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Have you studied your abs lately? We don’t mean how they look, but have you taken a moment to understand their make-up and appreciate all they do for you?
“The core’s primary function is providing the body with a pillar of strength and stability that is vital for performing everyday tasks and staying healthy,” says Lalaina “Lala” Duncan, a strength coach at New York City’s training gym Dogpound, where she has trained Olympic and professional athletes.
The 4 Layers of the Abdominal Wall
Your core is divided up into four areas of musculature, and Duncan says these four layers of the abdominal wall have distinct anatomical differences and functions that need to be programmed in certain movements to achieve the aesthetic and functional results desired. She describes each:
- Rectus Abdominis. The rectus abdominis runs the length of the abdomen from the xiphoid process to the pubis bone. It is split into right and left halves, not upper and lower halves. These right and left halves are separated by the linea alba, a thick band of connective tissue, and also crossed by three fibrous bands that give the appearance of a six-pack. Then there are those rare cases where some individuals have a fourth fibrous band, resulting in what looks like an eight-pack.
- External Oblique. The external oblique is the superficial of the two oblique muscles. It originates at the 5th and 12th rib, and inserts at the iliac crest, pubic tubercle, and linea alba. This muscle increases intra-abdominal pressure, flexes the torso, side bends the torso to the same side, and rotates the torso to the opposite side.
- Internal Oblique. The internal oblique muscle is located beneath the external oblique. It originates at the inguinal ligament, anterior iliac crest, and lumbodorsal fascia, and inserts at the linea alba, pecten pubis via the conjoint tendon, and the 10th and 12th ribs. This muscle provides support to the abdominal wall, is an opposing muscle to the diaphragm and assists in forced expiration, increases abdominal pressure, and flexes and rotates the torso to the same side.
- Transverse Abdominis. Often referred to as the “deep” abdominal muscles, this looks much like a muscular corset. The transverse abdominis originates at the iliac crest, inguinal ligament, thoracolumbar fascia and costal cartilages 7-12, and inserts at the diploid process, linea alba, pubic crest, and the pecten pubis via the conjoint tendon. This muscle’s primary function is to protect the internal organs and increase abdominal pressure so that you’re able to lift more weight.
“So, contrary to popular belief, there is no such thing as upper or lower abs,” says Duncan. “They are just plain old abs, or more accurately the rectus abdominis muscle. However, certain abs exercises do emphasize different portions of your core. To home in on your lower rectus abdominis (your six-pack muscle), add these ab exercises into your program.
3 Exercises to Sculpt Your Lower Abs
1. Reverse Crunch
How to: Lie on your back and extend your arms at your sides. Bend your knees to 90 degrees (calves parallel to the floor) and curl your hips off the mat to draw your knees towards your chest. Slowly lower. Repeat for two to three sets of 15 reps.
Expert tip: Try to focus on using your core and not your arms to lift your hips. “Once you’ve mastered good movement, try adding ankle weights or a medicine ball for added load,” says Duncan.
2. Seated Knee-In
How to: Sit upright on a mat, with your hands on the floor beside your glutes. (If you are more advanced, cross your arms in front of your chest.) Bend your legs to bring your calves parallel to the ground. Extend your legs and lean rearward, then return to the start. Do two to three sets of 15 to 20 reps.
Expert tip: The closer you lower your legs to the ground, the harder the exercise. Want to kick it up a notch? “Can you go no-hands on this,” asks Duncan. “Give it a try, slow and steady wins the ab race.”
3. Leg Scissors
How to: Lie faceup on a mat with your hands under your butt. Raise your legs about a foot off the ground, then lift your shoulders to come into a crunch. Keep your shoulders up as you alternate “scissoring” one leg over the other. Continue for 30 seconds, rest, then repeat twice more.
Expert tip: Beginners can keep their head on the mat to make this exercise easier. To make this more challenging, Duncan says you can add ankle weights, hold your hands by the side in a hollow body position, or increase the time under tension.