Training propulsion: Locomotor adaptation to accelerations of the trailing limb

Walking function, which is critical to performing many activities of daily living, is commonly assessed by walking speed. Walking speed is dependent on propulsion, which is governed by ankle moment and the posture of the trailing limb during push-off. Here, we present a new gait training paradigm that utilizes a dual belt treadmill to train both components of propulsion by accelerating the belt of the trailing limb during push off. Accelerations require subjects to produce greater propulsive force to counteract inertial effects, and increase trailing limb angle through increased belt velocity.We hypothesized that exposure to our training p rogram would produce after effects in propulsion mechanics and, consequently, walking speed. We tested our protocol on healthy subjects at two acceleration magnitudes-Perceptible (PE), and Imperceptible, (IM)-and compared their results to a third control group (VC) that walked at a higher velocity during training.Results show that the PE group significantly increased walking speed following training (mean ± s.e.m: 0.073 ± 0.013 m/s, p < 0.001). The change in walking speed in the IM and VC groups was not significant at the group level (IM: 0.032 ± 0.013 m/s; VC: -0.003 ± 0.013 m/s). Responder analysis showed that changes in push-off posture and in neuro-motor control of ankle plantar-flexor muscles contributed to the larger increases in gait speed measured in the PE group compared to the IM and VC groups. Analysis of the effects during and after training suggest that changes in neuromotor coordination are consistent with usedependent learning.

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Simple within-stride changes in treadmill speed can drive selective changes in human gait symmetry

Browne

Stenum

Padmanabhan

et al. 2022

Preprint

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BackgroundMillions of people worldwide are affected by clinical conditions that result in gait asymmetry (e.g., stroke, cerebral palsy, lower limb amputation). There is a need for customizable rehabilitation approaches that can flexibly target different aspects of gait asymmetry with minimal need for specialized equipment. Here, we studied how simple within-stride changes in treadmill speed could drive selective, predictable changes in human gait symmetry.MethodsIn Experiment 1, ten healthy young adults walked on an instrumented treadmill with and without a closed-loop controller engaged. The controller changed the treadmill speed to 1.50 m/s or 0.75 m/s depending on whether the right or left leg generated propulsive (i.e., forward-directed) ground reaction forces, respectively. In Experiment 2, a separate group of ten healthy young adults walked on the treadmill with and without an open-loop controller engaged. This controller changed the treadmill speed to 1.50 m/s or 0.75 at a prescribed time interval. We used a metronome to guide the participants to step at a series of different time points relative to the controller-driven speed change. We collected kinematic and kinetic data in Experiments 1 and 2.ResultsIn Experiment 1, participants walked with asymmetric kinematics and ground reaction forces when the closed-loop controller was engaged. The leg that accelerated during propulsion (right leg) showed a smaller leading limb angle and a larger trailing limb angle than the leg that decelerated during propulsion (left leg). The right leg also generated smaller propulsive forces than the left leg. In Experiment 2, the patterns of asymmetry in spatiotemporal gait parameters, kinematics, and ground reaction forces depended on the timing of the speed change within the gait cycle. Step times, leading limb angles, and peak propulsion became asymmetric when the treadmill speed changed early in stance. When the treadmill speed changed later in stance, step lengths, step times, and propulsion impulses became asymmetric.ConclusionsSimple manipulations of treadmill speed can drive predictable, selective changes in human gait symmetry. Future work will explore this customizable technique as a potential approach for restoring gait symmetry in clinical populations.

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Training propulsion: Locomotor adaptation to accelerations of the trailing limb

Cited by 3 publications

References 15 publications

Adaptive treadmill control can be manipulated to increase propulsive impulse while maintaining walking speed

Adaptive treadmill control can be manipulated to increase propulsive impulse while maintaining walking speed

A Controlled Slip: Training Propulsion via Acceleration of the Trailing Limb

Simple within-stride changes in treadmill speed can drive selective changes in human gait symmetry

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