For a patient with Duchenne muscular dystrophy who is ambulatory but experiencing a decline in strength, which type of exercise is least desirable?

• A. Isometric exercise
• B. Concentric exercise
• C. Muscle setting exercise
• D. Eccentric exercise

Answer: (D)

In Duchenne muscular dystrophy, protecting the muscle from contraction-induced injury is crucial. Eccentric contractions—where the muscle lengthens while producing force—cause higher mechanical stress and greater fiber damage than other types of contraction. In dystrophic muscle, the membrane is fragile without dystrophin, so lengthening under load leads to more sarcolemmal tears, calcium influx, inflammation, and fiber necrosis. That accelerates weakness rather than preserving function, making eccentric loading the most harmful option for someone who is ambulatory but experiencing a decline in strength.

Lower-risk approaches like gentle isometric or concentric exercises, and very light, non-fatiguing muscle-setting activities, can help maintain range of motion and some strength with less risk of additional muscle injury.