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

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. 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. Fatigue was the most consistent predictor of lowered physical activity (β = -20.83, < .001). Although wrist-worn actigraphs produced higher averaged activity counts than did waist actigraphs ( = 34.68, < .001), multilevel models showed consistent results regardless of placement. Fatigue was a consistent predictor of lowered activity regardless of actigraph location.