This workout hits you right at the core. With 4 different core moves and no rest, you will build abdominal strength and stability, says Jeremy Scott, trainer at Jeremy Scott Fitness in Scottsdale, AZ. That means better posture, strength that will carry over to other exercises, and a midsection that will be the envy of most washboards.

The bear crawl variations in this routine won't just hit your six-pack muscles, you'll also involve your lower back, shoulders, glutes, and even quads.

The feet-elevated cross-body mountain climber works all your ab muscles, especially the obliques. Your hip abductors and adductors will also be put to work as you stabilize while raising and lowering your feet from the bench.

The plyo bench plank hold is not only challenging to your entire core -- front and back -- but the explosive movement will ramp up your heart rate and add some fat burning into the mix.

At just over 5 and a half minutes, this routine means there is always time to fit in some serious ab work. (Get dozens of free workouts on your phone with the FREE Men’s Health App. Download it here.)

Perform the exercises below in the order listed for 20 seconds each:

1. Bear crawl reach.
2. Feet-elevated cross-body mountain climber
3. Plyo bench plank hold
4. Bear crawl step down

That's 1 round. Do 4 round with no rest.

More Men's Health:
-- Watch This Female Powerlifter Squash A Watermelon With Her Thighs
-- Build A Butt Women Will Want To Grab With This One Simple Exercise
-- The Rock's Secret Weapon For Building Muscle
-- This 5-Minute Core Workout Will Make Your Abs Beg For Mercy

Story continues below