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 8 of 13 ADVERTISEMENT () Start Slideshow Share This Link Copy ← Use Arrow Keys → 8 Sassy Side Plank Lie on your left side with the knees slightly bent and your elbow underneath your shoulder. Press into your bottom forearm to lift the hips as high as you can, keeping the abs engaged. Raise your top knee to open the thighs like butterfly wings, then slowly lower the knee, completing one rep. The move is similar to the clam. Previous Next Start Slideshow PlankArm ExercisesWorkoutsAb Exercises