Daily Temporal Associations Between Physical Activity and Symptoms in Multiple Sclerosis

Background Symptom severity is negatively associated with physical activity in multiple sclerosis (MS). However, it is unclear how physical activity and symptoms correlate on a day-to-day basis in persons with MS. Purpose To determine the temporal within-person associations of pain, fatigue, depressed mood, and perceived cognitive function with physical activity in MS. Methods Ambulatory adults with MS (N = 107) completed 7 days of home monitoring. Continuous physical activity data (assessed via wrist-worn accelerometer) and concurrent ecological momentary assessment (5X/day) of pain, fatigue, depressed mood, and perceived cognitive function were collected. Data were analyzed using multilevel mixed modeling. Results Fatigue and depressed mood demonstrated bidirectional associations with physical activity, whereas pain and cognitive function did not. Higher than usual fatigue (B = -5.83, p = .001) and depressed mood (B = -4.12, p = .03) were followed by decreased physical activity. In contrast, higher than usual physical activity was associated with subsequent decline in fatigue (B = -0.001, p = .02) and depressed mood (B = -0.0007, p = .02); however, the association between physical activity and fatigue varied across the day. Conclusions Physical activity is dynamically related to fatigue and mood on a moment-to-moment basis in MS. Efforts to increase physical activity in MS must incorporate a focus on how symptoms affect and are affected by activity.