Popsugar Health & Fitness Workouts Lower Ab Exercises These Lower Ab Exercises Will Make You So Sore, It'll Hurt to Laugh! 7 March 2018 by Jenny Sugar View On One Page Photo 6 of 23 ADVERTISEMENT () Start Slideshow Share This Link Copy ← Use Arrow Keys → 6 Knee Driver Begin in an elbow plank position with the abs engaged. Draw the left knee into the chest. Then step the foot back to the elbow plank position. Now draw the right knee into the chest and then step it back to the elbow plank position. This counts as one rep. Previous Next Start Slideshow WorkoutsAb Exercises