Muscle strength, physical fitness and well-being in children and adolescents with juvenile idiopathic arthritis and the effect of an exercise programme: a randomized controlled trial

Background: Decreased muscle strength, fitness and well-being are common in children and adolescents with juvenile idiopathic arthritis (JIA) compared to healthy peers. Biological drugs have improved health in children with JIA, but despite this pain is still a major symptom and bone health is reported as decreased in the group. The improvement made by the biological drugs makes it possible to more demanding exercises. To jump is an exercise that can improve bone heath, fitness and muscle strength. The aim of the study was to see if an exercise programme with jumps had an effect on muscle strength, physical fitness and well-being and how it was tolerated. Methods: Muscle strength and well-being were studied before and after a 12-week exercise programme in 54 children and adolescents with JIA, 9-21 years old. The participants were randomized into an exercise and a control group. Muscle strength, fitness and well-being were documented before and after the training period and at follow-up after 6 months. Physical activity in leisure time was documented in diaries. The fitness/exercise programme was performed at home three times a week and included rope skipping and muscle strength training exercises. Assessment included measurement of muscle strength with a handheld device, and with Grip-it, step-test for fitness with documentation of heart rate and pain perception and two questionnaires (CHAQ, CHQ) on well-being. Results: There were no differences between exercise and control group regarding muscle strength, grip strength, fitness or well-being at base line. Muscle weakness was present in hip extensors, hip abductors and handgrip. For the exercise group muscle strength in hip and knee extensors increased after the 12-week exercise programme and was maintained in knee extensors at follow-up. There was no change in fitness tested with the individually adapted step-test. The CHQ questionnaire showed that pain was common in the exercise group and in the control group. There were only small changes in the CHAQ and CHQ after the training period. The fitness/exercise programme was well tolerated and pain did not increase during the study. Conclusions: A weight bearing exercise programme, with muscle strength training with free weights and rope skipping was well tolerated without negative consequences on pain. It also improved muscle strength in the legs and can be recommended for children and adolescents with JIA.