What is the characteristic of muscle that enables it to shorten and thicken during contraction?

The ability of muscle to shorten and thicken during contraction is known as contractility. This characteristic reflects the muscle's capacity to generate force and perform work. When a muscle contracts, its fibers slide together, creating tension and reducing the length of the muscle. This is fundamental to how muscles create movement in the body, allowing for activities like walking, running, and swimming.

Other characteristics of muscle, such as elasticity, extensibility, and plasticity, play different roles in muscle function. Elasticity refers to a muscle's ability to return to its original shape after being stretched or contracted. Extensibility is the ability of muscle to stretch without damage. Plasticity refers to the muscle's ability to change in response to prolonged changes in conditions or use. While these characteristics are important for overall muscle function and adaptability, they do not specifically describe the process of muscle contraction like contractility does.