Match the following exercise to the muscle it primarily targets: Ab Prep.

Ab Prep primarily targets the internal oblique muscles. This exercise involves a curling motion that focuses on flexing the spine, which is essential for engaging the abdominal muscles effectively. The internal obliques play a critical role in trunk rotation and stabilization, which are vital components during the Ab Prep movement. By aligning the movement with the engagement of these muscles, practitioners can develop greater strength and control in their core, contributing to better overall stability and functional movement patterns.

The other muscles listed have different functions: the glutes are more involved in hip extension and stabilization, the hip flexors are primarily responsible for lifting the thigh towards the abdomen, and the erector spinae plays a role in extending the spine rather than flexing it. Therefore, the correct association of Ab Prep with the internal obliques highlights the focus on core strengthening and spinal flexion involved in this exercise.