Popsugar Fitness Body Weight 32 No-Equipment Ab Exercises You Can Do on a Mat Heat Up Your Core With 32 Small-Space, On-the-Floor Ab Moves You Can Do Right on Your Mat 31 March, 2020 by Maggie Ryan View On One Page Photo 24 of 32 ADVERTISEMENT () Start Slideshow Share This Link Copy ← Use Arrow Keys → 24 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 Body WeightBodyweight ExercisesCore ExercisesAb ExercisesWorkouts