Walking for six minutes increases both simple reaction time and stepping reaction time in moderately disabled people with Multiple Sclerosis

Background: Walking ability and fatigue are often reported as the most disabling symptoms in Multiple Sclerosis (MS). Motor fatigue may contribute to reduced mobility, and is likely caused by both central and peripheral deterioration in neuromuscular function. Simple and choice stepping reaction time (RT) measures have the potential to detect walking induced changes in motor impairment. Objectives: The aim of this study was to assess the effect of six minutes of walking on simple and choice stepping RT in people with MS. Methods: 31 people with moderate walking disability and a diagnosis of MS completed simple and choice stepping RT tasks, and rated their levels of fatigue on a 100 mm visual analogue scale before and after a modified six minute walk test. Results: Subjects walked an average of 368(+/- 110)m in six minutes. Perceived fatigue increased following the six minute walk, as indicated by a 25(+/- 19.7)mm increase on the 100 mm visual analogue scale (p < 0.001). There was a significant increase in both hand (p=0.003) and foot (p=0.006) simple RT following the six minute walk. For choice stepping RT, response time was significantly slower (p=0.006) following the six minute walk, while movement time was unchanged (p=0.506). Conclusion: Simple and choice stepping reaction times are slower following six minutes of walking in people with MS. These findings suggest that walking-induced fatigue might lead to central slowing and slowed stepping performance. Further studies are needed to investigate the clinical relevance of these RT measures in relation to fall risk and therapeutic interventions to improve mobility and manage fatigue in people with MS. (C) 2014 Elsevier B.V. All rights reserved.