The stomach vacuum involves pulling your belly button to your spine. Image Credit: fizkes/iStock/GettyImages

Sucking your belly in to get a slim stomach seems too good to be true, but it's a real technique. Embraced by gym rats, yogis and weight lifters, the stomach vacuum, as it's called, is a powerful way to train your transverse abdominis.

Your transverse abdominis is the deep internal ab muscle responsible for good posture, organ support and impressive feats of core strength.

The stomach vacuum works because you're tensing the internal ab muscle for an extended period of time. It's not the only exercise you should do for your abs and core, but it is a valuable, do-anywhere move that can be part of your repertoire.

The stomach vacuum is super convenient because you can really do it anywhere — in the gym, of course, but also sitting at your desk at work or when stuck in traffic. The move does take practice, so use any opportunity you think of it to do it.

Purpose of the Vacuum

While you may perform the vacuum to develop defined abs or to add power to lifts, it has other functional purposes. Bodybuilders use the vacuum to "pose" on stage and show their muscles off to judges.

In yoga, a variation of the stomach vacuum called uddiyana bandha — or upward abdominal lock — is performed to increase bodily control, breath focus and balance. In belly dancing, the vacuum trains your abs to perform flutters and rolls.

Stomach Vacuum Exercise

The stomach vacuum — also called abdominal draw in — is a powerful isometric exercise and, although it sounds easy, it requires intense control.

Lie on your back, legs straight and arms by your sides. Exhale all the air out of your lungs and diaphragm. Tighten your abs and squeeze, like you're trying to pull them under your rib cage. Hold for 20 to 60 seconds, depending on your tolerance.

Tip The stomach vacuum can also be performed from a forward-lying position, all fours, standing or seated. Try all the positions and settle on the one that allows you to execute it the best.

How to Get Results

While the stomach vacuum is a powerful transverse abdominis strengthener, it isn't automatically going to give you a six-pack. You still need to do exercises that train the rectus abdominis — the front sheath of your abs that appear as the defined six-pack — and the side obliques responsible for rotation.

If you have a layer of fat covering your abs, you'll also have trouble seeing aesthetic results from the stomach vacuum. Most women need a body fat percentage of between 14 percent and 20 percent for women and men, 6 percent to 13 percent, to see a six-pack. This is quite lean and only attainable with a diligent diet and exercise ethic.

You may feel stronger and be better able to execute intense lifts during strength training because the vacuum's effects on the deep ab muscles makes you better at powerfully exhaling during contractions. It'll also give you better awareness of the control you have over your abs, which gives you more power when you do big strength moves, such as a barbell snatch.

Warning The stomach vacuum can raise your blood pressure as you isometrically contract the muscle. If you have high blood pressure or are pregnant, skip the move entirely.