Do fatigue and depression have a bivariate association with device-measured physical activity behavior in persons with multiple sclerosis?

This study examined the bivariate association between fatigue and depression symptoms and physical activity behavior in persons with multiple sclerosis (MS).The sample of adults with MS completed the Fatigue Severity Scale (FSS) and the Hospital Anxiety and Depression Scale (HADS) and wore a waist mounted accelerometer during waking hours for 7 days. We categorized participants as having elevated fatigue and depression based on cut-points for the FSS (i.e., 4+ as indicative of severe fatigue) and the HADS (i.e., 8+ as indicative of elevated depressive symptoms). We used a two-way multivariate analysis of variance (MANOVA) to examine the contribution of fatigue and depression to volume and pattern of sedentary, light (LPA) and moderate-to-vigorous physical activity (MVPA).Results indicated no bivariate association between fatigue and depression and measures of physical activity behavior. The MANOVA indicated there was a significant association between fatigue and MVPA (F = 2.30, p = 0.032) and steps/day (F = 13.6, p < 0.001), independent of depression symptoms. There was no association between depression symptoms and physical activity behavior.This study demonstrated an interrelation between fatigue symptoms and MVPA and steps/day in MS, independent of depression symptoms, and this should be considered in the future design and delivery of physical activity interventions in MS.IMPLICATIONS FOR REHABILIATIONFatigue and depression are prevalent and burdensome symptoms of multiple sclerosis (MS).These symptoms can collectively worsen psychological and functional outcomes in MS.Fatigue symptoms may impact ambulatory physical activity to a greater degree than depression symptom status in persons with MS.Fatigue is an important consideration when designing behavior change interventions targeted at promoting physical activity in persons with MS.