ACSM Personal Trainer Certification Practice Exam

Which muscle contributes to hip flexion along with the rectus femoris?

1. Hamstrings

2. Tibialis

3. Iliopsoas

4. Quadriceps

The correct answer is: Iliopsoas

The iliopsoas is the primary muscle that contributes to hip flexion alongside the rectus femoris. The iliopsoas is made up of two muscles: the psoas major and the iliacus. Together, they play a crucial role in lifting the thigh towards the torso, enabling movements such as running, climbing, and kicking. When considering hip flexion, the iliopsoas is particularly significant as it is the strongest hip flexor, generating more force than any other muscle in this action. The rectus femoris, which is part of the quadriceps group, also assists in hip flexion but primarily acts on the knee as an extensor. Hence, while rectus femoris is involved, the iliopsoas is more directly responsible for flexing the hip joint in conjunction with it. Other muscles listed, such as the hamstrings and tibialis, do not significantly contribute to hip flexion, while the quadriceps group, which includes the rectus femoris, mainly facilitates knee extension. Thus, the iliopsoas stands out as the correct answer due to its primary role in hip flexion.