AFAA Personal Trainer Certification 2026 – 400 Free Practice Questions to Pass the Exam

The opposing muscles of the hamstrings are indeed the quadriceps. The hamstrings, located at the back of the thigh, are responsible for knee flexion and hip extension. In contrast, the quadriceps are situated at the front of the thigh and play a key role in knee extension.

When engaging in activities that involve bending the knee, such as running or squatting, the hamstrings work in concert with the quadriceps, but they are antagonistic muscle groups. This means that as one group contracts (in this case, the hamstrings), the other must relax or lengthen to allow for smooth and coordinated movement. Understanding this relationship is crucial in designing balanced training programs that ensure both muscle groups are adequately developed to promote joint health, prevent injuries, and enhance athletic performance.

The other choices don't represent opposing muscle groups in this context. The glutes assist the hamstrings in hip extension rather than opposing them. The calves are primarily involved in ankle movement and do not directly oppose the hamstrings. The hip flexors work on the opposite side of the body, helping to lift the thigh forward, but they don't serve as direct antagonists to the hamstrings in terms of knee flexion and extension. Therefore, the quadriceps are the correct