Department of Physical Therapy, Tehran University of Medical Sciences, Pich-e-Shemiran, Enghelab Avenue, Tehran, Iran.
Spine (Phila Pa 1976). 2010 May 15;35(11):E443-51. doi: 10.1097/BRS.0b013e3181bc34b5.
An experimental design to investigate activation patterns of trunk muscles during multidirectional exertions.
To evaluate trunk muscle activation patterns in varying directions and moment magnitudes during an isometric task, and to investigate the effects of angle and level of isometric exertion on the electromyography (EMG) variability of trunk muscles in upright posture.
Few studies have investigated trunk muscle activation patterns in multidirectional exertions with different moment magnitudes.
A total of 12 asymptomatic male subjects were participated in the study. The EMG activity of 10 selected trunk muscles was collected in the 3 seconds end point matching tasks in 8 angles and 3 magnitudes of exertion. Trunk muscle activation patterns were examined using EMG tuning curves and measuring preferred direction (mean vector direction) and the index of spatial focus. The effect of exertion level on these measures was investigated by Rao test. The effects of angle and level of exertion on the EMG variability of trunk muscles were tested by analysis of variance with repeated measures design.
No significant difference in EMG tuning curves, preferred direction, and the index of spatial focus was found for each muscle studied across exertion levels (P > 0.05). The index of spatial focus of most muscles studied was not changed with increasing moment magnitude. EMG variability of trunk muscles was significantly affected by angle and level of exertion and their interaction effect (P < 0.001).
Consistent activation patterns of trunk muscles were found within and among subjects in different moment magnitudes. The index of spatial focus indicated that probably no shift to a higher co-contraction strategy has been adapted with increasing moment magnitude. The results suggested that increased EMG variability of trunk muscles in asymmetric exertions may be associated with lower trunk controllability during combined exertions.
一项旨在研究躯干肌肉在多向用力时激活模式的实验设计。
评估等长任务中不同方向和力矩大小下躯干肌肉的激活模式，并研究在直立姿势下，角度和等长用力水平对躯干肌肉肌电图（EMG）变异性的影响。
很少有研究调查过在不同力矩大小的多向用力中躯干肌肉的激活模式。
本研究共纳入 12 名无症状男性受试者。在 8 个角度和 3 个施力大小的 3 秒端点匹配任务中，采集了 10 块选定躯干肌肉的 EMG 活动。使用 EMG 调谐曲线和测量最佳方向（平均向量方向）和空间焦点指数来检查躯干肌肉的激活模式。通过 Rao 检验研究用力水平对这些措施的影响。通过重复测量设计的方差分析，测试角度和用力水平对躯干肌肉 EMG 变异性的影响。
在不同用力水平下，研究的每块肌肉的 EMG 调谐曲线、最佳方向和空间焦点指数均无显著差异（P > 0.05）。研究的大多数肌肉的空间焦点指数随力矩的增加而不变。躯干肌肉的 EMG 变异性受角度和用力水平及其相互作用的影响显著（P < 0.001）。
在不同力矩大小下，受试者内在和之间的躯干肌肉激活模式一致。空间焦点指数表明，随着力矩的增加，可能没有转向更高的协同收缩策略。研究结果表明，不对称用力时躯干肌肉的 EMG 变异性增加可能与联合用力时躯干的可控性降低有关。
