Objective: We evaluated the effectiveness of strengthening exercises using the Swiss ball in patients with fibromyalgia (FM).

Material and Method: Sixty FM patients were randomized into two groups: an intervention group (IG), in which patients performed muscle strength exercises using the Swiss ball, and a stretching group (SG), in which patients performed stretching exercises. All patients participated in 40-minute training sessions three times per week for 12 weeks. The IG performed the following eight strengthening exercises using a Swiss ball: lateral rise, simultaneous biceps curl, squat, two arms triceps extension, abdominal, one arm dumbbell row, reverse crucifix and crucifix. The SG performed exercises targeting the same muscle groups trained in IG. Outcome measures were as follows: visual analogue scale (VAS) for pain, 1 repetition maximum test for muscle strength; fibromyalgia impact questionnaire (FIQ) to evaluate disease impact, and short form health survey (SF-36) to assess quality of life. All participants underwent an evaluation at baseline, at 6 weeks and at 12 weeks of training. The assessor was blind to patient allocation.

Inclusion Criteria:

• female with fibromyalgia according to the classification criteria of the American College of Rheumatology;
• aged between 20 and 65 years old.

Exclusion Criteria:

• uncontrolled hypertension;
• decompensated cardiac disease;
• history of syncope or exercise-induced arrhythmias and decompensated diabetes;
• severe psychiatric illness;
• history of regular exercise at least twice a week for the last 6 months;
• any other condition that could prevent the patient from performing physical exercises.