Schools of Rehabilitation Sciences and Human Kinetics, Faculty of Health Sciences, University of Ottawa, Ottawa, ON, Canada.
J Electromyogr Kinesiol. 2011 Jun;21(3):471-7. doi: 10.1016/j.jelekin.2011.02.001. Epub 2011 Mar 4.
Ankle muscle activity is important in regulating postural control as well as more complex movement tasks. Fatigue of these muscles clearly influences postural stability; however, the mechanisms responsible for this change have not been well characterized. In this study the fatigue produced in the plantar (PF) and dorsiflexors (DF) during intermittent, isometric contractions was examined and the recovery process was monitored for ten minutes post-fatigue. Fifteen healthy participants alternated between isometric PF and DF contractions until the torque was reduced to >50% of the pre-fatigue maximal voluntary contraction level in both directions. Peripheral fatigue was identified by measuring the change in the twitch torque and M-wave amplitude pre and post-fatigue. Central fatigue was determined by comparing the level of voluntary activation in the PF and DF between pre and post-fatigue. The fatigue protocol decreased the torque production in PF and DF to similar levels; however, the characteristics and recovery of the fatigue were different for the two muscle groups. This study demonstrates that although the torque produced by two antagonist muscles can be reduced to the same level, the mechanisms responsible for this change may not be similar and therefore may not impact motor tasks in the same way.
踝关节肌肉活动对于调节姿势控制以及更复杂的运动任务都很重要。这些肌肉的疲劳显然会影响姿势稳定性；然而，导致这种变化的机制尚未得到很好的描述。在这项研究中，研究了间歇性等长收缩过程中足底（PF）和背屈肌（DF）的疲劳，并在疲劳后十分钟内监测恢复过程。15 名健康参与者交替进行等长 PF 和 DF 收缩，直到两个方向的扭矩都降低到预疲劳最大自主收缩水平的 >50%。通过测量疲劳前后的抽搐扭矩和 M 波幅度来确定外周疲劳。通过比较疲劳前后 PF 和 DF 的自愿激活水平来确定中枢疲劳。疲劳方案使 PF 和 DF 的扭矩产生降低到相似水平；然而，两组肌肉的疲劳特征和恢复方式不同。本研究表明，尽管两种拮抗肌产生的扭矩可以降低到相同水平，但导致这种变化的机制可能不同，因此可能不会以相同的方式影响运动任务。
