FNDC5 and fibromyalgia: Evaluation encompassed the assessment of key mitochondrial markers, including PTEN-induced kinase 1 (PINK1), PARKIN, Mitofusion2, cytochrome c oxidase, citrate synthase, and fibronectin type III domain-containing protein 5 (FNDC5), alongside morphological examinations of the gastrocnemius muscle.<h4>Results</h4>Climbing exercise significantly improved fibromyalgia (FM)-like symptoms and enhanced the expression of mitochondrial marker genes in the gastrocnemius muscle.