HOW: For this exercise get set up in a sidelying position with your top foot resting on the box and your elbow resting comfortably under your shoulder. Once in the copenhagen plank position, reach back with your bottom foot and reach forward with your top arm. Once in the fully extended position, bring the top arm back and drive the extended knee up towards your chest.
FEEL: You should feel your groin muscle working as well as the muscles of your shoulder and core as you perform this multidirectional exercise.
COMPENSATION: Keep your hips elevated for the entirety of this exercise, do not let them sag down toward the ground.