What do you call the shrinkage of muscle due to not using it?

What do you call the shrinkage of muscle due to not using it?

• A. Muscle atrophy
• B. Muscle fatigue
• C. Denervation atrophy
• D. Disuse atrophy

Answer: (D)

When a muscle isn’t used for an extended period, its fibers shrink because the body reduces muscle protein synthesis and increases protein breakdown. This specific loss of muscle size from inactivity is called disuse atrophy. It happens with immobilization, casting, bed rest, or spaceflight, where the reduced mechanical load signals the muscles to downsize. Muscle atrophy in general describes loss of muscle mass, but the question points to the cause—not using the muscle—so disuse atrophy is the precise term. Denervation atrophy would come from a loss of nerve supply to the muscle, not just lack of use, and muscle fatigue is a temporary decline in performance from metabolic factors, not structural shrinking.

When a muscle isn’t used for an extended period, its fibers shrink because the body reduces muscle protein synthesis and increases protein breakdown. This specific loss of muscle size from inactivity is called disuse atrophy. It happens with immobilization, casting, bed rest, or spaceflight, where the reduced mechanical load signals the muscles to downsize.

Muscle atrophy in general describes loss of muscle mass, but the question points to the cause—not using the muscle—so disuse atrophy is the precise term. Denervation atrophy would come from a loss of nerve supply to the muscle, not just lack of use, and muscle fatigue is a temporary decline in performance from metabolic factors, not structural shrinking.