Contribution of feedback and feedforward strategies to locomotor adaptations
Contribution of feedback and feedforward strategies to locomotor adaptations
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DOI：
10.1152/jn.00473.2005
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发表时间：
2006-02-01
影响因子：
2.5
通讯作者：
Dietz, V
中科院分区：
文献类型：
--
作者：
Lam, T;Anderschitz, M;Dietz, V
本研究的目的是检查人类受试者使用的策略，以使其步行模式适应对臀部和膝盖运动施加的速度依赖阻力。受试者首先在跑步机上行走，下肢绑在外骨骼机器人步态矫形器上，腿部运动不受阻力（零条件）。随后，对左髋部和膝部运动施加与速度相关的阻力（力条件）。捕捉试验散布在整个实验中，以跟踪步行模式适应性变化的发展。在受力条件下迈出 188 步后，受试者继续在无效条件下再迈出 100 步（洗脱期）。记录并分析腿部肌肉活动和关节运动学。运动模式的适应性改变表明反馈和前馈控制策略的参与。反馈驱动的适应反映在摆动过程中股直肌和胫骨前肌活动的增加，这种情况立即发生，只有在存在阻力的情况下，而不是在接球试验期间。涉及前馈策略的运动适应反映在股二头肌和内侧腘绳肌的挥杆前活动增强上，这需要经验并在接球试验中持续存在。在清除期间，受试者表现出运动活动逐渐不适应控制水平。总之，步行模式的适应性变化是由适合克服阻力影响的步行模式的反馈和前馈调整驱动的。
The aim of this study was to examine the strategies used by human subjects to adapt their walking pattern to a velocity-dependent resistance applied against hip and knee movements. Subjects first walked on a treadmill with their lower limbs strapped to an exoskeletal robotic gait orthosis with no resistance against leg motions ( null condition). Afterward, a velocity-dependent resistance was applied against left hip and knee movements ( force condition). Catch trials were interspersed throughout the experiment to track the development of adaptive changes in the walking pattern. After 188 steps in the force condition, subjects continued to step in the null condition for another 100 steps ( washout period). Leg muscle activity and joint kinematics were recorded and analyzed. The adaptive modifications in the locomotor pattern suggest the involvement of both feedback and feedforward control strategies. Feedback-driven adaptations were reflected in increases in rectus femoris and tibialis anterior activity during swing, which occurred immediately, only in the presence of resistance, and not during the catch trials. Locomotor adaptations involving feedforward strategies were reflected in enhanced pre-swing activity in the biceps femoris and medial hamstrings muscles, which required experience and persisted in the catch trials. During washout subjects showed a gradual deadaptation of locomotor activity to control levels. In summary, adaptive changes in the walking pattern were driven by both feedback and feedforward adjustments in the walking pattern appropriate for overcoming the effects of resistance.