Energetic cost of walking and spasticity in persons with multiple sclerosis with moderate disability.

Abstract

The energetic cost of walking (Cw) is elevated in persons with multiple sclerosis (MS). This may be explained by spasticity and spatiotemporal parameters of gait. To examine the associations among Cw, spasticity of ankle plantarflexors, and spatiotemporal gait parameters in persons with MS who had moderate disability. The sample included 44 persons with MS who had moderate disability. Cw was measured over-ground during the 6-Minute Walk using indirect calorimetry and was calculated based on net oxygen consumption and walking speed (i.e., expressed ml·kg-1·m-1). Participants underwent the Modified Ashworth Scale as a measurement of spasticity and performed 4 trials of walking on a GAITRite electronic walkway for measurement of spatiotemporal gait parameters. Spasticity was positively correlated with Cw (r = 0.52, p < 0.05) and inversely correlated with cadence (r = -.45, p < 0.05) and step length (r = -0.40, p < 0.05). Cadence (r = -0.59, p < 0.05) and step length (r = -0.56, p < 0.05) were inversely correlated with Cw. The regression analysis indicated that spasticity explained significant variance in Cw, and cadence and step length accounted for the association. These results suggest that worse spasticity of the ankle plantarflexors and slower cadence and shorter step length, in turn, are responsible for elevated Cw among persons with MS with moderate disability. This supports the development of therapeutic, rehabilitation interventions delivered by clinicians for managing spasticity and the resulting Cw that may interfere with activities of daily living.