Oxygen cost of walking in persons with multiple sclerosis: disability matters, but why?

Brian M Sandroff,Rachel E Klaren,Lara A Pilutti,Robert W Motl

doi:10.1155/2014/162765

Brian M Sandroff, Rachel E Klaren + Show 2 more

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https://doi.org/10.1155/2014/162765

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Abstract

Background. The oxygen cost (O2 cost) of walking is elevated in persons with MS, particularly as a function of increasing disability status. Objective. The current study examined symptomatic (i.e., fatigue, pain, anxiety, and depression) and gait (i.e., velocity, cadence, and step length) variables that might explain why disability status is associated with O2 cost of walking in persons with MS. Materials and Methods. 82 participants completed the Patient-Determined Disease Steps, Fatigue Severity Scale, McGill Pain Questionnaire, and Hospital Anxiety and Depression Scale and undertook 2 trials of walking on a GAITRite electronic walkway. Participants then completed a six-minute walk test with concurrent assessment of expired gases for quantifying oxygen consumption and O2 cost of walking. Results. Disability (r = 0.55) as well as fatigue (r = 0.22), gait velocity (r = −0.62), cadence (r = −0.73), and step length (r = −0.53) were associated with the O2 cost of walking. Cadence (β = −0.67), but not step length (β = −0.14) or fatigue (β = −0.10), explained the association between disability and the O2 cost of walking. Conclusions. These results highlight cadence as a target of rehabilitation for increasing metabolic efficiency during walking among those with MS, particularly as a function of worsening disability.

Highlights

The impairment of walking is a hallmark feature of neurological diseases such as multiple sclerosis (MS) [1, 2]
The current study examined potential symptomatic and gait variables as factors that might explain the association between disability status and the oxygen cost (O2 cost) of walking in a relatively large sample of 82 persons with MS who had a broad range of disability
Participants were contacted (a) by mail through a flyer that was sent to patients in North American Research Committee on Multiple Sclerosis (NARCOMS) registry or (b) by e-mail through a flyer that was sent to participants in a database from previous studies conducted in our laboratory over the past five years

Summary

Introduction

The impairment of walking is a hallmark feature of neurological diseases such as multiple sclerosis (MS) [1, 2]. There is evidence that persons with MS expend more energy than controls without MS when performing comparable walking assessments (e.g., 6 minutes of walking at 3 mph) [3, 4] This increase in energy expenditure can be expressed in terms of the oxygen cost (O2 cost) of walking. The current study examined symptomatic (i.e., fatigue, pain, anxiety, and depression) and gait (i.e., velocity, cadence, and step length) variables that might explain why disability status is associated with O2 cost of walking in persons with MS. These results highlight cadence as a target of rehabilitation for increasing metabolic efficiency during walking among those with MS, as a function of worsening disability

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Discussion

Conclusion