What condition results from prolonged immobilization leading to loss of muscle mass and strength?

• A. Osteoporosis
• B. Tendinopathy
• C. Muscle hypertrophy
• D. Disuse atrophy

Answer: (D)

Prolonged inactivity causes muscle tissue to shrink and weaken. When a muscle or limb is immobilized, the mechanical load on the fibers drops, leading to a decrease in muscle protein synthesis and an increase in protein breakdown. Over time, the muscle fibers atrophy, reducing both mass and strength. This specific process is known as disuse atrophy.

Osteoporosis involves loss of bone density rather than muscle, tendinopathy is a tendon condition from overuse or degeneration, and muscle hypertrophy is an increase in muscle size from training or overload. These scenarios don’t match the situation of loss of muscle mass and strength due to immobilization.