Interdisciplinary Graduate Program in Health Sciences, Universidade Cruzeiro do Sul, São Paulo, Rua Galvão Bueno, 868, Liberdade, São Paulo, SP 01506-000, Brazil.
Graduate Program in Physical Therapy. Universidade Cidade de São Paulo, São Paulo, Rua Cesário Galeno, 475, Tatuapé, São Paulo, SP 03071-000, Brazil.
Gait Posture. 2024 Jun;111:150-155. doi: 10.1016/j.gaitpost.2024.04.025. Epub 2024 Apr 25.
The vertical toe position at minimum toe clearance (MTC) in the swing phase is critical for walking safety. Consequently, the joints involved should be strictly controlled and coordinated to stabilize the foot at MTC. The uncontrolled manifold (UCM) hypothesis framework has been used to determine the existence of synergies that stabilize relevant performance variables during walking. However, no study investigated the presence of a multi-joint synergy stabilizing the foot position at MTC and the effects of age and walking speed on this synergy.
Is there a multi-joint synergy stabilizing MTC during treadmill walking? Does it depend on the persons' age and walking speed?
Kinematic data from 23 young and 15 older adults were analyzed using the UCM approach. The participants walked on a treadmill at three speeds: slow, self-selected, and fast. The sagittal and frontal joint angles from the swing and stance legs and pelvis obliquity were used as motor elements and the vertical toe position at MTC was the performance variable. The variances in the joint space that affected (V, 'bad' variance) and did not affect (V, 'good' variance) the toe position at MTC and the synergy index (ΔV) were computed.
The ΔV>0 was revealed for all subjects. Walking speed did not affect ΔV in older adults, whereas ΔV reduced with speed in young adults. ΔV was higher for older than for young adults at self-selected and fast speeds, owing to a lower V in the older group.
The vertical toe position at MTC was stabilized by a strong multi-joint synergy. In older adults, this synergy was stronger, as they were better at limiting V than young adults. Reduced V in older adults could be caused by more constrained walking, which may be associated with anxiety due to walking on a treadmill.
摆动相时最小触地间隙（MTC）处的垂直足位对于步行安全至关重要。因此，相关关节应严格控制和协调，以在 MTC 处稳定足部。无控制流形（UCM）假设框架已被用于确定在行走过程中稳定相关性能变量的协同作用的存在。然而，尚无研究调查在 MTC 处稳定足部位置的多关节协同作用的存在，以及年龄和步行速度对这种协同作用的影响。
在跑步机行走时是否存在稳定 MTC 的多关节协同作用？它是否取决于人的年龄和步行速度？
使用 UCM 方法分析了 23 名年轻和 15 名老年参与者的运动学数据。参与者在三种速度（慢、自定和快）下在跑步机上行走。摆动和支撑腿以及骨盆倾斜的矢状面和额状面关节角度被用作运动元素，MTC 处的垂直足位是性能变量。计算影响（V，“不良”方差）和不影响（V，“良好”方差）MTC 处足位的关节空间方差（V）以及协同指数（ΔV）。
所有受试者均显示ΔV>0。在老年人中，行走速度不影响ΔV，而在年轻人中，随着速度的增加，ΔV 降低。在自定和快速速度下，老年人的ΔV 高于年轻人，这是由于老年人的 V 较低。
MTC 处的垂直足位由一个强大的多关节协同作用稳定。在老年人中，这种协同作用更强，因为他们比年轻人更擅长限制 V。老年人的 V 降低可能是由于行走受限，这可能与在跑步机上行走时的焦虑有关。
