Great #ab workout that you can do in 10 minutes. #core #sixpack #crunch #plank #crossfit #BodPod #bodyfat__

The plank strengthens the dozens of muscles between your shoulders and hips. But if you jack your feet in and out as you do it, the plank suddenly becomes so much more than just a core builder. The quick movement of your feet provides a great dynamic stability challenge that makes your abs scream, a…

http://www.menshealth.com/fitness/plank-jack?cid=soc_MensHealthMag_TWITTER_Men%27s+Health__