Which term describes the stiffening or resistance to passive stretching of a muscle?

The term that describes the stiffening or resistance to passive stretching of a muscle is contracture. A contracture occurs when a muscle or joint becomes fixed in a shortened position due to prolonged shortening or inactivity, leading to an inability to fully extend the muscle. This can be a result of various factors including prolonged immobilization, chronic pain, or the effects of conditions such as neurological disorders.

In contrast, other terms present different meanings. Spasms refer to sudden, involuntary muscle contractions that may cause pain but are not specifically related to resistance to passive stretching. Tightness is a subjective feeling of muscular tension or rigidity but does not fully capture the persistent condition of limited range of motion associated with contractures. Myopathy denotes a disease or condition of the muscle itself that impairs its function, rather than referring to a loss of flexibility or stiffness in response to stretching. Thus, contracture is the most precise term in describing the stiffness or resistance to passive stretching of a muscle.