The control of balance and locomotion
Date
2019
Authors
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Journal ISSN
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Publisher
University of Delaware
Abstract
We have established that humans use at least three different balance mechanisms to push against the ground to regulate balance during walking. (i) The lateral ankle mechanism activates muscles surrounding the stance leg ankle to pull on the body during single stance. This shifts the center of pressure under the stance foot towards the perceived fall. (ii) The foot placement mechanism shifts the placement of the swing foot towards the perceived fall at the next step. On heel contact, this shifts the center of pressure towards the perceived fall. (iii) The push-off mechanism shifts weight between the two legs during double stance by modulating the ankle plantarflexion/dorsiflexion of the trailing foot. ☐ The focus of this dissertation was to determine the interdependent nature and adaptability of these balance mechanisms through the following aims. ☐ Aim 1) Identify how humans coordinate these three balance mechanisms throughout the gait cycle. Our analysis illustrates that, when earlier and larger modulation of the CoP occurs under the stance foot, less of a foot placement is needed. ☐ Aim 2) Investigate the effect of changes in cadence on balance control. We address this issue by studying the response to experimentally induced vestibular fall sensations at different cadences (Slow and Fast). We find that people use the lateral ankle mechanism more in the Slow condition and the foot placement mechanism more in the Fast condition. ☐ Aim 3) Determine how balance control changes in the presence of environmental constraints. We use virtual reality to create no-step zones on the ground, then induced fall stimuli when subjects are walking close to those zones. Preliminary results suggest there is no difference in the use of the balance mechanisms in the presence of virtual environmental constraints. ☐ The goal of this research is to provide a basic understanding of how the healthy human nervous system regulates balance to successfully stay upright while moving through the environment. The knowledge gained from this research will allow identification of changes in the balance mechanisms observed in populations with diminished balance control and create an avenue for intervention in modifying the use of specific balance mechanisms.