The objectives of this study are to study the effect of formal exercise training on motor function and overall physical fitness in children with arthritis. A 12-week comprehensive exercise program will be used. Formal exercise training will be compared to Qi gong.

Childhood arthritis is a common and often debilitating disease. Children with arthritis are less active than their peers, and consequently they often have poor physical fitness. This study follows up our pilot study, in which we showed that exercise training can be safely carried out in children who have arthritis.

We plan to randomly assign 80 children with arthritis to one of two groups. The experimental group undergoes a vigorous exercise training program consisting of twelve weekly supervised sessions as well as twice weekly at home sessions using an exercise video. The control group also has twelve supervised sessions and two home sessions. However, their exercises are non-strenuous, based on Qi gong. All children have comprehensive fitness testing before and after the training at the exercise lab at the Hospital for Sick Children.

If we show that fitness exercise leads to improved motor function and improved ability to carry out activities of daily living, then we will change the way in which we provide therapy for childhood arthritis. We hope that this study will lead to an improved quality of life for children with arthritis.

Inclusion Criteria:

1. Age 8 - 16 years.
2. Diagnosis of Juvenile Idiopathic Arthritis - based on the revised Durban criteria.
3. Polyarticular or pauciarticular course.
4. Stable Disease - on a stable dose of NSAID, and if applicable methotrexate or other second line agents - in the preceding month, and judged by the attending rheumatologist to be clinically stable and unlikely to need a change in medication over the course of the trial.
5. Medications. There are no restrictions on medication use for this study; however, every effort is made to keep medication dosage stable over the course of study.

Exclusion Criteria:

1. Co-morbidity with cardiac, pulmonary or metabolic disease.
2. Moderate or severe hip pain while walking (as judged by the patient and scored on a 4 point scale) or active systemic symptoms (fever, rash).
3. Children who engage in more than 3 hours of structured extracurricular physical activity weekly may not show additional gains from fitness training and, therefore, are not studied. Children are not otherwise excluded from the study if currently attending a physiotherapy pool program with emphasis on joint range of motion and stretching.
4. Children who are unable to cooperate with testing procedures.