Boninger M L, Cooper R A, Robertson R N, Shimada S D
Department of Orthopaedic Surgery, University of Pittsburgh Medical Center and Highland Drive VA Medical Center, Pennsylvania 15213, USA.
Am J Phys Med Rehabil. 1997 Sep-Oct;76(5):420-6. doi: 10.1097/00002060-199709000-00013.
Upper limb pain frequently occurs in manual wheelchair users. Analyzing the pushrim forces and hub moments occurring during wheelchair propulsion is a first step in gaining insight into the cause of this pain. The objectives of this study were as follows: to describe the forces and moments occurring during wheelchair propulsion; to obtain variables that characterize pushrim forces and are statistically stable; and to determine how these variables change with speed. Convenience samples (n = 6) of paralympic athletes who use manual wheelchairs for mobility and have unimpaired arm function were tested. Each subject propelled a standard wheelchair on a dynamometer at 1.3 and 2.2 m/s. Biomechanical data were obtained using a force- and moment-sensing pushrim and a motion analysis system. A number of variables that describe the force and moment curves were evaluated for stability using Cronbach's alpha. Those measures found to be stable (alpha > 0.8) at each speed were then examined for differences associated with speed. The tangential, radial, and medial-lateral forces were found to comprise approximately 55, 35, and 10% of the resultant force, respectively. In addition to duration of stroke and propulsion, the following variables were found to be stable and to differ with speed (1.3 m/s +/- SD; 2.2 m/s +/- SD): peak force tangential to the pushrim (45.9 +/- 17.9 N; 62.1 +/- 30 N), peak moment radial to the hub (9.8 +/- 4.5 N x m 13.3 +/- 6 N x m), maximum rate of rise of the tangential force (911.7 +/- 631.7 N/sec; 1262.3 +/- 570.7 N/sec), and maximum rate of rise of the moment about the hub (161.9 +/- 78.3 N x m/s; 255.2 +/- 115.4 N x m/s). This study found stable parameters that characterize pushrim forces during wheelchair propulsion and varied with speed. Almost 50% of the forces exerted at the pushrim are not directed toward forward motion and, therefore, either apply friction to the pushrim or are wasted. Ultimately, this type of investigation may provide insight into the cause and prevention of upper limb injuries in manual wheelchair users.
上肢疼痛在手动轮椅使用者中经常出现。分析轮椅推进过程中产生的轮辋力和轮毂力矩是深入了解这种疼痛原因的第一步。本研究的目的如下：描述轮椅推进过程中产生的力和力矩；获取表征轮辋力且统计稳定的变量；并确定这些变量如何随速度变化。对使用手动轮椅出行且手臂功能未受损的残奥会运动员进行了便利抽样（n = 6）测试。每位受试者在测力计上以1.3米/秒和2.2米/秒的速度推动标准轮椅。使用力和力矩感应轮辋以及运动分析系统获取生物力学数据。使用克朗巴哈系数评估了一些描述力和力矩曲线的变量的稳定性。然后检查那些在每种速度下都稳定（系数> 0.8）的测量值与速度相关的差异。发现切向力、径向力和内侧 - 外侧力分别约占合力的55%、35%和10%。除了冲程和推进的持续时间外，还发现以下变量是稳定的且随速度变化（1.3米/秒±标准差；2.2米/秒±标准差）：轮辋切向的峰值力（45.9±17.9牛；62.1±30牛）、轮毂径向的峰值力矩（9.8±4.5牛·米；13.3±6牛·米）、切向力的最大上升速率（911.7±631.7牛/秒；1262.3±570.7牛/秒）以及轮毂力矩的最大上升速率（161.9±78.3牛·米/秒；255.2±115.4牛·米/秒）。本研究发现了表征轮椅推进过程中轮辋力且随速度变化的稳定参数。施加在轮辋上的力几乎有50%并非直接用于向前运动，因此，要么对轮辋施加了摩擦力，要么被浪费了。最终，这类研究可能会为深入了解手动轮椅使用者上肢损伤的原因及预防提供见解。
