Fibromyalgia is a disabling condition affecting 2–4% of the global population, mostly in females. Resistance exercise has been increasingly recommended as part of non-pharmacological management for persons with fibromyalgia. However, the optimal dose remains unclear.

To determine the overall effect of resistance exercise on pain intensity using the Fibromyalgia Impact Questionnaire (FIQ) among individuals with fibromyalgia, and to explore resistance exercise dose parameters associated with clinically meaningful improvements, and to assess dose-response associations between resistance exercise and these outcomes.

Following PRISMA guidelines, randomized controlled trials (RCTs) were identified in PubMed, Web of Science, PEDro, and Scopus up to July 2025. Studies were selected according to PICOs criteria if they involved participants diagnosed with fibromyalgia, reported pain, or FIQ scores, following a resistance exercise intervention. The mean difference (MD) with 95% confidence intervals (CI) was calculated. Exercise prescription characteristics were examined using subgroup analysis, whereas dose-response associations were explored through meta-regression.

Fourteen RCTs, including 871 participants (all females), met the inclusion criteria. Resistance exercise significantly reduced pain intensity (MD -0.83, 95% CI -1.50 to -0.19; P = 0.003) and disease impact (MD -8.78, 95% CI -13.39 to -4.18; P < 0.001) compared with other interventions or control groups. Subgroup analyses suggested that clinically relevant improvements were observed in programs performed 2 to 3 times per week, using progressive approaches and external resistance, including free weights, machines, or elastic bands. Meta-regression analyses suggested that higher exercise intensity, greater weekly volume, and interventions lasting approximately 12 weeks were associated with larger improvements in pain and FIQ scores.

Resistance exercise may be an effective strategy for reducing pain intensity and the impact of the disease in fibromyalgia when appropriately prescribed and progressed over time. Exercise programs should be individualized, emphasizing personal preferences to maximize long-term adherence and benefits.