The association between daily physical exercise and pain among women with fibromyalgia: the moderating role of pain catastrophizing

INTRODUCTION: Fibromyalgia (FM) is a condition marked by widespread chronic pain and an array of somatic and psychological symptoms. The primary objective of this study was to explore daily associations between physical activity and pain intensity among a sample of women with FM and the potential moderation of this association by pain catastrophizing. METHODS: Women with FM (N = 107) completed questionnaires assessing pain, FM symptoms, and psychological measures and were then asked to report their levels of daily pain catastrophizing, physical activity, and pain intensity once per day for a period of 1 week using daily electronic diary-based tracking. In addition, objective measures of physical activity were collected using an activity tracker (Fitbit Flex), which measured step counts. Daily self-report physical activity was used as the independent variable and pain intensity (Brief Pain Inventory) was the outcome, whereas daily pain catastrophizing was tested in the model as the potential moderator. RESULTS: Moderation analyses demonstrated associations between physical activity and pain intensity, which were moderated by patient's level of catastrophizing (B = 0.003, SE = 0.001, P < 0.05), with patients scoring higher in daily catastrophizing showing a relatively stronger link between higher day-to-day physical activity and increased daily FM pain. Significant associations were observed between pain catastrophizing, pain intensity, and Fitbit Flex step count (P < 0.05). CONCLUSIONS: Our findings suggest that increases in daily physical activity is associated with more self-reported pain intensity in women with FM pain, particularly among those with higher levels of pain catastrophizing.