This exercise named after Physical Therapist John Pallof, has become one of my favorite core exercises. Why I feel this exercise has such value is because it can be done in several positions depending on your dysfunction. Whether you are standing, 1/2 kneeling, or tall kneeling, this exercise can also be used as a movement test to detect any left/right asymmetries. As I wrote previously in other posts, the core is more than just abdominals. The Pallof Press calls upon the entire core (lumbo-pelvic hip complex) to execute properly. The hips are key stabilizers in this exercise as well, which you will feel once you add some weight and hold the lower body static. Are you having problems creating stability in the lunge position, try half kneeling. Or maybe stability is an issue during squatting or deadlifting, than the tall kneeling/standing position fits you best. Remember the more joints you need to stabilize, the more difficult the exercise. That is why in most situations I have my clients start in the tall kneeling position and progress from there once it has been mastered. Make sure before you add weight that you are able to hold a perfect starting position with a tall posture and stationary lower body. Once you add weight and lock the hips in place, the resistance on the cable is going to want to pull the trunk into rotation. If the core is holding strong, we can prevent these forces and hold static. Here are a few videos to demonstrate.