And along the way, you’ll build those six-pack abs, too. HOW TO DO IT: An underrated plank upgrade, this move challenges your abs and obliques (and your glutes, too!). Start in pushup position ...

explains what you'll really need to show off those six-pack abs. Produced by Kevin Reilly. Additional camera by Grace Raver and Will Wei. Special thanks to Michael Bultman and CrossFit NYC.

Follow these 4 simple rules on how to work your lower abs. Don't get stuck with a 4 pack abs, instead work on getting the full washboard. Want core strength, six-pack abs, and a healthy spine?