If you're looking to get a real workout for your abs, look no further than the plank. It's one of the most effective exercises, and the longer you hold, the harder the workout. To figure out how to make the best out of a plank, we asked Andy McDermott, a featured athlete in Muscle & Fitness magazine and owner of Iron Cross Fitness for his favorite variations for a strong core and shredded abs.

!-- Start of Brightcove Player --
!-- By use of this code snippet, I agree to the Brightcove Publisher T and C found at https://accounts.brightcove.com/en/terms-and-conditions/. --

!-- This script tag will cause the Brightcove Players defined above it to be created as soon as the line is read by the browser. If you wish to have the player instantiated only after the rest of the HTML is processed and the page load is complete, remove the line. --!-- End of Brightcove Player --