The effect of external lateral stabilization on the use of foot placement to control mediolateral stability in walking and running.

Mohammadreza Mahaki,Sjoerd M Bruijn,Jaap H Van Dieën

doi:10.7717/peerj.7939

Mohammadreza Mahaki, Sjoerd M Bruijn + Show 1 more

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https://doi.org/10.7717/peerj.7939

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Abstract

It is still unclear how humans control mediolateral (ML) stability in walking and even more so for running. Here, foot placement strategy as a main mechanism to control ML stability was compared between walking and running. Moreover, to verify the role of foot placement as a means to control ML stability in both modes of locomotion, this study investigated the effect of external lateral stabilization on foot placement control. Ten young adults participated in this study. Kinematic data of the trunk (T6) and feet were recorded during walking and running on a treadmill in normal and stabilized conditions. Correlation between ML trunk CoM state and subsequent ML foot placement, step width, and step width variability were assessed. Paired t-tests (either SPM1d or normal) were used to compare aforementioned parameters between normal walking and running. Two-way repeated measures ANOVAs (either SPM1d or normal) were used to test for effects of walking vs. running and of normal vs. stabilized condition. We found a stronger correlation between ML trunk CoM state and ML foot placement and significantly higher step width variability in walking than in running. The correlation between ML trunk CoM state and ML foot placement, step width, and step width variability were significantly decreased by external lateral stabilization in walking and running, and this reduction was stronger in walking than in running. We conclude that ML foot placement is coordinated to ML trunk CoM state to stabilize both walking and running and this coordination is stronger in walking than in running.

Highlights

It is still unclear how humans walk and run with such ease, that is, stable and with low energy costs
Small perturbations may be controlled by passive dynamics without Central Nervous System (CNS) involvement, and larger instabilities in the system are countered by active control, which requires sensing of perturbations, generating appropriate motor commands, and producing compensatory motions (Kuo & Donelan, 2010)
In line with our second hypothesis, we found a significantly stronger correlation between ML trunk Center of Mass (CoM) state and subsequent ML foot placement in walking than in running from 0–100% of the swing phase (Figs. 4 and 5), as well as a significantly greater step width variability (t (1,9) = 4.17, p = 0.002) in walking than running, the differences of step width was not significant (t (1,9) = 2.21, p = 0.05) (Figs. 6A and 6B)

Summary

Introduction

It is still unclear how humans walk and run with such ease, that is, stable and with low energy costs. I.e., maintaining a steady gait pattern without falling in the face of perturbations, requires control of the Center of Mass (CoM) relative to the Base of Support (BoS) (Arellano & Kram, 2011b; Bauby & Kuo, 2000; Kuo & Donelan, 2010). Motions of the CoM relative to the BoS are thought to be. Small perturbations may be controlled by passive dynamics without Central Nervous System (CNS) involvement, and larger instabilities in the system are countered by active control, which requires sensing of perturbations, generating appropriate motor commands, and producing compensatory motions (Kuo & Donelan, 2010)

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