Start: Position the end of the bench 2 ½ to 3 feet from the low pulley. Use an aerobics step, a wooden box, weight plate, sandbags, phone books, or other sturdy platform to raise the far end of the bench so it slants down toward the pulley. Attach the ankle straps to your ankles, then hook both straps to the pulley. Lie facedown on the bench with your head at that high end of your knees hanging off the low end.
Finish: Curl your heels as close as possible toward your rear end. Pause, then slowly return to the starting position. Keep your hips and front thigh flat on the bench throughout.