Effect on maximal strength of submaximal exercise in Duchenne muscular dystrophy

Four Duchenne muscular dystrophy patients, with quadriceps of at least antigravity strength, exercised one quadriceps submaximally 4 or 5 days per week for six months. The exercise was done under supervision and consisted of extending one knee from 90 degrees to full extension using the Cybex isokinetic exerciser. The other side was not exercised at all. The two sides were tested for maximal isokinetic strength monthly for twelve months and at 18 and 24 months after the beginning of the study. On the average, the exercised leg had a greater maximal torque both during and after the exercise period until the torques on both sides decreased to zero. The results indicate that submaximal exercise has no negative effect and may be of limited value in increasing strength in Duchenne muscular dystrophy.