Sit on the end of a bench with your legs fully extended out in front of you in the air. Lean your torso back and grip each side of the bench firmly with your hands. Keep your core braced and a neutral spine. This is your start position. Proceed to lift your torso away from the bench whilst simultaneously bringing your knees to your chest. Hold for a moment at the top, squeezing your core. With control, return to the start position. Repeat for the required number of reps (or time).