Acute Effects of Walking Exercise on Brain Functioning in Multiple Sclerosis

The project will involve a within-subjects, repeated-measures research design. Participants will initially be screened for relevant inclusion/exclusion criteria for maximizing safety of participating in an exercise study. If a participant meets those inclusion/exclusion criteria, they will visit Kessler Foundation three times. The first visit will involve a baseline session where participants will complete several cognitive tests. This will be followed by a training session, where participants will be provided with a FitBit, and will be trained by research staff to walk at a rate of 100 steps per minute. Once participants demonstrate proficiency at walking at this rate using the FitBit, participants will complete several questionnaires, followed by a maximal, graded exercise test to determine cardiorespiratory fitness. One week later, participants will return to Kessler Foundation to complete 1 of 2 experimental sessions that will be delivered in a random order that further will be counterbalanced across participants (to minimize the potential effects of session order on brain function and blood flow, respectively). Both experimental sessions will follow the same structure. First, participants will undertake a 30-minute MRI scan at Kessler Foundation to measure brain function and brain blood flow. Immediately following the MRI scan, participants will engage in either 20 minutes of treadmill walking exercise or 20 minutes of overground walking exercise at a rate of 100 steps per minute. Immediately following the 20-minute exercise bouts, participants will undertake another MRI scan for measuring brain function and brain blood flow. Participants will return to Kessler Foundation a third time to complete the opposite experimental session that was not completed during the second visit (i.e., overground walking exercise if treadmill walking exercise was completed during the second visit). In total, each participant will undergo four MRI scans over the course of the study (i.e., pre-treadmill, post-treadmill, pre-overground, post-overground). .