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Tone Your Abs: Understanding Abdominal Muscles and Crunches


Updated February 15, 2014

rectus abdominis

Working the rectus abdominis properly and consistently will help you flatten your abs.

Photo © A.D.A.M.

Abdominal muscles are one of the first areas many people are eager to work on as they begin to lose weight. Belly fat can be particularly difficult to get rid of; the only way to reduce it is with a healthy diet and cardiovascular exercise (spot reduction just doesn't work). The good news is that performing exercises to tone and strengthen the muscles in your abdominal area will help your stomach appear flatter once belly fat is reduced. But before we discuss toning your abs, we should take a closer look at your abdominal muscles:


Understanding Ab Muscles

The area of the body commonly referred to as "the abs" is a combination of four muscles:





In addition to reducing abdominal fat with diet and aerobic exercise, to effectively flatten your abdominal area, you will need to work all four muscles, on average, two to three times a week. This may sound daunting, but keep in mind strong abs don't just mean achieving a flatter belly for appearance's sake. They're also a part of good posture, help alleviate lower back pain and are an essential aspect of long-term health and well-being.

To learn more about abdominal muscles, see Abdominal Muscles: Where They Are and How They Work.


Why and How to do a Crunch

One of the best ab exercises for beginners to get started with is the "traditional" or "classic" crunch. Traditional crunches work the rectus abdominus, which is the most prominent of abdominal muscles. Working your upper and lower abs (rectus abdominus) also works the transverse abs (torso).

To do a classic crunch, lie on your back, put your feet flat on the floor, and bend your knees. Clasp your hands loosely behind your head. Tilt back, flattening your back against the floor. Slowly curl your shoulders up from the floor (about 30 degrees up), making sure you don’t pull up on your neck. Hold for about a second and then lower. Repeat for two sets (groups) of 8 to 12 reps (repetitions) and work up to three sets of 10 reps.


Why Doing it Right Matters

While crunches may be a good exercise for beginners, they still need to be done properly. According to About.com's Guide to Sports Medicine, most people don't do crunches correctly, but it's important that you do. "Using good form when doing a crunch makes this a much more effective abdominal exercise," says the Guide to Sports Medicine. Proper technique not only impacts how effective the exercise is; doing crunches incorrectly can actually lead to back problems.


Proper Technique Pointers

Remember these pointers when performing crunches:






  • Always exhale as you contract (bend) and inhale as you release (go back to starting position) during the crunch.
  • You should never pull on your neck when doing a crunch. If you can’t clasp your hands behind your head, you can cross them over your chest instead.
  • Always keep your chin a fist's distance from your chest when doing a crunch. You can actually rest your fist under your chin. Doing so keeps your head from moving (which can cause your neck to go out of alignment).
  • Move slowly and continuously as you do the crunch (don’t jerk your body upwards).
  • You should keep your back flat as you perform the exercise. Try imagining a huge hand is pressing you down to the floor through your back. "Pull" your belly button down toward your spine.


Variations on the Crunch

Of course, working your abs doesn't begin and end with the basic crunch. By adding different versions of this tried-and-true exercise, you will be less likely to get burned out on it, you'll be able to find a format you prefer. And you'll eventually identify which bring you the results you desire (some variations are more effective than others). When you have mastered the basic crunch, try some of these below.

A study by the American Council on Exercise (ACE) found that Captain's Chair crunches, the bicycle maneuver, and ball crunches were the top three most effective ab exercises. Some variations on the crunch, such as the Captain's Chair, require gym equipment. Others can be done at home, such as the ball crunch, which is performed with the aid of an exercise ball.

Variations on the crunch include:


Don't worry about investing in a gadget from television to get your "dream abs" flattened. The ACE study found that the Ab Roller, for example, was only slightly more effective than a traditional crunch. The Ab Rocker was shown to be up to 80% less effective than a traditional crunch.


Learn More About Toning Your Abdominal Muscles

To learn more about effective abdominal exercises, see:



Anders, Mark. New Study Puts the Crunch on Ineffective Ab Exercises. Ace Fitness Matters. May/June 2001. Retrieved 5 Dec 2008.


Roth, Walton, et al. Fit & Well: Concepts and Labs in Physical Fitness and Wellness 5th Ed. Boston: McGraw-Hill College, 2002.

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