Isometric exercise increases strength and does not produce sustained creatinine phosphokinase increases in a patient with polymyositis.

A patient with active stable idiopathic polymyositis received a 4-week supervised right quadriceps and biceps isometric strengthening program. He demonstrated a significant increase in isometric peak torque without a sustained rise in creatinine phosphokinase (CPK). A significant decrease in postexercise CPK occurred at the end of the exercise program. We conclude a randomized clinical trial using a nonexercised patient group vs an exercised patient group may be useful.