Do It: Lie faceup on the floor, arms out to the sides, lower legs on a stability ball. Push your hips up until your body forms a straight line from shoulders to knees, then pull your heels toward you and roll the ball as close as possible to your butt. Pause, then roll the ball back until your body is in a straight line again. Lower your hips back to the floor. That’s one rep.
Strong hamstrings are just as crucial as strong glutes to get the backside of your dreams.