Sandroff, B. M., Hillman, C. H., Benedict, R. H. B., & Motl, R. W. (2016). Acute effects of varying intensities of treadmill walking exercise on inhibitory control in persons with multiple sclerosis: A pilot investigation. Physiology & Behavior, 154, 20-27.
Summary: Alex X. Martínez
Multiple sclerosis (MS) is a neurodegenerative disease of the central nervous system (CNS) with an estimated prevalence of one per 1000 people in the United States. MS causes irreversible damage in the brain, resulting in the accumulation of physical and cognitive disability. Depression, unemployment, reduced quality of life, loss of independence, and impaired driving abilities are some of the outcomes associated with cognitive dysfunction. Cumulative and additive acute effects of single bouts of exercise on cognition during longitudinal aerobic exercise training interventions could result in meaningful improvements in cognition.
Results from a pilot study suggest that treadmill walking might exert the largest beneficial effects of exercise on reaction time (RT) which is behavior associated with better cognition on central executive tasks in MS. The current study examined the effects of 20-minute bouts of light, moderate, and vigorous intensity treadmill walking exercise compared with a quiet rest control condition on inhibitory control in fully ambulatory persons with MS.
The participants completed four experimental conditions that consisted of 20 minutes of light, moderate, and vigorous intensity treadmill walking exercise, and quiet rest in a randomized, counterbalanced order. A flanker task was used to measure the participant’s attention and inhibitory control of reaction time immediately prior to and following each condition.
Statistical analysis showed that: (a) light, moderate, and vigorous intensity treadmill walking exercise significantly and similarly reduced the cost of interfering stimuli on RT on flanker task relative to quiet rest; and (b) there were no effects of exercise intensity relative to quiet rest on accuracy outcomes from the modified flanker task. This suggests that light, moderate, and vigorous intensity treadmill walking exercise might be appropriate exercise stimuli for inclusion in an exercise training intervention for improving speed-related aspects of inhibitory control. The current results suggest that persons can begin a walking exercise program with bouts of light intensity exercise and still accumulate small acute improvements in interference control of RT. As comfort with treadmill walking exercise and/or cardiorespiratory fitness improves, participants with MS can gradually engage in more intense bouts of exercise over time (i.e., exercise progression) while accumulating additional improvements in interference control of RT.
Future research should consider examining the effects of treadmill walking exercise training on brain structure and function in regions associated with interference control and cognitive processing speed in persons with mild MS disability. The proposed mechanisms for how acute exercise improves cognition involve increased cerebral blood flow perfusion and cortical activation. These mechanisms and other possible mechanisms should be address in future studies. This line of research has the potential to ultimately provide clinicians and patients with better guidelines for using chronic exercise training as an approach for the management of cognitive impairment as symptom of MS.
Sandroff, B. M., Diggs, D., Bamman, M. M., Cutter, G. R., Baird, J. F., Jones, D. C., Rinker, J. R., Wylie, G. R. DeLuca, J., & Motl, R. W. (2019).Protocol for a systematically-developed, phase I/II, single-blind randomized controlled trial of treadmill walking exercise training effects on cognition and brain function in persons with multiple sclerosis. Contemporary Clinical Trials, 87
It was previously reported by Sandroff et al (2016) that light, moderate, and vigorous intensity treadmill walking exercise might be appropriate exercise stimuli for inclusion in an exercise training intervention for improving speed-related aspects of inhibitory control. A new study presented by Sandroff et al (2019) aims to investigate some of these topics.
The current study is investigating individuals with MS that are fully ambulatory. These participants will engage in 12 weeks of light to moderate cardiovascular, resistance and stretching exercises three times per week. Participants are tested for cognitive processing speed as well as functional mobility and activities of daily living before and after the 12 weeks of training.
Investigators indicate that this could be the first study to give the first Class I evidence of the effects of treadmill walking as an approach for improving cognitive processing speed and mitigating the impact of slowed reaction time in people who have multiple sclerosis.