Which of the following is NOT considered a musculoskeletal disorder?

Cardiomyopathy is not considered a musculoskeletal disorder because it specifically refers to a disease of the heart muscle, which affects the heart's ability to pump blood effectively. This condition is primarily a cardiovascular issue, distinct from musculoskeletal disorders that involve the muscles, bones, and connective tissues.

In contrast, osteoporosis, osteoarthritis, and sarcopenia are all classified as musculoskeletal disorders. Osteoporosis is characterized by decreased bone density and increased fracture risk, osteoarthritis involves the degeneration of joint cartilage and underlying bone, and sarcopenia refers to the loss of muscle mass and strength that occurs with aging. These conditions directly relate to the musculoskeletal system, highlighting the significance of muscle and bone health in overall physical function.