This one isn't going to look like any ab exercises you've ever seen...unless you've seen my Dumbell Crawling exercise...then you might be familiar with the concept.

Basically, you're going to grab 2 heavy dumbells (I'm using 125 lb dumbells in the demo) and you're going to slide them forward then backward across the floor.

Nothing complex about this one...basically, we're mimicking manual labor here :)

So set the dumbells together on the floor and stand with your feet on either side. Reach down and grab them.

Now use your whole body (your core will be where the focus becomes - it's just how that works) to slide the left dumbell forward as far as you can.

Now slide the right dumbell as far forward as you can.

Step your feet up then slide the left dumbell forward again as far as you can.

Same again for the right dumbell...get the drift here?

Once you've gone as far forward as you can (or just pick a distance - in my gym, this was as far as I could go).

Now you're going to go backwards...I'm going to pull BOTH dumbells backwards the first time through. Notice how I'm sitting back and using bodyweight in addition to muscle power to slide the dumbells.

Pull them back then step backwards.

Repeat - do the same thing, putting your bodyweight into it.

Now I'm all the way back and ready to go forward again. This time, it's going to be moving forward with both dumbells at once. Stand so your feet are a bit FORWARD of the dumbells. You'll need to place them there to get traction on the dumbells.

Heave them forward then step forward.

Go all the way forward again. Now on the way back, I'm moving one dumbell back at a time. Same deal about using bodyweight to help with the movement.

Keep going until you're all the way back.

I just did two rounds, forward and back, and that was plenty.

This is an excellent functional exercise, not only for the core but for the entire body. It's not pretty but it's great training!