Hansen Clint, Rezzoug Nasser, Gorce Philippe, Isableu Brice
Aspetar Orthopaedic and Sports Medicine Hospital, Research Department, Doha, Qatar. .
J Appl Biomech. 2016 Jun;32(3):311-5. doi: 10.1123/jab.2015-0286. Epub 2016 Jan 18.
For the dominant limb, a velocity-dependent change in rotational axes during the kinesthetic control of unconstrained 3D arm rotations was reported, and thus the question arises if this can be reproduced for the nondominant arm. The rotation axes considered are the axes of minimum inertia (e3), the shoulder-center of mass axis (SH-CM), and the shoulder-elbow axis (SH-EL). The objective of this study was to examine whether the minimum inertia axis would constrain internal-external rotations of the shoulder at fast velocity. Participants performed cyclic rotations of their arms in 2 sensory conditions and at 2 velocities. The elbow configurations were either set to 90° or 140° to yield a constant separation between e3, SH-CM, and SH-EL. Our results showed that the limb's rotational axis coincide with the SH-EL axis across velocity conditions, although higher variability was seen at higher velocity. This was true for both the dominant and the nondominant arm. Together, the results showed that cognitive instruction prevented a velocity-dependent rotation axis change toward e3 and/or SH-CM, as proposed in the minimum inertia principle.
对于优势肢体，已有报道称在无约束的三维手臂旋转的动觉控制过程中，旋转轴存在速度依赖性变化，因此出现了一个问题，即非优势手臂是否也能再现这种情况。所考虑的旋转轴是最小惯性轴（e3）、肩-质心轴（SH-CM）和肩-肘轴（SH-EL）。本研究的目的是检验最小惯性轴在快速运动时是否会限制肩部的内外旋转。参与者在两种感觉条件下和两种速度下进行手臂的循环旋转。将肘部配置设置为90°或140°，以使e3、SH-CM和SH-EL之间保持恒定间距。我们的结果表明，尽管在较高速度下变异性更大，但在不同速度条件下，肢体的旋转轴均与SH-EL轴重合。优势手臂和非优势手臂都是如此。总体而言，结果表明，认知指令阻止了如最小惯性原理中所提出的朝向e3和/或SH-CM的速度依赖性旋转轴变化。
