What defines a first degree strain?

A first degree strain is defined by minor damage to the muscle or tendon, typically involving the stretching of these tissues without any significant tearing. This condition is characterized by mild symptoms such as slight pain, minimal swelling, and tenderness at the site of the injury. Since the muscle fibers are only overstretched, the ability to use the muscle is generally maintained, with some discomfort during movement.

In contrast, options that describe a complete muscle tear, severe pain and swelling, or limited range of motion typically relate to more serious injuries classified as second or third degree strains. These latter injuries involve greater tissue damage, leading to more intense symptoms and functional impairments. Therefore, the defining characteristic of a first degree strain lies in its mild nature, primarily manifesting as a stretch with slight pain, making the correct choice a reflection of the least severe form of muscle strain.