Hill Christopher M, DeBusk Hunter, Simpson Jeffrey D, Miller Brandon L, Knight Adam C, Garner John C, Wade Chip, Chander Harish
Northern Illinois University, Department of Kinesiology and Physical Education, Dekalb, IL, United States.
Mississippi State University, Department of Industrial and System Engineering, Mississippi State, MS, United States.
Saf Health Work. 2019 Sep;10(3):321-326. doi: 10.1016/j.shaw.2019.06.002. Epub 2019 Jun 12.
Performing cognitive tasks and muscular fatigue have been shown to increase muscle activity of the lower extremity during quiet standing. A common intervention to reduce muscular fatigue is to provide a softer shoe-surface interface. However, little is known regarding how muscle activity is affected by softer shoe-surface interfaces during static standing. The purpose of this study was to assess lower extremity muscular activity during erect standing on three different standing surfaces, before and after an acute workload and during cognitive tasks.
Surface electromyography was collected on ankle dorsiflexors and plantarflexors, and knee flexors and extensors of fifteen male participants. Dependent electromyography variables of mean, peak, root mean square, and cocontraction index were calculated and analyzed with a 2 × 2 × 3 within-subject repeated measures analysis of variance.
Pre-workload muscle activity did not differ between surfaces and cognitive task conditions. However, greater muscle activity during post-workload balance assessment was found, specifically during the cognitive task. Cognitive task errors did not differ between surface and workload.
The cognitive task after workload increased lower extremity muscular activity compared to quite standing, irrespective of the surface condition, suggesting an increased demand was placed on the postural control system as the result of both fatigue and cognitive task.
研究表明，在安静站立时执行认知任务和出现肌肉疲劳会增加下肢的肌肉活动。一种常见的减轻肌肉疲劳的干预措施是提供更柔软的鞋底与地面接触界面。然而，关于在静态站立时更柔软的鞋底与地面接触界面如何影响肌肉活动，人们知之甚少。本研究的目的是评估在三种不同站立表面上直立站立时、急性负荷前后以及认知任务期间的下肢肌肉活动。
收集了15名男性参与者的踝背屈肌、跖屈肌以及膝屈肌和伸肌的表面肌电图。计算并分析了平均、峰值、均方根和共同收缩指数等肌电图相关变量，并采用2×2×3受试者内重复测量方差分析。
负荷前的肌肉活动在不同表面和认知任务条件下并无差异。然而，发现在负荷后平衡评估期间，尤其是在认知任务期间，肌肉活动更为强烈。不同表面和负荷条件下的认知任务错误并无差异。
负荷后的认知任务与安静站立相比，增加了下肢肌肉活动，与表面条件无关，这表明疲劳和认知任务共同导致了对姿势控制系统的需求增加。
