Efficacy of accommodating variable-resistance training on muscle architecture, peak torque, and functional performance in patients with juvenile idiopathic arthritis: A randomized controlled trial.

PURPOSE: This study sought to find out if a 6-week accommodating variable-resistance (AcVR) training might enhance muscle architecture, peak torque, and functional performance in patients with juvenile idiopathic arthritis (Juv-IA).

METHODS: Fifty-eight patients with polyarticular Juv-IA (aged 12-18 years) were involved in a randomized controlled trial. They were allocated into two groups: the AcVR group ( n  = 29; underwent AcVR training, and the control group ( n  = 29; received the usual exercise regimen). Interventions were applied three times a week over six consecutive weeks. Measurements were done at baseline and after the intervention. The primary outcome measures were muscle architecture and peak torque, with functional capacity being the secondary measure.

RESULTS: Compared to the control group, the AcVR group showed favorable pre-to-post changes in muscle architecture [fascicle length ( P  = 0.0007, η 2 p  = .18), pennation angle ( P  = 0.0004, η 2 p  = .20), and muscle thickness ( P  = 0.001, η 2 p  = .17)]. Further, the AcVR group revealed a greater increase in peak concentric torque of knee extensors at angular speeds of 120°/sec [right side ( P  = 0.0032, η 2 p  = .08); left side ( P  = 0.039, η 2 p  = .07)] and 180°/sec [right side ( P  = 0.01, η 2 p  = .11); left side ( P  = 0.014, η 2 p  = .10)]. Furthermore, The AcVR group achieved more conducive changes in functional performance [6-min walk test ( P  = 0.003, η 2 p  = .15), timed up and down stair test ( P  = 0.009, η 2 p  = .12), and 4 × 10 m shuttle run test ( P  = 0.036, η 2 p  = .08)].

CONCLUSION: A 6-week AcVR training is potentially effective for improving muscle architectural qualities, enhancing peak muscle torque, and boosting functional performance in patients with Juv-IA without experiencing any detrimental side effects.