Stair-climbing resistance exercise, with or without oral turmeric (Curcuma longa L.) supplementation, relieves symptoms and promotes musculoskeletal repair in experimental rheumatoid arthritis in rats

Rheumatoid arthritis is a chronic systemic inflammatory disease associated with joint inflammation, skeletal muscle dysfunction, and reduced physical capacity, reinforcing the need for complementary non-pharmacological strategies aimed at preserving musculoskeletal function. This study investigated the functional and morphological effects of turmeric supplementation associated with stair-climbing resistance exercise in Wistar rats with adjuvant-induced arthritis (AIA), an experimental model representative of rheumatoid arthritis. Thirty-one Wistar rats were randomly allocated into five groups: control (CTRL, n = 6), adjuvant-induced arthritis (AIA, n = 6), AIA treated with turmeric (AIA + T, n = 6), AIA subjected to stair-climbing resistance exercise (AIA + E, n = 6), and AIA treated with turmeric combined with exercise (AIA + T+E, n = 7). Arthritis was induced using Complete Freund’s Adjuvant. Functional outcomes included joint swelling and hindlimb grip strength. On Day 23, animals were euthanized, and analyses of muscle fibers, connective tissue, and neuromuscular junctions were performed. AIA induced joint swelling and reduced muscle strength. Histological analyses revealed muscle fiber alterations characterized by fiber size variability, centrally located nuclei, and mononuclear inflammatory infiltration. These alterations were less pronounced in exercise-treated groups. Stair-climbing resistance exercise improved functional performance and preserved muscle morphology, whereas turmeric supplementation alone produced limited functional effects. Neuromuscular junction morphometry showed an increase in smaller diameter in arthritic animals that was attenuated by exercise. Stair-climbing resistance exercise attenuated functional and morphological impairments associated with adjuvant-induced arthritis, supporting its role as a complementary therapeutic strategy. Turmeric supplementation alone showed limited effects under the conditions tested and warrants further investigation.