Department of Biology, Northeastern University, Boston, MA, USA.
Department of Neurology, Tor Vergata Polyclinc, Rome, Italy.
J Neuroeng Rehabil. 2022 Sep 10;19(1):97. doi: 10.1186/s12984-022-01067-7.
Numerous studies showed that postural balance improves through light touch on a stable surface highlighting the importance of haptic information, seemingly downplaying the mechanical contributions of the support. The present study examined the mechanical effects of canes for assisting balance in healthy individuals challenged by standing on a beam.
Sixteen participants supported themselves with two canes, one in each hand, and applied minimal, preferred, or maximum force onto the canes. They positioned the canes in the frontal plane or in a tripod configuration. Statistical analysis used a linear mixed model to evaluate the effects on the center of pressure and the center of mass.
The canes significantly reduced the variability of the center of pressure and the center of mass to the same level as when standing on the ground. Increasing the exerted force beyond the preferred level yielded no further benefits, although in the preferred force condition, participants exploited the altered mechanics by resting their arms on the canes. The tripod configuration allowed for larger variability of the center of pressure in the task-irrelevant anterior-posterior dimension. High forces had a destabilizing effect on the canes: the displacement of the hand on the cane handle increased with the force.
Given this static instability, these results show that using canes can provide not only mechanical benefits but also challenges. From a control perspective, effort can be reduced by resting the arms on the canes and by channeling noise in the task-irrelevant dimensions. However, larger forces exerted onto the canes can also have destabilizing effects and the instability of the canes needs to be counteracted, possibly by arm and shoulder stiffness. Insights into the variety of mechanical effects is important for the design of canes and the instructions of how to use them.
许多研究表明，在稳定表面上进行轻触可以改善姿势平衡，这突出了触觉信息的重要性，似乎淡化了支撑的机械贡献。本研究通过让健康个体站在平衡木上来测试手杖对平衡的辅助作用的机械影响。
16 名参与者双手各持一根手杖，用最小、最适或最大的力施加在手杖上。他们将手杖放在额状面或三脚架配置中。统计分析采用线性混合模型来评估对压力中心和质心的影响。
手杖显著降低了压力中心和质心的变异性，使其达到与站在地面上相同的水平。施加的力超过最适水平不会带来进一步的好处，尽管在最适力条件下，参与者通过将手臂放在手杖上来利用改变后的力学。三脚架配置允许压力中心在任务无关的前后维度上有更大的变异性。高力对手杖有不稳定的影响：手柄上的手的位移随力的增加而增加。
鉴于这种静态不稳定，这些结果表明，使用手杖不仅可以提供机械效益，还可以带来挑战。从控制的角度来看，通过将手臂放在手杖上并将噪声引导到任务无关的维度，可以减少用力。然而，施加在手杖上的更大力也可能具有不稳定的影响，需要对抗手杖的不稳定性，这可能需要通过手臂和肩部的僵硬来实现。对手杖的各种机械效果的深入了解对于手杖的设计和使用说明都很重要。
