Biomechanics of spontaneous overground walk-to-run transition
Biomechanics of spontaneous overground walk-to-run transition
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自发地上步行到跑步转变的生物力学
DOI：
10.1242/jeb.087015
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发表时间：
2013
影响因子：
2.8
通讯作者：
D. De Clercq
中科院分区：
文献类型：
--
作者：
V. Segers;K. De Smet;I. Van Caekenberghe;P. Aerts;D. De Clercq
本研究的目的是描述人类自发步行到跑步过渡（WRT）的生物力学。在最少的指令后，17名身体活跃的受试者在装有仪器的跑道上进行了WRT，从而能够测量速度，加速度，时空变量，地面反作用力和3D运动学。本研究描述了（1）作为全身动力学的反映的身体质心（BCOM）的机械能波动和（2）关节运动学和动力学。与以前的研究一致，时空变量显示了从步行到跑步的一个过渡步骤突然切换。在这一步中，前进速度突然增加，即所谓的速度跳跃（0.42 m s-1）。在全身水平，这反映在BCOM能量的突然增加（0.83±0.14 J kg−1）以及动能和势能波动从异相到同相组织的突然变化。在过渡步骤期间，由于制动脉冲的减少，观察到与之前和之后的步骤相比更大的净推进脉冲。这表明，改变后的着陆配置（在前一次挥杆的最后40%期间准备）将身体置于最佳配置，以最大限度地减少这种制动冲动。我们假设这种配置也会引起一种反射，允许更强大的推力，从而产生足够的动力来完成过渡并启动第一个飞行阶段。这股强大的蹬地力量，也体现在垂直地面的反作用力上，陡然变成了奔跑的形态。
SUMMARY The purpose of the present study was to describe the biomechanics of spontaneous walk-to-run transitions (WRTs) in humans. After minimal instructions, 17 physically active subjects performed WRTs on an instrumented runway, enabling measurement of speed, acceleration, spatiotemporal variables, ground reaction forces and 3D kinematics. The present study describes (1) the mechanical energy fluctuations of the body centre-of-mass (BCOM) as a reflection of the whole-body dynamics and (2) the joint kinematics and kinetics. Consistent with previous research, the spatiotemporal variables showed a sudden switch from walking to running in one transition step. During this step there was a sudden increase in forward speed, the so-called speed jump (0.42 m s−1). At total body level, this was reflected in a sudden increase in energy of the BCOM (0.83±0.14 J kg−1) and an abrupt change from an out-of-phase to an in-phase organization of the kinetic and potential energy fluctuations. During the transition step a larger net propulsive impulse compared with the preceding and following steps was observed due to a decrease in the braking impulse. This suggests that the altered landing configuration (prepared during the last 40% of the preceding swing) places the body in an optimal configuration to minimize this braking impulse. We hypothesize this configuration also evokes a reflex allowing a more powerful push off, which generates enough power to complete the transition and launch the first flight phase. This powerful push-off was also reflected in the vertical ground reaction force, which suddenly changed to a running pattern.