The effects of fatigue on reaction time in people with multiple sclerosis

People with Multiple Sclerosis (MS) often report fatigue and reduced capacity for walking as some of their most disabling symptoms (1-3). Indeed, fatigue is often reported after relatively short bouts of walking. However, the functional consequences of this fatigue are not well known. We were interested in how walking might impair motor functions that are important for daily life activities, such as safe ambulation.


An example of a single trial of the Choice Stepping Reaction-time Test.

An example of a single trial of the Choice Stepping Reaction-time Test.


We asked 31 people with MS to walk for six minutes and recorded their hand and stepping reaction times before and after. They reported increased levels of fatigue after walking. Participants had increased hand and foot simple reaction time after the six minute walk; that is they responded slower when pressing a button with their finger or foot in response to a light stimulus. Stepping reaction time, which involved a choice response, showed a slower initiation of the response, while step movement time was unchanged.  



The decline in simple hand and foot reaction time demonstrates that walking has a general negative effect on central aspects of motor control. Additionally, the reduction in choice stepping reaction time demonstrates the associated functional implications of this impairment on stepping ability. Reducing walking-related fatigue and increasing walking capacity in people with MS is an important therapeutic goal and should lead to improved function in activities of daily life.



Barr C, McLoughlin J, Lord SR, Crotty M, Sturnieks DL (2014).Walking for six minutes increases both simple reaction time and stepping reaction time in moderately disabled people with Multiple Sclerosis. Mult Scler Relat Disord 3, 457–462.


Johansson S, Ytterberg C, Claesson IM, Lindberg J, Hillert J, Andersson M, et al (2007). High concurrent presence of disability in multiple sclerosis. Associations with perceived health. J Neurol 254, 767–73.

Bakshi R (2003). Fatigue associated with multiple sclerosis: diagnosis, impact and management. Mult Scler 9, 219–27.

Schwid SR, Covington M, Segal BM, Goodman AD (2002). Fatigue in multiple sclerosis: current understanding and future directionsJ Rehabil Res Dev 39, 211–24.

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