ACSM Personal Trainer Certification Practice Exam

What is the relationship between flexion and extension in joint movement?

1. Flexion increases joint angle; extension decreases joint angle

2. Flexion and extension both increase joint angle

3. Flexion decreases joint angle; extension increases joint angle

4. Flexion and extension are synonymous movements

The correct answer is: Flexion decreases joint angle; extension increases joint angle

Flexion and extension are fundamental movements that occur at various joints in the body, particularly at the hinge joints like the knee and elbow. When a joint undergoes flexion, the angle between the two bones decreases, bringing them closer together. This is seen, for example, when bending the elbow or knee. Conversely, during extension, the angle increases as the bones move farther apart from each other, such as when straightening an arm or leg. Therefore, the correct understanding of flexion and extension is that flexion leads to a decrease in the joint angle, while extension results in an increase in the joint angle. This distinction is essential for personal trainers and fitness professionals as they instruct clients on proper movement patterns and exercise techniques. Recognizing these movements also helps in identifying muscular involvement during various exercises, injury prevention, and rehabilitation strategies.