This is partly an ab
exercise, partly a leg exercise, partly a shoulder
exercise, partly a back exercise and very a much a
total-body exercise.
The concept is simple...pick
up a single dumbell then swing it up as high as you
can in front of you!
There are some tricks
to it, though.
First, you'll need a
moderately heavy dumbell. Start moderate the first
time you do it so you can get an idea of how much
you can handle. I'm using a 115 lb dumbell here.

Squat down and pick
it up, gripping on the handle with both hands (one
hand will lock over the other).

Come up a bit then swing
the dumbell forward a bit to get some momentum.

Now swing the dumbell
back between your legs.

NOW power it up as high
as you can using leg power, ab power, shoulder power
and back power!

You're not trying to
do a front raise with this...you're trying to swing
that dumbell high and powerfully!

Let the dumbell swing
back down again to the position behind your legs.

For me, because of how
heavy the dumbell is, I don't want to immediately
try and swing it back up - that'll put a lot of torque
on the lower back. So I set the dumbell down on the
floor here.

Then I begin the rep
again just as I described. You'll see exactly what
I mean in the video.
Basically, lift it up,
swing it forward a bit, then take a backswing then
heave it up!
This is an excellent
exercise for building total-body power and, believe
me, you'll get a cardio workout out of it, too.