What does extension refer to in joint movement?

Extension refers to the movement of a joint that increases the angle between the body parts that meet at the joint. When a joint is extended, it moves from a flexed position (where the joint is bent and the angle is smaller) back to a straight position, effectively straightening the limb or body part involved. This action is essential in various movements, from straightening the arm after a curl to kicking a leg forward.

Understanding extension is crucial in fields like sports medicine, as it helps in assessing joint health, designing rehabilitation exercises, and improving athletic performance. The other options describe different movements: bending refers to flexion, rotation describes a different axis of movement, and muscle flexing relates to muscle contraction rather than joint movement.