Objective: To compare muscle strength (MS), fatigue, functional capacity, and proprioceptive acuity in patients with fibromyalgia (FM) and controls, to evaluate the impact of FM severity on these features.

Materials and Methods: Sixty women with FM and 45 healthy controls were included. FM-related measurements (number of tender points, myalgic score, pain visual analogue scale (VAS), fibromyalgia impact questionnaire (FIQ)) of the patients were recorded. The patients were classified as having moderate and severe FM assessed by the FIQ. All participants underwent following assessments: knee flexor-extensor muscles strength, handgrip strength, proprioceptive acuity, 6-minute walk test (6MWT), and the multidimensionalassessment of fatigue scale (MAF).

Results: Knee flexor-extensor muscles strength, and 6MWT were significantly lower, MAF score was significantly higher in FM patients than in controls (p<0.05). There were no significant differences between the patients and controls in terms of proprioceptive acuity and handgrip strength (p>0.05). Pain VAS and MAF scores were significantly higher in patients with severe FM compared with those with moderate FM (p<0.05). In patients, knee flexor-extensor muscles strength and handgrip strength were not associated with pain VAS and MAF scores, 6MWT, and proprioceptive acuity (p>0.05). 6MWT was negatively associated with pain VAS score (p=0.001). MAF score was positively associated with pain VAS score (p<0.05), but it was not associated with 6MWT (p>0.05).

Conclusion: The patients had increased fatigue and pain intensity, reduced  knee flexor-extensor muscle strength and functional capacity compared to the healthy subjects. Pain intensity and fatigue were found to be more affected by FM severity. According to these results, improving function and MS should be taken into consideration in the management of FM, but releiving pain and improving fatigue should be prioritised.