NETA Personal Trainer Practice Exam

The movement characterized by increasing the joint angle is extension. This movement occurs when muscles contract to straighten a joint, resulting in an increase in the angle between the bones that are involved in the joint. For example, when you straighten your arm at the elbow after it has been bent, you are engaging in extension, as the angle between the forearm and the upper arm increases.

In contrast, flexion refers to decreasing the angle at a joint, such as when you bend your elbow. Abduction involves moving a limb away from the midline of the body, while adduction refers to moving a limb towards the midline. Both abduction and adduction primarily involve movements in the frontal plane and do not specifically relate to the increase or decrease of joint angles in the same way that extension and flexion do. Thus, the correct answer focusing on joint angle increase is indeed extension.