Popsugar Health & Fitness Workouts Best Crunch Variations Add These 20 Crunch Variations to Your Routine and Chiseled Abs Are on Their Way! 5 August 2018 by Jenny Sugar View On One Page Photo 9 of 20 ADVERTISEMENT () Start Slideshow Share This Link Copy ← Use Arrow Keys → 9 Runner's Crunch Start on your back with your elbows resting on the floor at a 90-degree angle. With your core engaged, roll up to almost sitting while bringing your right knee up to meet your left elbow. It should feel a little like running. With control, straighten your leg as you slowly lean your back down, vertebra by vertebra, until your shoulders touch the mat last. Alternate with your other leg to complete one rep. Previous Next Start Slideshow WorkoutsAb Exercises