van der Woude L H, Bosmans I, Bervoets B, Veeger H E
Institute for Fundamental and Clinical Human Movement Sciences, Faculty of Human Movement Sciences, Vrije Universiteit, Amsterdam, The Netherlands.
J Med Eng Technol. 2000 Nov-Dec;24(6):242-9. doi: 10.1080/030919000300037168.
Handrim wheelchair propulsion is a straining form of ambulation. In contrast, arm crank exercise in laboratory settings has shown a higher degree of gross mechanical efficiency and increased levels of peak power output. Moreover, arm crank exercise can be conducted at different gear ratios and in asynchronic or synchronic mode. Although tricycle crank exercise or handcycling has become increasingly popular for recreational use, sports and outdoor wheeling over the last decade, today little is known about the cardiopulmonary strain in handcycling. The physiological and subjective responses during handcycling were evaluated in a group of 12 male non-wheelchair users (age 24.6 +/- 2.7 yr; body weight 73.7 +/- 9.7 kg). During an incremental submaximal exercise test on a motor driven treadmill (velocity: 1.8 ms-1; an incremental slope of 1% per 3 min; 0-3%; mean power output of the subject group varied between 7.6 +/- 1.6 W and 47.5 +/- 6.2 W), effects of asynchronic and synchronic crank settings and three different gear ratios (1:0.42, 1:0.59, 1:0.74 (or 24, 36 and 44 rpm)) were evaluated in a random testing sequence. Significantly lower levels of mean oxygen uptake, ventilation, relative heart rate and oxygen uptake were seen during synchronic arm use and for the lighter gear ratios (i.e. higher movement frequency; 44 rpm). Subjective local perceived discomfort showed similar trends. Conversely, gross mechanical efficiency appeared higher for these conditions. The need for strong medio-lateral stabilizing muscle effort during asynchronic arm use (to ensure a proper wheeling direction as well as simultaneous power transfer to the cranks) and the effective use of the trunk in this subject group may explain the advantage of synchronic arm use. Whether this advantage is consolidated among wheelchair confined individuals needs further study. Apart from the important effects of a shift in force--velocity characteristics of the contracting muscles with varying gear ratios, increased static finger flexor and arm muscle activity may explain the increased strain in the somewhat unnatural heavy gear condition (24 rpm) at the studied velocity. Results need to be re-evaluated for wheelchair user populations and different higher velocities and power conditions. Moreover, other aspects of the wheelchair--user interface must be studied in order to generate optimum fitting and design guidelines for different user groups and conditions of use.
手摇轮椅推进是一种费力的移动方式。相比之下，实验室环境中的手臂曲柄运动已显示出更高的总体机械效率和更高的峰值功率输出水平。此外，手臂曲柄运动可以在不同的传动比下以异步或同步模式进行。尽管在过去十年中，三轮曲柄运动或手摇车在娱乐、体育和户外出行方面越来越受欢迎，但目前对于手摇车中的心肺负荷了解甚少。对一组12名男性非轮椅使用者（年龄24.6±2.7岁；体重73.7±9.7千克）在手摇车过程中的生理和主观反应进行了评估。在电动跑步机上进行递增亚极量运动测试期间（速度：1.8米/秒；每3分钟递增坡度1%；0 - 3%；受试者组的平均功率输出在7.6±1.6瓦和47.5±6.2瓦之间变化），以随机测试顺序评估了异步和同步曲柄设置以及三种不同传动比（即1:0.42、1:0.59、1:0.74（或24、36和44转/分钟））的影响。在同步手臂使用和较轻传动比（即较高运动频率；44转/分钟）时，平均摄氧量、通气量、相对心率和摄氧量水平显著降低。主观局部感知不适呈现类似趋势。相反，在这些条件下总体机械效率似乎更高。在异步手臂使用期间需要强大的中外侧稳定肌肉力量（以确保正确的行进方向以及同时将动力传递到曲柄），并且该受试者组中躯干的有效使用可能解释了同步手臂使用的优势。这种优势在轮椅受限个体中是否巩固需要进一步研究。除了随着传动比变化收缩肌肉的力 - 速度特性发生变化的重要影响外，静态手指屈肌和手臂肌肉活动增加可能解释了在所研究速度下在某种程度上不自然的重档条件（24转/分钟）下增加的负荷。对于轮椅使用者群体以及不同的更高速度和功率条件，结果需要重新评估。此外，必须研究轮椅 - 用户界面的其他方面，以便为不同用户群体和使用条件生成最佳适配和设计指南。
