Ab Wheel Exercises
Conquered the Plank? Try the Ab Wheel — These 4 Exercises Will Make Your Whole Body Shake
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For this ab wheel variation, which takes a step up in difficulty, you'll simply elevate your knees on a raised surface, such as a mat. "This increases the range of motion of the ab wheel rollout and in return, creates a more challenging position to stabilize and resist extension," Eric and Ryan told POPSUGAR.