Chronic pain is associated with fibromyalgia. Several factors influence pain intensity experienced with fibromyalgia including the number of body pain areas, psychological constructs, and response to peripherally applied stimuli. Thus, in this study the impact of pain and fatigue intensities is a persuasive consideration in the assessment and treatment of fibromyalgia patients.

Fibromyalgia is a condition characterized by chronic widespread muscle pain and fatigue and associated with significant impairment in perceived function and reduced physical performance. The purpose of this study was to determine the degree to which pain and fatigue are associated with perceived function and physical performance in women with fibromyalgia.

Hierarchical linear regression determined the contribution of pain and fatigue (Numeric Rating Scale (NRS) for resting, movement and combined) to perceived function (Fibromyalgia Impact Questionnaire Revised - Function Subscale, FIQR-Function), Multidimensional Assessment of Fatigue - Activities of Daily Living (MAF-ADL) and SF-36 Physical Function Subscale (SF-36-PF) and physical performance (6-Minute Walk Test, 6MWT and Five Time Sit To Stand, 5TSTS) while controlling for age, body mass index, pain catastrophizing, fear of movement, anxiety, and depression in women with fibromyalgia (N = 94).

For perceived function, movement pain and movement fatigue together better predicted FIQR-function (adjusted R2 = 0.42, p ≤ 0.001); MAF-ADL (adjusted R2 = 0.41, p ≤ 0.001); and SF-36-PF function (adjusted R2 = 0.34, p ≤ 0.001). For physical performance measures, movement pain and fatigue together predicted 6MWT distance (adjusted R2 = 0.42, p ≤ 0.001) and movement fatigue alone predicted performance time on the 5TSTS (adjusted R2 = 0.20, p ≤ 0.001).

Pain and fatigue are significantly associated with and explain more than one-third of the variance in perceived function and physical performance in women with fibromyalgia.