The Only Do-Anywhere, 3-Move Abs Workout You'll Ever Need

The plank may be the perfect exercise because of the sheer number of muscles that it engages all at once. That's why you'll see them happening almost every time you walk into your gym. You'll get much more out of a plank than just an abs workout, but since we are discussing abs, the plank primarily works your rectus abdominis (your superficial abs — those that you show off) and your transverse abdominis (deep internal abs — or the "internal girdle," as Chadwell likes to call it).

When you work the rectus abdominis, you are developing the coveted six-pack. When you work the transverse abdominis, you are strengthening your abs at the deepest level. This is important for keeping your midsection muscles sucked in tight toward your spine. If you've had children, the plank should be in your ab arsenal for this very reason.

How to Do Plank:

• Get into push-up position.
• Bend your elbows to a 90-degree angle and hold your weight on your forearms. Your elbows will be directly underneath your shoulders. Your body will form a straight line from your head to your feet.
• Look down at a spot on the floor to ensure a neutral spine. Make sure your stomach is not sagging toward the floor.
• Squeeze your glutes.
• Hold the position for one minute.

A two-pack or four-pack is great, but why not go for the gusto and work for the entire six-pack? Chadwell said, "Your lower abs are going to put up a fight! They are the most stubborn, so you have to include a core exercise that targets your lower abdominals. That's where the double crunch comes in."

The double crunch, as the name suggests, does two jobs simultaneously. It strengthens your upper and lower rectus abdominis.

How to Do the Double Crunch:

• Lie on the floor on your back.
• Place your hands on the back of your head so that you are cradling it.
• Lift your legs so that your knees are bent at a 90-degree angle and your lower legs are parallel to the floor.
• Contract your abs to lift your hips off the floor while simultaneously raising your upper body off the floor. You are doing both a crunch and a reverse crunch at the same time. Don't lift your head with your hands. Use your upper abs.
• Hold for a one count, and slowly return to the starting position.
• Repeat for 25 reps.

Here's an exercise that you can literally do anywhere, even in your office chair, and the person sitting closest to you in the office will not know you are doing it. It's the vacuum. You are literally tensing your deep abdominal muscles in toward your spine and holding them under tension in order to increase their strength.

"I used these during contest prep for bodybuilding. Both of my trainers were adamant that I use these in the car on my way to work, sitting at my desk, and during ab training at the gym. They seem easy, but if you are drawing in hard enough, you almost feel a bit breathless," Chadwell said.

How to Do the Vacuum From Standing Position:

• Stand up straight.
• Place your hands on your hips.
• Exhale all the air out of your lungs and diaphragm.
• Expand your chest, and pull your stomach in as much as possible. Hold. Envision trying to pull your belly button to your backbone.
• After holding for 20-50 seconds, or as long as you can tolerate, release and repeat.

How to Do the Vacuum Lying Down:

• Lie on your back with your legs straight and arms out flat by your sides.
• Exhale all the air out of your lungs and diaphragm.
• Squeeze your abs, and pull your stomach in as much as possible. Hold. Envision trying to pull your belly button to your backbone.
• After holding for 20-50 seconds, or as long as you can tolerate, release and repeat.

A stomach vacuum can be performed many ways: standing, on all fours, kneeling, seated, and lying down. Experiment with each position to see which way works best for you.