Your Ab Muscles Explained
The two figures standing in front of me one recent winter morning could not look more different. On the right is Carrie McCulloch, MD, a musculoskeletal anatomy expert and the medical director for Kinected Pilates studio in New York City, who is sizing up the shape of my waistline. Dr. McCulloch’s own midsection happens to be perfectly rounded because she is only weeks away from giving birth to her first child. On the left is her assistant, Mr. Bones, one of those hanging skeletons that teach medical students how the thigh bone’s connected to the hip bone. Mr. Bones doesn’t actually have a waist, just a hollow space between his ribs and pelvis.
Dr. McCulloch is demonstrating how this inner bony foundation can set the stage for your torso’s outer appearance, tapping the stacked bones that make up her assistant’s spine.
I ask Dr. McCulloch how I ended up with a relatively slim 26-1/2-inch waist that has forced me to belt every pair of pants I’ve ever bought in order to cinch the gap created by wearing sizes big enough to fit my more ample bottom. The answer includes factors like body type, fat composition, and possibly even the shape of the pelvic bone, where your ab muscles attach, she says. Theoretically, a wider pelvis can translate into a broad lower abdomen and hips, compared with what’s north of the belly button. “These are all variations on normal, and genetics can play a big role,” she assures me.
But even though I weigh less now than I did in my twenties — thanks to a mostly vegetarian diet and a love of Zumba Fitness classes — I notice something new: a muffin top, a spare tire, love handles. Whatever you call it, I’ve got it. And I’m about to loan my body to science to get rid of it.
When it comes to ab flab, there are two ways to tackle the problem: Either burn blubber or suck it in with stronger muscles. “Even if you don’t lose fat, you can improve your waistline by toning your muscles,” says Michele Olson, PhD, a FITNESS advisory board member and professor of physical education and exercise science at Auburn University at Montgomery in Alabama.
The skinny on abs is that they’re actually hard to fatigue because they work all day long to keep you upright. But you don’t come home after a long day at the office with a tummy ache from all that typing, so how busy could they really be?
“When we’re seated, our back muscles and spine help keep us upright and the abs are in a slack position, especially if you slouch,” explains Joseph Herrera, a doctor of osteopathic medicine and the director of sports medicine at Mount Sinai School of Medicine Department of Rehabilitation Medicine in New York City. “Although we would end up reclining without the opposing muscle forces they provide, intentionally contracting your abs is the only way to activate them as you sit.” As I stand in his office, Dr. Herrera tapes electrodes beneath my rib cage and just above my belly button. Cables connect those electrodes to an electromyography (EMG) machine, which makes a whooshing sound every time the underlying
muscles — my external obliques and rectus abdominis — are activated.
The external obliques are the V-shaped muscles running diagonally down your sides that, along with the internal obliques underneath them, help you rotate your spine when a Ryan Gosling look-alike walks by. The rectus abdominis, meanwhile, is the straight-down-the-center muscle which, yes, can make you appear to have a six-pack if you have a seemingly single-digit body-fat percentage like Ryan Gosling’s. The one remaining ab muscle, which Dr. Herrera’s surface EMG won’t be picking up, is the transversus abdominis. The deepest-down of all, it does a complete wraparound of your midsection and pulls it in like a corset.
When I sit in my chair with the electrodes in place, nothing happens. So I switch over to sit on a pumped-up stability ball, like the kind every office health nut uses. No whoosh. But then I lean slightly backward and all of sudden — whoosh — my rectus abdominis activates to support my spine because there is no backrest to do the job. “The stability ball requires your torso to balance on an unsteady surface. It forces your abs to fire,” Dr. Herrera says. I find I can also activate the rectus abdominis, not to mention my heretofore-napping obliques, by pulling in my belly button. I feel like a living Wii game avatar as I subsequently walk around Dr. Herrera’s office trying to get a reaction from the EMG. Walking itself produces only a weak whoosh, but by carrying a bag of groceries in front of me, slinging my purse over one shoulder, or climbing stairs, I get the electrical activity on the EMG monitor to increase.
Of course none of this multitasking is making my abs burn or getting them closer to bounce-a-quarter-off-’em shape. For that, you have to do the type of middle-cinching muscle toning that Olson was referring to.
Olson has in fact used this same sort of EMG machine to test just about any ab exercise you can name. Thanks to her, for the next four weeks I’ll be doing the mother of all ab workouts: a routine that contains her and her fellow scientists’ greatest hits. (Spoiler alert: You get to do it, too, with the Flat Abs Fast workout below.)
Get the 9 Exercises for Flat Abs
How to Get Rid of Belly Fat
Your Ab Muscles
Along with muscles in the lower back, these key abdominals make up your core.
The outer layer of the abs on your sides; these run diagonally downward.
Just underneath the external obliques, these run diagonally up your sides.
Two paired sheets of muscle from the ribs to the pelvis that flex you forward.
The deepest ab muscle, which wraps around the waist to support the spine.
Think of your ab muscles as the meat in the middle of a fat sandwich. On top of them is subcutaneous fat, the stuff you pinch as you look in the mirror. Below them is visceral fat, which is the type that takes up residence next to your internal organs — in excessive amounts if you continually overdo it on calories and experience too much pent-up stress. “When you fill up those subcutaneous areas, fat winds up getting stored where it shouldn’t, in your deep abdomen or your liver,” explains Arthur Weltman, PhD, exercise physiology professor at the University of Virginia in Charlottesville. Visceral fat has been linked to heart disease, type 2 diabetes, and metabolic syndrome, he notes.
But because you don’t have X-ray vision to see whether too much of the potentially dangerous visceral fat is parking itself in your own belly, scientists have figured out a couple of DIY guidelines. To avoid increased risk of obesity-related diseases, women should have a waist measurement no bigger than 35 inches (measure it at the smallest point of your midsection), and some experts recommend a waist-to-hip ratio of around 0.8, meaning that your waistline should be no greater than 80 percent of your hip circumference. According to a Mayo Clinic study released last May, the ratio of waist to hip is believed to be a measurement of visceral fat. Other fascinating research, published in the
American Journal of Human Biology
, found that women who give birth before age 40 have an average of two centimeters more fat around their bellies than women of the same ages who haven’t given birth. (I’ll have to thank my two daughters for those extra centimeters.)
Just don’t wait until you blow the tape-measure test to start defending your belly from this flab. Step one is to toss the trans fats, which are found in prepackaged treats under the alias partially hydrogenated oils and have been shown to pack on body fat, particularly in the abdomen. Replace them with monounsaturated fats — for example, olive oil and those in walnuts and avocados — which help your body metabolize belly fat. And swig some reduced-fat milk, like 1 percent or skim, while you’re at it: Calcium increases the activity of enzymes that break down fat cells and reduces the stress hormone cortisol, which triggers your body to hoard belly fat.
Step two is to get some calorie-burning cardio exercise. Of course you’ve already heard that pointer often, but Weltman takes this idea one step further, noting that high-intensity aerobic exercise is even more effective at burning off visceral fat than the same amount of low-intensity exercise. In one study, he had overweight women walk or jog five times a week; one group worked out for a longer amount of time at a low intensity, while the other did shorter stints of high-intensity work. Even though each group burned the exact same number of calories in each workout, the high-intensity group melted off more visceral fat. “We speculate that there’s a relation between the intensity of the workout and the amount of growth hormone released, which is a powerful mobilizer of visceral fat,” Weltman says.
The good news, according to Weltman, is that high intensity — the level at which you feel the effort and can no longer hold a conversation — is different for each person. “You may have to run to get to that level, while someone else may just have to jog or walk,” he explains. “It all depends on your level of fitness, but the great thing is, you can do it whether you’re a competitive athlete or just starting out.”
I make a mental note to bust the moves in Zumba class like never before.
The Flat Abs Workout Plan
The perfect six-packed specimen illustrating this story is my abs exercise instructor, Chelsey Korus.
At my first workout with her, I watched Korus demonstrate the tolasana pose. Sitting cross-legged with her palms resting on yoga blocks next to her hips, she straightened her arms and, using only her ab muscles, raised her body off the floor. When I attempted it, I couldn’t even lift one butt cheek off my mat. Never mind my muffin top; I wondered how my abs had gotten so wimpy. After all, it had been eight years since I’d had my second daughter, so those muscles should have bounced back long ago.
Moves like the tolasana and the eight subsequent ones we did that day are representative of a shift that ab exercises have taken in the past decade or so. Previously there was a tendency to isolate the abdominal muscles to give each one an individual workout — crunches for your rectus abdominis, bicycles for the obliques — but as Olson points out, that’s not the way it works in real life. “When you’re reaching up to get something, picking up a baby or bending down, you need all the muscles to work together,” she says. “Instead of targeting each one, you should aim for functional fitness, where the muscles work as a unit.”
By week two of my abs regimen, I could actually lift my butt off the floor for a few seconds of tolasana, and in week three I kept asking my husband to feel how tight my obliques were getting. At the end of the month I could hold the pose for at least 15 seconds and not make what Korus called my “stress face.”
I lost a half-inch from my waist in four weeks without dieting. Now every time my daughters cheer me on as I achieve liftoff during tolasana, I feel as if I can kick some major butt. Supported by my awesome abs, of course.
Get the 9 Exercises for Flat Abs
Meet other women who managed their waistlines
To Crunch or Not to Crunch?
Lately the common sit-up has stirred controversy, coming under fire from certain experts for putting excessive wear and tear on the spine. While evidence is mounting but the jury is still out, try this simple back-friendly modification from Stuart McGill, PhD, professor of spine biomechanics at the University of Waterloo in Canada and author of
The Ultimate Back Fitness and Performance
: Lying faceup on the floor, slip your hands underneath the natural curve of your spine. “You can activate the rectus abdominis with tiny upward movements, as if you’re lifting your head and shoulders off a bathroom scale so it registers zero,” he explains.