Objective: To perform a comprehensive evaluation of and identify correlates for physical fitness in consecutive patients with juvenile idiopathic arthritis (JIA) who have been diagnosed in the era of biologics and to compare the results with those obtained in healthy controls.
Methods: The study cohort included 60 patients with JIA (50 girls) ages 10-16 years and 60 age- and sex-matched controls. The JIA group included 30 patients with persistent oligoarticular JIA and 30 patients with extended oligoarticular or polyarticular disease. Measures of physical fitness included cardiorespiratory fitness (CRF) by peak oxygen uptake (Vo2peak ) during a continuous graded treadmill exercise test, muscle strength by isokinetic and isometric knee and hand grip evaluations, and bone mineral density (BMD) and body composition by dual-energy x-ray absorptiometry. Physical activity was assessed by accelerometry.
Results: Forty-two percent of the patients were being treated with biologic drugs. Patients with JIA demonstrated lower muscle strength and total body BMD compared to controls, but there were no differences in CRF and body composition. Physical fitness was comparable between the persistent oligoarticular and extended oligoarticular/polyarticular-JIA groups. In patients with JIA, we identified associations between higher vigorous physical activity and higher CRF and muscle strength, but did not find any association between physical fitness and disease variables.
Conclusion: In this cohort of patients with JIA, we found suboptimal muscle strength and BMD compared to controls, but no differences in CRF and body composition. Vigorous physical activities appeared important for optimizing muscle strength and CRF in patients with JIA; the importance of such activities should be highlighted in patient education.
© 2018, American College of Rheumatology.