Which statement best describes the natural history of Duchenne muscular dystrophy regarding strength over time?

• A. Strength remains stable through adolescence
• B. Strength declines after early childhood
• C. Strength increases until age 7 and then declines with a marked drop around age 14
• D. Strength improves after age 14

Answer: (C)

In Duchenne muscular dystrophy, strength follows a particular developmental pattern: early on, as a child grows and develops motor skills, strength can appear to improve or stay relatively preserved. After about age 7, weakness begins to predominate and progresses steadily, with a more rapid decline during adolescence. By around age 12–14, there is a marked drop in strength and many individuals lose the ability to walk.

This reflects the disease process where dystrophin deficiency leads to progressive muscle fiber damage and replacement with fat and connective tissue, primarily affecting proximal leg and hip muscles first, then other muscles. So the statement that strength increases until age 7 and then declines with a notable drop around age 14 best describes the natural history.

The other descriptions don’t fit the typical course: strength isn’t stable through adolescence, there isn’t a simple decline only after early childhood without the initial gain, and strength does not improve after age 14.