Monjo Florian, Forestier Nicolas
Laboratoire Interuniversitaire de Biologie de la Motricité (EA 7424), UFR-SceM/STAPS/Université Savoie Mont-Blanc, 73376 Le Bourget du Lac, France.
Laboratoire Interuniversitaire de Biologie de la Motricité (EA 7424), UFR-SceM/STAPS/Université Savoie Mont-Blanc, 73376 Le Bourget du Lac, France.
Hum Mov Sci. 2017 Aug;54:1-12. doi: 10.1016/j.humov.2017.03.001. Epub 2017 Mar 18.
We investigated whether and how the movement initiation condition (IC) encountered during the early movements performed following focal muscle fatigue affects the postural control of discrete ballistic movements. For this purpose, subjects performed shoulder flexions in a standing posture at maximal velocity under two movement IC, i.e., in self-paced conditions and submitted to a Stroop-like task in which participants had to trigger fast shoulder flexions at the presentation of incongruent colors. Shoulder flexion kinematics, surface muscle activity of focal and postural muscles as well as center-of-pressure kinematics were recorded. The initial IC and the order in which subjects were submitted to these two conditions were varied within two separate experimental sessions. IC schedule was repeated before and after fatigue protocols involving shoulder flexors. The aim of this fatigue procedure was to affect acceleration-generating capacities of focal muscles. In such conditions, the postural muscle activity preceding and accompanying movement execution is expected to decrease. Following fatigue, when subjects initially moved in self-paced conditions, postural muscle activity decreased and scaled to the lower focal peak acceleration. This postural strategy then transferred to the Stroop-like task. In contrast, when subjects initially moved submitted to the Stroop-like task, postural muscle activity did not decrease and this transferred to self-paced movements. Regarding the center-of-pressure peak velocity, which is indicative of the efficiency of the postural actions generated in stabilizing posture, no difference appeared between the two sessions post-fatigue. This highlights an optimization of the postural actions when subjects first moved in self-paced conditions, smaller postural muscle activation levels resulting in similar postural consequences. In conclusion, the level of neuromuscular activity associated with the postural control is affected and can be optimized by the initial movement IC experienced post-fatigue. Beyond the fundamental contributions arising from these results, we point out potential applications for trainers and sports instructors.
我们研究了在局灶性肌肉疲劳后早期运动中遇到的运动起始条件（IC）是否以及如何影响离散弹道运动的姿势控制。为此，受试者在站立姿势下以最大速度进行肩部屈曲，有两种运动起始条件，即在自定节奏条件下以及接受类似斯特鲁普任务，即参与者必须在出现不一致颜色时触发快速肩部屈曲。记录了肩部屈曲运动学、局灶性和姿势性肌肉的表面肌电活动以及压力中心运动学。在两个单独的实验环节中，改变了初始起始条件以及受试者接受这两种条件的顺序。在涉及肩部屈肌的疲劳方案前后重复起始条件安排。该疲劳程序的目的是影响局灶性肌肉产生加速度的能力。在这种情况下，预计运动执行之前和伴随运动执行的姿势性肌肉活动会减少。疲劳后，当受试者最初在自定节奏条件下运动时，姿势性肌肉活动减少并与较低的局灶性峰值加速度成比例。然后这种姿势策略转移到类似斯特鲁普任务中。相反，当受试者最初在类似斯特鲁普任务下运动时，姿势性肌肉活动没有减少，并且这种情况转移到自定节奏运动中。关于压力中心峰值速度，它表明在稳定姿势时产生的姿势动作的效率，疲劳后两个环节之间没有差异。这突出了受试者最初在自定节奏条件下运动时姿势动作的优化，较小的姿势性肌肉激活水平导致类似的姿势结果。总之，与姿势控制相关的神经肌肉活动水平会受到影响，并且可以通过疲劳后经历的初始运动起始条件进行优化。除了这些结果产生的基本贡献外，我们还指出了对教练和体育指导员的潜在应用。
