Eight patients with polymyositis or dermatomyositis according to the Bohan and Peter criteria and who had all participated in a resistive exercise trial at Karolinska University Hospital, Stockholm, Sweden, were included in this study. Patients were included if they had a disease duration more than 12 months and they had to have a stable, low disease activity and medication for three months before enrollment in the study. Patients with inclusion body myositis were excluded as well as patients with co morbidities that contradicted vigorous exercise (severe osteoporosis with multiple fractures, malignant disease severe lung disease) or if they were physically active more than once a week. The median disease duration at time of study start was 4.5 years (range 2,7-29 year). All patients had been treated with glucocorticoids and other immunosuppressive therapies with some improvement of muscle function but with persisting muscle impairment. At time of study seven patients were still on immunosuppressive treatment, five were taking prednisone with a median dosage of 2.5 mg/day (range 0-6.25 mg/d). Six patients were treated with azathioprine, one in combination with cyclosporine A, one patient was treated with methotrexate and one with IVIG 2g/kg body weight every three months