Popsugar Health & Fitness Plank What Are the Best Side Plank Variations? If You Want to Slim Your Waist, These Are the 13 Best Side Plank Variations 14 March 2018 by Jenny Sugar View On One Page Photo 4 of 13 ADVERTISEMENT () Start Slideshow Share This Link Copy ← Use Arrow Keys → 4 Side Plank Crunch Begin in a side elbow plank with your left forearm on the floor and your right hand behind your head. Keeping your torso stable and your waist lifted, bring your right knee up toward your shoulder to lightly tap your right elbow. Lengthen your right leg back to the starting position to complete one rep. Previous Next Start Slideshow PlankArm ExercisesWorkoutsAb Exercises