Physical Exercise as a Targeted Therapy in Patients With Chronic Rheumatic Muscle Inflammation

Inclusion Criteria: * Patients with chronic, stable polymyositis or dermatomyositis with diagnosis of definite or probable polymyositis or dermatomyositis (Bohan and Peter 1975) * Age 18-80 years * Duration since diagnosis \> 6 months * Exercising \< once a week, * Stable disease activity and medication for at least one month. Ten healthy controls matched for age, gender and physical exercise level will be included. \- Exclusion Criteria: * Severe pulmonary fibrosis * Heart or lung conditions that contraindicate vigorous exercise * Severe osteoporosis * Not being able to perform the exercise program.