Complete Guide to Abs Anatomy and Exercises That Work Your Abs and Core (2024)

The ab muscles are part of the core, and strong core muscles are essential for all of us. Building strong abs can help you with daily activities like standing, sitting, reaching, and bending. Core strength can also lead to better posture and help prevent injuries and back pain.

If you're getting tired of doing endless crunches and seeing no results, then it might help to learn the ins and outs of your core anatomy and the science behind building muscle. For one thing, your abs aren't just one muscle — and you'll need to diversify your exercise routine to work every type of abs muscle and really see results.

Here, get to know each type of abs muscle, plus how to work them in the most effective ways.

Meet Your Abs Muscles

First, a little anatomy lesson. Along with muscles in the lower back, these key abdominals make up your core:

• External Obliques: The external obliques are one of the outermost abdominal muscles. They run diagonally downward from the lower portion of the ribs down to the pelvis. These muscles allow you to stabilize your core, rotate your trunk, and bend your body from side to side.
• Internal Obliques: Just underneath the external obliques, the internal obliques run diagonally up your sides from the pelvis to the lower ribs. Like the external obliques, the internal obliques also allow you to rotate your trunk and bend your body from side to side.
• Rectus Abdominis: The rectus abdominis is composed of paired sheets of long, straight muscles that are located in the middle of the abdomen, from the ribs to the pelvis. These are the muscles that you use to flex yourself forward. (They are also the ″six-pack" muscles most people visualize when thinking about the abs.)
• Transversus Abdominis: The deepest muscle of the abs, the transverse abdominis muscle wraps around the waist to support the spine. This muscle is at work when you compress your stomach toward your spine. In addition, this important core muscle helps prevent instability and supports the lower back.

Yes, there are separate muscles, but they all work together. 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. The rectus abdominis, meanwhile, is the straight-down-the-center muscle which, yes, can make you appear to have a six-pack. The one remaining type of abs muscle is the transversus abdominis: The deepest-down of all, it does a complete wraparound of your midsection and pulls it in like a corset.

What Determines the Visibility of Your Abs Muscles?

Think of your abs muscles as the meat in the middle of a fat sandwich: On top of them is subcutaneous fat, the stuff you can potentially see from the outside, depending on your body composition. Below them is visceral fat, which is the type that takes up residence next to your internal organs, which is protective in small amounts, but can lead to health consequences when too much builds up.

"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, Ph.D., an 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. It's impossible to know how much visceral fat you have just by looking in the mirror, so seeing a doctor is the only surefire way to find out if you have too much. However, factors such as your Body Mass Index (BMI) and your waist circumference can help you determine if you may be at a health risk.

You can also implement these strategies to help reduce visceral fat:

Limit Trans Fats

Step one to combat visceral fat is to toss the trans fats, which used to be found in prepackaged treats under the alias "partially hydrogenated oils." These are being phased out and are mostly absent from supermarket shelves since scientists discovered how unhealthy they are for your organs and beyond. (The World Health Organization set a target to eliminate artificial trans fats worldwide by 2023.)

Instead of trans fat, seek out more monounsaturated fats, found in foods such as olive oil and avocado, and polyunsaturated fats, found in foods such as walnuts and salmon. These fats can help reduce your risk of cardiovascular disease, according to the Food and Drug Administration.

Get More Exercise

High-intensity aerobic exercise like HIIT (High-Intensity Interval Training) is more effective at burning off visceral fat than the same amount of low-intensity exercise, notes Weltman. In one of his own studies, 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 lost 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," explains Weltman.

The good news is that high intensity — the level at which you feel the effort and can no longer hold a conversation — is different for each person, according to Weltman. "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," adds Weltman.

Does the thought of strapping on your running shoes fill you with dread? Well, lifting weights has also been shown to reduce visceral fat (as well as these other health and fitness benefits). A study in the journal Obesity from the University of Alabama at Birmingham found that subjects who strength trained lost more visceral fat than participants who just did cardio. Plus, they kept that visceral fat off after a year if they kept up the weight training, even if they gained weight overall.

The most important factor to consider? When choosing which type of exercise to do, prioritize what you like to do and feel motivated to keep up.

How to Build Stronger Abs Muscles

If you want visible, defined abs, losing weight is not a prerequisite — just work on toning the muscles, says Michele Olson, Ph.D., senior clinical professor of exercise physiology at Huntingdon College in Montgomery, Alabama. To build up your core strength, it's important to work every type of abs muscle in your body (instead of, say, just focusing on the rectus abdominis). And, turns out, the abs are pretty 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 sore core from sitting at your desk, so how busy could they really be? "When you're seated, your back muscles and spine help keep you upright and the abs are in a slack position, especially if you slouch," explains Joseph Herrera, D.O., a doctor of osteopathic medicine and the director of sports medicine at Mount Sinai School of Medicine's Department of Rehabilitation Medicine in New York City. "Although you 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," he notes.

So how do you wake up those deep abs muscles if you're working at a desk all day? In a standard chair, your core muscles need not pull their own weight. But sit on a pumped-up stability ball (with no backrest) and the rectus abdominis activates to support your spine. "The stability ball requires your torso to balance on an unsteady surface. It forces your abs to fire," says Dr. Herrera. (You can also do these advanced core exercises with the help of a stability ball.)

In addition, you can activate the rectus abdominis and obliques by simply pulling in your belly button. To get functional benefits from your core workouts, you'll want to prioritize movements that activate more than one type of abs muscle. Previously, there was a tendency to isolate the abs muscles to give each one an individual workout (crunches for your rectus abdominis, bicycles for the obliques, and so on), but that's not the way it works in real life, notes Olson.

"When you're reaching up to get something, picking up a baby, or bending down, you need all the muscles to work together," explains Olson. "Instead of targeting each one, you should aim for functional fitness, where the muscles work as a unit," she recommends.

Abdominal Muscle Exercises

Looking for ab exercises that target different abdominal muscles? Here are a number of abdominal exercises with modifications and variations for different fitness levels.

Planks

• Abdominal muscles targeted: Rectus abdominis, obliques, transverse abdominis
• Instructions:
• A. Start in a table-top position on the floor with hands stacked directly under shoulders, knees bent and stacked directly under hips, and feet hip-width apart.
• B. Lift both knees off the floor and straighten legs to come into a high plank position on palms, squeezing glutes together and engaging core. Actively push away from the floor and maintain a straight line from head to heels.
• C. Hold position for 30 seconds.
• Proper form:
• Tighten the core throughout the exercise.
• Make sure elbows are directly under the shoulders.
• Keep forearms parallel to one another.
• Keep your focus toward the ground slightly in front of you.
• Recommended sets and reps:Hold plank for 30 seconds. Do 3 sets.
• Modification:
• Forearm Plank
• This variation takes the pressure off the wrists and is ideal for anyone with wrist issues.
• A. Begin in regular plank position.
• B. Lower one forearm down to the floor at a time, elbows in line with shoulders. Plant palms firmly on the floor or create gentle fists.
• C. Lift both knees off the floor and straighten legs to come into a forearm plank position, squeezing glutes together and engaging core. Actively push away from the floor and maintain a straight line from head to heels.
• D. Hold position for 30 seconds.
• Progression:
• Side Plank
• Side planks target the internal and external obliques.
• A. Lie on left side with knees straight. Prop body up on left elbow and forearm, keep feet stacked.
• B. Raise hips until body forms a straight line from ankles to shoulders.
• C. Tighten core and breathe deeply for the duration of the plank exercise.
• D. Hold position for 30 seconds. Switch sides; repeat.
  

Jackknife

• Abdominal muscles targeted: Transversus abdominis
• Instructions:
• A. Lie face-up on a mat on the floor.
• B. Extend arms above head and both legs straight on the floor.
• C. Bend knees and bring them toward chest.
• D. Inhale, then exhale and lift torso from floor and bring knees toward chin and both arms to knees.
• E. Slowly lower arms and legs toward the floor at the same time.
• Proper form:
• Tighten the core throughout the exercise.
• Don’t allow shoulders to hunch.
• Keep arms straight.
• Recommended sets and reps: Do 10 reps.
• Modification:
• Start with a hollow hold
• A. Lie face-up on a mat on the floor.
• B. Stretch your arms straight out above your head.
• C. Keeping your arms and legs straight, raise both arms and both legs off the floor at the same time.
• D. Tighten abdominal muscles.
• E. Hold position for 10 seconds.
• F. Lower arms and legs to the ground and repeat.
• Progression:
• Straight-leg jackknife
• A. Lie face-up on a mat on the floor.
• B. Extend both legs forward, pressing them together, and keeping them straight. Extend both arms straight behind head.
• C. Inhale, then exhale and lift arms and legs up at the same time, squeeze the abs in to create a “V” body position.
• D. Slowly lower arms and legs toward the floor slowly and at the same time. Try not to allow the arms and legs to touch the ground.
  

Crunches

• Abdominal muscles targeted: Rectus abdominis
• Instructions:
• A. Lie face-up on the floor with knees bent and feet flat on the floor about hip-width apart.
• B. Pull lower back in and down toward the floor, tilt pelvis slightly.
• C. Tuck chin in toward chest and place hands at your sides.
• D. Engage abs, exhale, and slowly lift shoulder blades off the floor.
• E. Pause, then slowly lower back down to starting position.
• Proper form:
• Keep the movement small and compact.
• Don’t raise your upper body beyond shoulder blades.
• Recommended sets and reps: 1 to 3 sets, 10 to 12 reps.
• Modification:
• Reverse Crunch
• A. Lie face-up in a traditional crunch position, knees bent and feet flat on the floor.
• B. Place hands underneath head with elbows wide or at sides.
• C. Press lower back into the floor and pull in belly button to lift feet off the floor. Bend knees at a 90-degree angle, keeping them together.
• D. Using core, draw knees toward chest so that tailbone raises off the ground.
• E. Slowly lower feet back to floor, repeat.
• Progression:
• Exercise Ball Crunch
• A. Lie on the ball, positioning it under the lower back.
• B. Cross your arms over the chest or place them behind your head.
• C. Contract the abs to lift torso off the ball, pulling the bottom of your ribcage down toward your hips.
• D. Use core to lower torso back to exercise ball, repeat.

Standing Side Crunch

• Abdominal muscles targeted: Obliques
• Instructions:
• A. Stand with feet shoulder-width apart.
• B. Place hands behind head, lace fingers together, keep elbows out to the sides.
• C. Bend to the side, bringing your rib cage toward your hip bone, and squeeze.
• D. Stand up straight and repeat on the other side.
• Proper form:
• Avoid bending forward.
• Make sure hips are square and you’re bending to the side.
• Recommended sets and reps: 15 reps on each side.
• Modification:
• For beginners, bend body only slightly to the side, as much as is comfortable. Maintain proper form and work up to a full side bend.
• Progression:
• Side Crunch with Leg
• A. Stand with feet shoulder-width apart.
• B. Place hands behind head, lace fingers together, keep elbows out to the sides.
• C. Shift weight onto the left leg and raise right knee toward right elbow as you bend toward the right.
• D. Squeeze and engage core as you crunch.
• E. Stand up straight and repeat on left side.
  

Common Misconceptions About Abs Muscles

While everyone has the same abs muscles, their appearance differs from person to person. The shape of your midsection boils down to a formula that includes factors such as body type, fat composition, and possibly even the shape of the pelvic bone, where your abs muscles attach, says Carrie McCulloch, M.D., a musculoskeletal anatomy expert and the medical director for Kinected Pilates studio in New York City. Some people build muscle more easily than others, and everyone's waist shape is different. That means that, theoretically, a wider pelvis can translate into a broad lower abdomen and hips, compared to what's above the belly button. "These are all variations on normal, and genetics can play a big role," says McCulloch.

So, while there are things that you can control when it comes to strengthening and toning your abs muscles, there are some things are out of your control. You can make difference with diet, exercise, and rest (including sleep). In addition to regular training, make sure to consume a clean and healthy diet that includes fresh fruits and vegetables and avoid fast foods,