Pretty much everyone could use stronger abdominal muscles. Here's how to get them.
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Abs: many of us want them. But despite popular opinion, having a strong core means more than just looking good in a swimsuit. Each muscle that makes up the abdominal wall has its own purpose, but as a group they basically protect the spine and give us that perfect posture we're all striving for.

Pretty much everyone walking around on two feet could use a stronger set of abdominal muscles. So, how do we get them? Learning each muscle’s function and how it develops can give you a more intelligent approach to the way you train your abs. Of course, a healthy diet and a moderate amount of cardio are also a factor—abs are, first and foremost, made in the kitchen.

Here are the 4 key abdominal muscles and an exercise to target each one. We’re using a Swiss ball (and a BOSU trainer) for added resistance, because when you train your body in an unstable environment you recruit even more muscle tissue.

Note: Los Angeles-based personal trainer Kourtney McCullough demonstrated the exercises.

Rectus Abdominus

The rectus abdominus is the most superficial of all the ab muscles, meaning it's on top of everything else. It runs vertically down the front of your body and has the main role of flexing the body forward. When these muscles are developed, they grow outward. If your body fat percentage is low, this can create the "six-pack" look; but if you have a layer of fat sitting on top of these muscles it may cause you to look thicker, even though the muscles themselves might be strong underneath.

Go-to move: Pike to Plank on Swiss Ball
Exercises that contract or flex the spine forward will work the rectus abdominus. Place your shins on top of the Swiss Ball and walk your hands out to a plank position. Using your core, pike your hips up to an inverted V-shape (pictured), hold for 1 count, and then articulate your spine rolling back down to a plank. Be sure to continue pulling your navel in and keep your head in line with your spine as your move in and out of the movement. Do 15 reps.


Transverse Abdominus

Whereas the rectus abdominus is about flexing or bending the spine, the transverse abdominus is all about stabilizing the spine. The transverse abdominus wraps around the belly and is the most internal of all the core muscles. Its main function is to stabilize the pelvis and lower back prior to moving the body. Because it works to wrap around the spine, it becomes your body’s own personal corset, cinching in your waist. Regardless of your body fat percentage, developing the transverse abdominus muscle will help flatten your stomach so you'll look and feel better in your clothes without adding bulk.

Go-to move: Forward Swiss Ball Roll
The key to working the transverse abdominus is keeping the core stable, so planks are a great exercise. Kneel in front of a Swiss Ball with your forearms resting on the ball and your legs extended out behind you in a straight line (pictured). Slowly roll the ball forward with your arms on the inhale and then exhale drawing the ball back toward your center. Your arms are moving but the core is not. Be sure to keep pulling the navel in toward the spine and don’t roll the ball too far forward that you start to feel pressure in your lower back. Complete 15 reps.


Internal Obliques

The internal obliques lie beneath the external obliques and over the transverse abdominus muscles. They allow you to bend from side to side as well as twist your torso. Keeping your internal obliques strong can help you maintain a narrow waist, improve your posture, and also help keep your back healthy.

Go-to move: Swiss Ball Crunches with Leg Raises
Place your upper back on a BOSU balance trainer (a ball that's flat on one side) with both feet on the ground and arms stretched overhead. Exhale as you crunch, bringing your left leg and right arm up to meet each other (pictured) and then lower to the starting position. Do 15 reps and then switch sides.


External Obliques

The external obliques are a pair of broad, thin, superficial muscles that lie on the sides of your torso. No surprise: they're located on top of the internal obliques. They are best known for their lateral flexion and rotation of the trunk and get their name from the direction of their fibers, which run obliquely (diagonally) across the sides of the abdomen.

Go-to move: Torso Twist on Swiss Ball
The torso twist heavily recruits your external obliques thanks to the rotational movement. Lie on your back on the Swiss Ball holding one 10- to 15-pound dumbbell with both hands (pictured). Start to twist the torso, moving the weight toward the right side and then back to center. Be sure to engage your core and move slowly to get the benefit of the exercise. Do 20 reps on the right side and then repeat on your left side.


To work your booty in addition to the abs, check out 5 Moves to Perk Up A Flat Butt.

Jennifer Cohen is a leading fitness authority, TV personality, entrepreneur and best-selling author of the new book, Strong is the New Skinny. With her signature, straight-talking approach to wellness, Jennifer was the featured trainer on The CW’s Shedding for the Wedding, mentoring the contestants’ to lose hundreds of pounds before their big day, and she appears regularly on NBC’s Today Show, Extra, The Doctors and Good Morning America. Connect with Jennifer on Facebook, Twitter, G+ and on Pinterest.