Physical Activity Behavior Change Intervention in Persons Newly Diagnosed With Multiple Sclerosis - ActivNMS Trial - COM-B Construct Testing

Multiple sclerosis (MS) is a prevalent neurological disease of the central nervous system that is the leading cause of neurological disability among young adults in the United States. This disease results in the progressive loss of walking, substantial worsening of cognition, symptoms of fatigue, as well as compromised quality of life (QoL). There is evidence that physical activity is beneficially associated with walking mobility, cognitive function, symptoms of fatigue, depression, anxiety, and pain in persons with MS. Nonetheless, this population is strikingly sedentary and physically inactive, including persons newly diagnosed with MS (diagnosed with MS for two years or less). Indeed, approximately 40% of persons with MS reported stopping physical activity after an MS diagnosis, and persons recently diagnosed with MS have not been included in physical activity intervention research. Yet, the early stage of MS represents an ideal time point for initiating physical activity for life-long benefits. There is further evidence that physical activity and exercise interventions delivered remotely can yield benefits in managing MS symptoms and comorbidities, and disability progression. In this study, the investigators aim to primarily test the effect of a 16-week remotely delivered behavioral intervention, compared with a control condition (i.e., waitlist control), on the psychological constructs based on the Capability-Opportunity-Motivation-Behavior model in persons newly diagnosed with MS (disease duration ≤ 2 years). Consequently, this could provide more evidence for the understanding of the intervention mechanism on physical activity behavior in people newly diagnosed with MS. Participants will complete a battery of questionnaires remotely over the internet before and immediately after the 16-week program. The first assessments occur upon enrollment in the study (Baseline Assessment) and the second occurs right after the intervention (16- week Assessment). In this study, participants will be randomly assigned into 1 of 2 conditions: a physical activity condition (receive the intervention immediately after baseline assessment) or a waitlist condition (receive the intervention after the 16-week assessment). Participants in both conditions will receive access to an Internet delivered program for 16 weeks as well as one-on-one coaching through Zoom. The participants could opt in/out of receiving the intervention after the follow-up assessment. The investigators will ask that participants in the physical activity condition wear a Fitbit (this is different from the accelerometer) for tracking physical activity daily during the 16- week period. The investigators will further ask that information from the Fitbit be recorded into a logbook daily.