP和UN任务之间的肌肉激活模式将有所不同。方法：11名健康男性受试者在PP和UN条件下进行一系列跑步和切割任务。从10个膝关节肌肉的激活，确定使用全波整流，滤波，并在接触前阶段和两个时期的立场阶段计算的标准化EMG。膝关节屈伸肌群比例指示了共同收缩的水平。根据肌肉对抗外部施加的内翻/外翻和内/外旋关节载荷的能力，将肌肉分为内/外旋和内/外旋肌肉组。结果如下：选择性激活内侧/外侧和内/外旋肌肉和共同收缩的屈肌和伸肌被用来稳定关节PP条件下，而广义的共同收缩策略，采用在UN条件。UN回避任务期间的净肌肉激活增加了10- 20%，而施加的内翻/外翻和内/外旋关节力矩增加了约100%。结论：在PP条件下，激活模式似乎被选择来支持膝关节处经历的外部负荷，例如，激活内侧肌肉以抵抗施加的外翻力矩。在UN条件下，没有选择性激活肌肉来对抗外部膝关节负荷，所采用的激活模式是广义共同收缩。这些发现对非接触性膝关节韧带损伤的病因学有一定的意义。
Purpose: The purpose of this article was to investigate the activation patterns of muscles surrounding the knee during preplanned (PP) and unanticipated (UN) running and cutting tasks, with respect to the external moments applied to the joint. It was hypothesized that activation strategies during PP tasks would correspond to the magnitude and direction of the external loads applied to the knee joint, and the muscle activation patterns would differ between PP and UN tasks. Methods: Eleven healthy male subjects performed a series of running and cutting tasks under PP and UN conditions. Activation from 10 knee muscles were determined using full-wave rectified, filtered, and normalized EMG calculated during a precontact phase and two epochs across the stance phase. Knee joint flexor and extensor muscle group ratios indicated the level of co-contraction. Individual muscles were also grouped into medial/lateral and internal/external rotation muscle groups, based upon their ability to counter externally applied varus/valgus and internal/external rotation joint loads, respectively. Results: Selective activation of medial/lateral and internal/external rotation muscles and co-contraction of flexors and extensors were used to stabilize the joint under PP conditions, whereas generalized co-contraction strategies were employed during the UN condition. Net muscle activation during the UN sidestepping tasks increased by 10-20%, compared with an approximately 100% increase in applied varus/valgus and internal/ external rotation joint moments. Conclusion: In PP conditions, activation patterns appear to be selected to support the external loads experienced at the knee, e.g., medial muscles activated to resist applied valgus moments. Under UN conditions, there was no selective activation of muscles to counter the external knee load, with generalized co-contraction being the activation pattern adopted. These findings have implications for the etiology of noncontact knee ligament injuries.