ACE Personal Trainer Practice Exam

In which movement do muscles work to increase the angle between two bones?

1. Flexion

2. Extension

3. Adduction

4. Pronation

The correct answer is: Extension

The movement in which muscles work to increase the angle between two bones is known as extension. This occurs in various parts of the body and is often observed when a joint straightens out, resulting in a greater distance between the two bones that form the joint. For example, when you straighten your arm at the elbow, the angle at the joint increases, illustrating extension. In contrast, flexion is the movement that decreases the angle between two bones, such as bending the arm or leg. Adduction refers to the movement of a limb toward the body's midline, while pronation involves the rotation of the forearm or foot that causes the palm to face downward or backward. Understanding these definitions is crucial, as it helps in identifying and describing different types of body movements in various fitness and anatomical contexts.