Using smartphone accelerometry to assess the relationship between cognitive load and gait dynamics during outdoor walking

Simon Ho,Amelia Mohtadi,Kash Daud,Todd C Handy,Ute Leonards

doi:10.1038/s41598-019-39718-w

Simon Ho, Amelia Mohtadi + Show 3 more

Open Access

https://doi.org/10.1038/s41598-019-39718-w

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Abstract

Research has demonstrated that an increase in cognitive load can result in increased gait variability and slower overall walking speed, both of which are indicators of gait instability. The external environment also imposes load on our cognitive systems; however, most gait research has been conducted in a laboratory setting and little work has demonstrated how load imposed by natural environments impact gait dynamics during outdoor walking. Across four experiments, young adults were exposed to varying levels of cognitive load while walking through indoor and outdoor environments. Gait dynamics were concurrently recorded using smartphone-based accelerometry. Results suggest that, during indoor walking, increased cognitive load impacted a range of gait parameters such as step time and step time variability. The impact of environmental load on gait, however, was not as pronounced, with increased load associated only with step time changes during outdoor walking. Overall, the present work shows that cognitive load is related to young adult gait during both indoor and outdoor walking, and importantly, smartphones can be used as gait assessment tools in environments where gait dynamics have traditionally been difficult to measure.

Highlights

Dynamic adjustment of gait is seen as a way to minimize energy cost during ambulation[1,2], and humans continuously optimize energetic cost in real-time, even if the savings are small[3]
Our results show significant differences between our low and high load conditions, across multiple gait parameters, suggesting that cognitive load may act as an additional contributor to young adult gait control, over and above any effect verbal articulation may have
We hypothesized that fractal dimension (FD) of an image would be associated with the dynamics of gait

Summary

Introduction

Dynamic adjustment of gait is seen as a way to minimize energy cost during ambulation[1,2], and humans continuously optimize energetic cost in real-time, even if the savings are small[3]. The relationship between gait dynamics and cognition is often studied with dual-task paradigms: if walking requires cognitive resources, increasing the difficulty of a concurrent secondary task should result in changes to the dynamics of gait (e.g. speed, step time variability, regularity). This effect has been well documented; for example, research has shown that walking under high cognitive load is associated with worse performance on a stepping stone task[12], reduced ability to avoid obstacles[10], reduced gait speed and leg swing time[13], or increased number of missteps in complex walking environments[14]. Explicitly manipulated load in the lab via a cognitive dual-task may not have the same impact on gait as load that is inherent to an outdoor environment

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