Russell Ian M, Wagner E V, Requejo P S, Mulroy S, Flashner H, McNitt-Gray J L
University of Southern California, United States.
University of Southern California, United States.
J Electromyogr Kinesiol. 2022 Feb;62:102340. doi: 10.1016/j.jelekin.2019.07.010. Epub 2019 Jul 30.
Understanding how individuals distribute mechanical demand imposed on their upper extremity during physically demanding activities provides meaningful insights to preserve function and mitigate detrimental mechanical loading of the shoulder. In this study, we hypothesized that parameterization of the shoulder net joint moment using four functional axes could characterize distribution tendencies about the shoulder during manual wheelchair propulsion and that regardless of demographics, a shoulder flexor dominant NJM distribution would be predominantly used by individuals with paraplegia (n = 130). Forces and kinematics of the upper extremity and trunk were quantified using motion capture and an instrumented wheel during steady state manual wheelchair propulsion at self-selected fast speeds on a stationary ergometer. The results indicate that parsing out the internal/external rotation component of the shoulder net joint moment about the upper arm and distributing the remainder across the three orthogonal axes of the torso was successful in identifying common shoulder net joint moment distribution techniques used across individuals with paraplegia during manual wheelchair propulsion. Distribution tendencies were predominantly flexor dominant across injury level, gender, time since injury, body mass index, and height demographics. The 4-axis parameterization of the shoulder NJM effectively differentiated moment distribution tendencies used by individuals during manual wheelchair propulsion using a functionally relevant representation of shoulder kinetics. Use of the four-axis parameterization of joint kinetics in future studies is expected to provide important insights that can advance knowledge, preserve function, and inform clinical decisions.
了解个体在体力要求较高的活动中如何分配施加在其上肢的机械需求，可为保护功能和减轻肩部有害机械负荷提供有意义的见解。在本研究中，我们假设使用四个功能轴对肩部净关节力矩进行参数化，可以表征手动轮椅推进过程中肩部的分布趋势，并且无论人口统计学特征如何，截瘫患者（n = 130）主要使用肩部屈肌主导的净关节力矩分布。在固定测力计上以自我选择的快速速度进行稳态手动轮椅推进时，使用运动捕捉和仪器化轮椅对上肢和躯干的力及运动学进行量化。结果表明，解析上臂周围肩部净关节力矩的内/外旋转分量，并将其余部分分布在躯干的三个正交轴上，成功识别了截瘫患者在手动轮椅推进过程中使用的常见肩部净关节力矩分布技术。在损伤水平、性别、受伤时间、体重指数和身高人口统计学特征方面，分布趋势主要以屈肌为主导。肩部净关节力矩的四轴参数化使用肩部动力学的功能相关表示，有效地区分了个体在手动轮椅推进过程中使用的力矩分布趋势。预计在未来研究中使用关节动力学的四轴参数化将提供重要见解，从而推动知识进步、保护功能并为临床决策提供依据。
