AFAA Personal Trainer Certification 2025 – 400 Free Practice Questions to Pass the Exam

The quadriceps muscle group is primarily responsible for knee extension. This muscle group consists of four muscles located at the front of the thigh: the rectus femoris, vastus lateralis, vastus medialis, and vastus intermedius. When activated, these muscles work together to extend the knee joint, which is a crucial movement in various activities such as walking, running, jumping, and squatting.

While other muscle groups and anatomical structures also contribute to movements at the knee and other joint areas, the quadriceps are distinctly recognized for their role in extending the knee. Knee flexion, mentioned as one of the other options, is primarily performed by the hamstrings, which are located on the back of the thigh. Hip extension is mainly the function of muscles like the gluteus maximus and hamstrings, while ankle inversion involves muscles that are not related to the quadriceps at all. Understanding the specific functions of muscle groups is vital for effectively designing training programs and ensuring proper movement techniques.