Mediating role of physical activity in the relationship between exercise-induced muscle pain and symptom severity in women with fibromyalgia

Background: Individuals with fibromyalgia (FM) exhibit generalized hyperalgesia to pain stimuli, and physical activity (PA) is critical to manage FM symptoms. Purpose: This study examined the relationship between exercise-induced muscle pain, symptom severity, and PA in 28 women with FM. Methods: Muscle pain rating (MPR) was assessed during 3 minutes of submaximal isometric handgrip exercise, whereas PA and symptom severity were evaluated via self-report questionnaires. The analysis examined the relationship between the variables, with the specific interest in the mediating role of PA in the relationship between exercise-induced muscle pain and symptom severity. Results: MPR was positively associated with symptom severity (b = 1.89; 95% CI = 0.01, 3.76; P = .048) and inversely associated with PA levels (b = −0.16; 95% CI = −0.30, −0.03; P = .021). PA levels were inversely associated with symptom severity (b = −7.94; 95% CI = −12.46, −3.42; P = .001). After statistically controlling for PA levels, the relationship between MPR and symptom severity was no longer significant (b = 0.60; Wald 95% CI = −1.05, 2.25; P = .474). Conclusion: Results show the link between the variables, and specifically demonstrate that PA mediates the relationship between exercise-induced muscle pain and symptom severity.