Do gait stability and arm swing affect walking speed during the 6-minute walk test in persons with Multiple Sclerosis?

Abstract

Fatigue is a major complaint in patients with multiple sclerosis (pwMS) [1]. Previous research identified walking fatigability in pwMS by assessing the change in distance walked between minute 6 and 1 of the 6-Minute Walk Test (6MWT) [2]. Further, pwMS show lower limb gait deficits [3], resulting in decreased gait stability compared to healthy controls [4]. Additionally, upper limb movements can be altered in pwMS due to direct MS lesions [5], which have an important role during gait [6]. Therefore, the aim was to assess to what extent change in walking speed in pwMS is associated by changes in gait stability and arm swing from minute 6 to 1 of the 6MWT. Participants were included if they had: MS, age between 18–65, disease severity score from 1 to 5.5 on Expanded Disability Status Scale, ability to walk without walking aids. Participants were excluded if they had: a relapse 3 months, lower limb fracture 12 months, or lower limb botulinum toxin 6 months prior to the study. Participants performed the 6MWT on the CAREN (Motek), equipped with the Human Body lower limb and trunk model, including extra markers for arm swing (acromion and ulnar styloid). Participants walked as fast as possible using self-paced mode. Two familiarization rounds of 3 min, incl. breaks, were provided. Step width and variability of spatiotemporal parameters (i.e. step width, -length & -time) were used to assess gait stability [7]. Arm swing length was calculated as the difference between maximum anterior and posterior hand position. Most affected side was taken into account and defined as the side with greatest motor impairment (i.e. spasticity and/or weakness). Difference scores between minute 6 and 1 of the 6MWT were used for analyses. First, one-tailed Pearson correlations between gait stability measures & arm swing, and walking speed during the 6MWT were tested. Then one-tailed partial correlations were assessed to determine whether gait stability measures influenced walking speed when taking arm swing into account. Finally, significant factors were used in generalized estimation equations (GEE) to determine the extent of their effect on walking speed and possible interactions. Preliminary results included data of 11 pwMS(Table1/T1). Walking speed was significantly related to step length variability, step time variability and arm swing(T1). Partial correlation of step length variability and step time variability remained significant when controlling for arm swing(T1). GEE determined interaction effects between step length variability, step time variability and arm swing on walking speed(T1).Download : Download high-res image (390KB)Download : Download full-size image Results indicate that both gait stability and arm swing are significantly associated to walking speed during 6MWT in pwMS. These outcomes have a separate effect on walking speed as well as an interaction effect. Future studies could investigate whether gait stability and arm swing might be underlying factors driving walking fatigability in pwMS.