SETUP: Lie flat on the ground and grip a Swiss ball between your ankles. Keep a slight bend in your knees at all times.
REP: Squeeze your abs to draw the ball up towards your chest, ensuring your butt gets off the floor at the peak of the rep. Stay in control as you lower the ball back down to the ground.
TIP: Getting your butt off the ground is the key to success with this move. It’ll ensure you go beyond the typical 90 degree angle most people do, which forces the abs to become the primary drivers in the exercise (the hip flexors assist a LOT with the first half of the rep!).