Which change describes immobility's impact on the musculoskeletal system?

• A. Joint hypermobility
• B. Muscle hypertrophy
• C. Reduction in muscle mass and atrophy
• D. Increased bone mineral density

Answer: (C)

When movement is limited, muscles undergo disuse atrophy. Lack of regular use sends signals that reduce protein synthesis and increase protein breakdown, causing muscle fibers to shrink and overall muscle mass to decline. This loss of mass leads to weakness and reduced functional ability, which is the most typical musculoskeletal change with immobility.

Other choices don’t fit as well because joint laxity isn’t caused by staying still and can actually become more limited (stiffness or contractures may develop with prolonged immobility). Muscle hypertrophy requires increased loading and activity, not inactivity. Increased bone mineral density would come from weight-bearing activity, whereas immobility often leads to bone loss due to unloading. Interventions like early mobilization, ROM and strengthening exercises as tolerated, and good nutrition help counter these effects.