How To Do It

For this exercise, you will need two dumbells and a Swiss Ball (I will also tell you how to do the exercise on a regular flat bench in the Tricks section below). A smaller-size ball is better for this exercise though any ball will work.

Lay on your back on the ball with your knees bent and your feet fairly wide apart - you'll need a good base of support for this exercise so that you don't roll off to the side of the ball. Hold two equal-weight dumbells at arms-length directly above you. Press them together while doing this exercise (if they're separated, they'll move around more, making the exercise less efficient). Start with fairly light dumbells the first time you try this movement.

Now, keeping your head facing directly up/forwards and your hips horizontal, lower both of the dumbells slowly and under complete control down to the left. Hold your breath and tighten up your midsection as you come down to the fully-twisted position. Prepare to push hard against the ground with your left foot to maintain your balance.

Your left arm is going to bend to about 90 degrees at the elbow as you lower the dumbells to the side while your right arm should stay perfectly straight. Your upper body should stay in the same position on the ball - no rolling to the opposite side to compensate for the weight to the side. This torque is what makes the exercise so valuable. Bending your lower arm is critical to keeping your torso in the same position on the ball.

Since you're using two separate dumbells, it's going to be a very different stress on the entire abdominal area than anything you've experienced before.

When you're at the bottom, your upper left arm will be contacting the surface of the ball (don't let it rest or lose tension at this point!). Reverse the direction by simultaneous pulling with your right side abs and pushing with your left side abs. The right arm movement is similar to a rear delt lateral while the left arm movement is similar to a dumbell press.

Remember to keep the dumbells pressed together tightly! The opposing tension in the abs really puts a lot of torque across the whole area. Be very sure you're not just pushing with the bottom arm but also pulling with the top arm.

Be sure not to bounce out of the bottom and try to feel a stretch in the right side as you start the change of direction.

COMMON ERRORS:

1. Separating the dumbells

Keep them pressed together throughout the movement. If they separate, they're harder to control and it disperses the tension on the abs.

2. Rolling around on the ball

For best results, be sure to keep yourself as stationary as possible on the ball. If you roll to the side, it takes some of the torque off the abs and it won't hit the abs as strongly.

3. Moving too quickly

This is NOT a ballistic exercise - there should be no bouncing or fast movements involved. Lower the dumbells slowly to the sides and change direction very deliberately using muscle power, not bouncing.

TRICKS:

1. Changing the arc

You can bring the dumbells down at various angles to the torso to change where the exercise hits your abs. By bringing it down higher up beside your head, you'll hit the upper areas of your obliques. By bringing it down towards your hip, you'll hit the lower areas of your obliques. Just remember to always keep your head looking straight up and set your feet wide apart for the best base of support.

2. How to use a flat bench instead

You can also do this exercise on a flat bench instead of a ball, if you don't have access to a ball or prefer a more solid surface to work on. Instead of lying flat on the bench as you normally would for a bench press, you'll be resting only your upper back on the end of the bench.

To get into this position, sit on the very end of the bench. Now move your butt off the bench and squat down in front of it. Lean back and place your upper back on the bench end. Keep your hips down and set your feet fairly wide apart.

This is the position you should maintain while doing the exercise. The bench is a more solid surface but it just as effective for the exercise. One major difference is that there won't be any surface to contact the upper arm of the bottom arm as you lower the weight down. Keep an eye on how far down you go to the side. All the other techniques still apply.

3. When using heavier weight...

You can shift your upper body somewhat to the other side of the ball. If you're using a heavy weight, you'll need to do that in order to stay on the ball. The increased resistance will make up for it. Be extra careful the dumbells don't separate. It'll be much harder to control heavier dumbells if they do. As you rotate back up, exhale through pursed lips to keep stability in your abs yet let air out so you don't pass out. Push VERY hard with the same side leg as the weight is on. You'll need all the help you can get.

This exercise will really hit the sides and stabilizing core muscles strongly. Your entire midsection will feel much tighter after a few sets of this exercise.

-Nick Nilsson