Summary of Human Ankle Mechanical Impedance During Walking

Abstract

The human ankle joint plays a critical role during walking and understanding the biomechanical factors that govern ankle behavior and provides fundamental insight into normal and pathologically altered gait. Previous researchers have comprehensively studied ankle joint kinetics and kinematics during many biomechanical tasks, including locomotion; however, only recently have researchers been able to quantify how the mechanical impedance of the ankle varies during walking. The mechanical impedance describes the dynamic relationship between the joint position and the joint torque during perturbation, and is often represented in terms of stiffness, damping, and inertia. The purpose of this short communication is to unify the results of the first two studies measuring ankle mechanical impedance in the sagittal plane during walking, where each study investigated differing regions of the gait cycle. Rouse et al. measured ankle impedance from late loading response to terminal stance, where Lee et al. quantified ankle impedance from pre-swing to early loading response. While stiffness component of impedance increases significantly as the stance phase of walking progressed, the change in damping during the gait cycle is much less than the changes observed in stiffness. In addition, both stiffness and damping remained low during the swing phase of walking. Future work will focus on quantifying impedance during the “push off” region of stance phase, as well as measurement of these properties in the coronal plane.

Estimation of Time-Varying, Intrinsic and Reflex Dynamic Joint Stiffness during Movement. Application to the Ankle Joint

“…The variation of the intrinsic stiffness parameters, shown in Figures 3A–C, was based on results reported by Lee et al (2016). …”

Impedance of the Human Ankle During Standing for Posture Control

“…The impedance modulation of the human ankle is required for stable walking. The estimation of the time-varying impedance modulation of the human ankle is the focus of research by different groups [1,2].The human body can be modeled as an inverted pendulum with a rocker shaped based [3]. In this model, the body is unstable if the radius of the rocker base is smaller than the height of the center of the mass.…”

Effects of supraspinal feedback on human gait: rhythmic auditory distortion

“…We and others have reported that subjects can alter their gait patterns based on implicit changes in gait visual feedback [23][24][25] and mechanical perturbation [26] with the visual distortions having a longer after-effect than mechanical perturbation [27]. Here, we expand our work on visual and mechanical perturbations and report on the effects of auditory distortion on gait [28].…”