Phillips David, Kosek Peter, Karduna Andrew
Department of Exercise Science and Physical Education, Montclair State University, 1 Normal Avenue, Montclair, NJ 07043, United States.
Oregon Neurosurgery, 3355 Riverbend Drive, Suite 400, Springfield, OR 97477, United States.
J Biomech. 2018 Feb 8;68:65-69. doi: 10.1016/j.jbiomech.2017.12.015. Epub 2017 Dec 15.
During maximum effort, the supraspinatus muscle contributes approximately 50% of the torque need to elevate the arm, but this has not been examined at sub-maximal levels. The purpose of this study was to determine the contribution of the supraspinatus muscle to shoulder elevation at sub-maximal levels. Seven healthy subjects (four males, three females) performed isometric ramp contractions at the shoulder. Middle deltoid electromyography (EMG) and force applied at the wrist were collected before and after a suprascapular nerve block. For the same level of deltoid EMG, less external force will be measured after the nerve block as the supraspinatus muscle no longer contributes. The difference between the EMG/force curve was the contribution of the supraspinatus muscle. The supraspinatus contributed 40%, 95% CI [32%-48%], to shoulder elevation. The effect of angle (p = .67) and % maximal voluntary contraction (p = .13) on supraspinatus contribution were not significant. The maximum is slightly less than reported in a previous suprascapular nerve block study using maximal contractions. The results from this study can be used to assess supraspinatus contribution in rotator cuff tears, after rehabilitation interventions, and as a restraint in computation modelling.
在最大用力时，冈上肌对抬高手臂所需扭矩的贡献约为50%，但在次最大用力水平下尚未对此进行研究。本研究的目的是确定冈上肌在次最大用力水平下对肩部抬高的贡献。七名健康受试者（四名男性，三名女性）在肩部进行等长斜坡收缩。在肩胛上神经阻滞前后收集三角肌中部肌电图（EMG）和施加在手腕上的力。对于相同水平的三角肌EMG，神经阻滞后测量到的外力会减少，因为冈上肌不再起作用。EMG/力曲线之间的差异就是冈上肌的贡献。冈上肌对肩部抬高的贡献为40%，95%置信区间[32%-48%]。角度（p = 0.67）和最大自主收缩百分比（p = 0.13）对冈上肌贡献的影响不显著。该最大值略低于先前一项使用最大收缩的肩胛上神经阻滞研究中的报告值。本研究结果可用于评估肩袖撕裂、康复干预后冈上肌的贡献，并作为计算模型中的一种约束条件。
