Fibromyalgia is a chronic condition of unknown cause, characterized by widespread pain sensitivity and fatigue. After the updates in the criteria for the diagnosis of sarcopenia, carried out by the European Working Group on Sarcopenia in the Elderly (EWGSOP2), muscle strength reduction has become the main parameter for investigating this condition. In this context, there is a lack of information in the literature about the occurrence of sarcopenia in women with fibromyalgia, considering this new criterion.

To evaluate and compare functional capacity and occurrence of sarcopenia in adult women with and without fibromyalgia.

This is a cross-sectional study carried out at the Integrated School Clinic of the Integrated Institute of Health of the Federal University of Mato Grosso do Sul (CEI/INISA/UFMS). The sample was composed by 38 women aged between 20 and 50 years (with index body mass (BMI) <30kg/m2, non-pregnant or puerperal women, non-menopausal and without the presence of another rheumatological condition), divided into two groups, fibromyalgia (GF; n=19) and control (GC; n=19), and matched by age. All participants were evaluated for muscle strength using the five-repetition Sitting and Standing Test (5STS), appendicular muscle mass using bioimpedance analysis (BIA), and physical performance using the Timed Up and Go Test (TUG Test). Subsequently, the participants were evaluated for the presence and degree of sarcopenia (pre-sarcopenia, sarcopenia, severe sarcopenia), following the criteria and cutoff points for muscle strength, muscle mass, and physical performance proposed by the EWGSOP2. Statistical analysis: Student's t-test for independent samples and Chi-square test, significance level of 5%.

Women with fibromyalgia had worse results for 5STS (GF 16.7±5.5; GC 10.3±3 s, p<0.001) and TUG TEST (GF 8.7±2.4; GC 6.3±0.6 s, p<0.001) compared to healthy women. There was no statistical difference between groups regarding appendicular skeletal muscle mass (GF 22.9±2.8; GC 22.9±2.6 kg/m2, p=0.981). Pre-sarcopenia occurrence was higher in GF than in GC (GF 57.9%; GC 5.3%, p<0.001). There was no occurrence of sarcopenia and severe sarcopenia in either group.

The occurrence of pre-sarcopenia is higher in adult women with fibromyalgia when compared to women without fibromyalgia. In addition, women with fibromyalgia have lower muscle strength and worse physical performance than women without fibromyalgia, but without a reduction in muscle mass.

It is important to monitor muscle function (muscle strength and physical performance) in individuals with fibromyalgia, even in the absence of muscle mass reduction, to develop health intervention strategies that attenuate or prevent sarcopenia.