van Dijk Marit P, Hoozemans Marco J M, Berger Monique A M, Veeger DirkJan H E J
Department of Biomechanical Engineering, Delft University of Technology, Delft, The Netherlands.
Department of Human Movement Sciences, Faculty of Behavioural and Movement, Sciences, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands.
J Biomech. 2024 Jan;163:111927. doi: 10.1016/j.jbiomech.2024.111927. Epub 2024 Jan 4.
In wheelchair sports, there is an increasing need to monitor mechanical power in the field. When rolling resistance is known, inertial measurement units (IMUs) can be used to determine mechanical power. However, upper body (i.e., trunk) motion affects the mass distribution between the small front and large rear wheels, thus affecting rolling resistance. Therefore, drag tests - which are commonly used to estimate rolling resistance - may not be valid. The aim of this study was to investigate the influence of trunk motion on mechanical power estimates in hand-rim wheelchair propulsion by comparing instantaneous resistance-based power loss with drag test-based power loss. Experiments were performed with no, moderate and full trunk motion during wheelchair propulsion. During these experiments, power loss was determined based on 1) the instantaneous rolling resistance and 2) based on the rolling resistance determined from drag tests (thus neglecting the effects of trunk motion). Results showed that power loss values of the two methods were similar when no trunk motion was present (mean difference [MD] of 0.6 ± 1.6 %). However, drag test-based power loss was underestimated up to -3.3 ± 2.3 % MD when the extent of trunk motion increased (r = 0.85). To conclude, during wheelchair propulsion with active trunk motion, neglecting the effects of trunk motion leads to an underestimated mechanical power of 1 to 6 % when it is estimated with drag test values. Depending on the required accuracy and the amount of trunk motion in the target group, the influence of trunk motion on power estimates should be corrected for.
在轮椅运动中，对现场机械功率进行监测的需求日益增加。当滚动阻力已知时，惯性测量单元（IMU）可用于确定机械功率。然而，上身（即躯干）运动影响小前轮和大后轮之间的质量分布，从而影响滚动阻力。因此，常用于估计滚动阻力的阻力测试可能并不有效。本研究的目的是通过比较基于瞬时阻力的功率损失和基于阻力测试的功率损失，来研究躯干运动对手轮圈驱动轮椅时机械功率估计的影响。在轮椅推进过程中，分别进行了无躯干运动、适度躯干运动和完全躯干运动的实验。在这些实验中，功率损失是基于以下两点确定的：1）瞬时滚动阻力；2）基于阻力测试确定的滚动阻力（从而忽略躯干运动的影响）。结果表明，当不存在躯干运动时，两种方法的功率损失值相似（平均差异[MD]为0.6±1.6%）。然而，当躯干运动程度增加时，基于阻力测试的功率损失被低估高达-3.3±2.3%MD（r=0.85）。总之，在有主动躯干运动的轮椅推进过程中，当用阻力测试值估计时，忽略躯干运动的影响会导致机械功率被低估1%至6%。根据目标群体所需的精度和躯干运动的程度，应校正躯干运动对功率估计的影响。
