Momentary Reports of Fatigue Predict Physical Activity Level: Wrist, Waist, and Combined Accelerometry

Objective: Fatigue is commonly reported by persons with osteoarthritis (OA) and predicts worse functioning and decreased activity. The current research used a combination of wrist and waist accelerometry along with experience sampling methodology to examine the relationship between reports of fatigue and subsequent physical activity among older adults with knee OA. Method: Two hundred one participants completed an interview followed by a 1-week period during which their activity was monitored and they reported symptoms of pain and fatigue. Multilevel models examined within-subjects versus between-subjects patterns of symptoms and their association with physical activity. Results: Fatigue was the most consistent predictor of lowered physical activity (β = -20.83, p < .001). Although wrist-worn actigraphs produced higher averaged activity counts than did waist actigraphs (t = 34.68, p < .001), multilevel models showed consistent results regardless of placement. Discussion: Fatigue was a consistent predictor of lowered activity regardless of actigraph location.