Start in a plank with your feet on the wheel, hands planted on the floor under your shoulders. Keeping your legs mostly straight, pike your hips up toward the ceiling by rolling the wheel in toward your hands, so your body folds into an upside-down V. Your hands stay planted the whole time — all the movement happens at your hips as the wheel rolls. Reverse it slowly back to the plank rather than letting your hips drop and the wheel shoot forward out of control. Keeping your shoulders stacked over your hands through the range keeps tension on your core instead of your lower back.