Contribution of the support limb in control of angular momentum after tripping
Contribution of the support limb in control of angular momentum after tripping
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DOI：
10.1016/j.jbiomech.2004.02.038
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发表时间：
2004-12-01
影响因子：
2.4
通讯作者：
van Dieën, JH
中科院分区：
文献类型：
--
作者：
Pijnappels, M;Bobbert, MF;van Dieën, JH
当从与障碍物碰撞中获得的向前角动量未被阻止时，被障碍物绊倒可能会导致跌倒。角动量可以通过将恢复肢正确放置在身体前方来限制，但也可能通过推离期间对侧支撑肢的反应来限制。本研究的目的是通过为恢复肢体的正确定位提供时间和间隙，并通过在推离过程中限制身体的角动量来量化支撑肢体对绊倒后恢复的贡献程度。十二名年轻人在荡秋千时，在平台上行走时，多次被障碍物绊倒。测量支撑肢处的运动学和地面反作用力。角动量的量化基于外部力矩的计算，外部力矩等于物体角动量的变化率。结果表明，所有受试者在脚接触障碍物时角动量都有类似的增加，平均为 11.4 kg m(2) s(-1)。在所有受试者中，支撑肢通过为恢复肢的正确定位提供时间和间隙，在绊倒后的恢复中发挥了作用，如身体抬高（6%）和恢复步幅中骨盆前移增加（43%）所示。几乎所有受试者都能够在支撑肢推出时抑制身体向前的角动量。恢复肢还需要进一步实现更少的角动量。支撑肢反应质量的降低可能是增加老年人跌倒风险的因素之一。 (C) 2004 Elsevier Ltd. 保留所有权利。
Tripping over an obstacle can result in a fall when the forward angular momentum, obtained from impact with the obstacle, is not arrested. Angular momentum can be restrained by proper placement of the recovery limb, anteriorly of the body, but possibly also by a reaction in the contralateral support limb during push-off. The purpose of this study was to quantify the extent to which the support limb contributes to recovery after tripping by providing time and clearance for proper positioning of the recovery limb, and by restraining the angular momentum of the body during push-off. Twelve young adults were repeatedly tripped over an obstacle during mid-swing, while walking over a platform. Kinematics and ground reaction forces at the support limb were measured. Quantification of the angular momentum was based on calculation of the external moment, which equals the rate of change in the angular momentum of the body. Results showed that all subjects acquired a similar increase in angular momentum during foot-obstacle contact, on average 11.4 kg m(2) s(-1). In all subjects, the support limb played a role in recovery after tripping by providing time and clearance for proper positioning of the recovery limb, as indicated by body elevation (6%) and the increased forward pelvis displacement over recovery stride (43%). Almost all subjects were also able to restrain the forward angular momentum of the body during push-off by the support limb. Less angular momentum remained to be further accomplished by the recovery limb. Reductions in the quality of the support limb responses may be among the factors that increase the risk of falling in the elderly. (C) 2004 Elsevier Ltd. All rights reserved.