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Abdominal muscles


Three groups of muscles make up the abdominal region:
  • Rectus abdominis. The rectus abdominis muscle, also known as the "abdominal muscle", is the most visible muscle of the abdomen. It is a paired muscle running vertically on each side of the anterior wall of the abdomen. There are two parallel muscles, separated by a midline band of connective tissue called the linea alba. It is often referred to as the main core of the "abs" and consists of the muscles that form the "six-pack."
  • External obliques. The external oblique is situated on the lateral and anterior parts of the abdomen. It is broad, thin, and irregularly quadrilateral, its muscular portion occupying the side, its aponeurosis the anterior wall of the abdomen. In most humans (especially females), the oblique is not visible, due to subcutaneous fat deposits and the small size of the muscle.
  • Intercostals. The intercostal muscles are several groups of muscles that run between the ribs and help form and move the chest wall. The intercostal muscles are mainly involved in the mechanical aspect of breathing. These muscles help expand and shrink the size of the chest cavity to facilitate breathing.


To develop your midsection, you need to work all three muscle groups. When performing all ab exercises, focus the tension on the abs without cheating by using body momentum to bounce into the movements. Always squeeze the abs for a few seconds during the tension element of an exercise before releasing the tension.

No ab exercise will remove the layer of fat over the abdomen. Exercising a specific area of the body may make it stronger but it will not burn fat from the specific area. The body burns fat generally, not locally. The only way to remove fat is by using diet and calorie-burning aerobic exercises. Without losing fat from the abdomen this way, the ab exercises may make your abdomen look even larger since the stronger muscle wall may push the fat outward.

The stomach muscles become visible at about 10 percent body fat and become pronounced at about 6 percent body fat, but most men and women cannot maintain 6 percent body fat for very long. Attaining a "six-pack" abdomen requires hard work plus the proper genetic make-up. Without the genes, you may still improve your appearance, but six-packs are out.

Secrets to a flat belly

The anterior pelvic tilt is a posture in which your upper pelvis tilts forward, pushing your abdomen outward. This raises your risk of lower back pain and makes your abdomen look fatter. A combination of imbalanced training, such as bending but not extending, and neglecting certain muscle groups often cause this condition.

To shift the pelvis back and flatten your belly, focus on your core with rotation exercises, such as medicine ball twists. Strengthen your hip flexors with a kneeling hip flexor stretch so the flexors will have the strength to move your hips back toward your abdomen. Strengthen your hamstring and glutes with hip raises so they can help pull your pelvis back to its natural position.
Best abdominal exercises

An American Council on Exercise (ACE) study used electromyography equipment to measure electrical activity generated as muscles work to measure the energy created in specific abdominal muscles (mainly the rectus abdominus muscles—the six-pact muscles). Study participants performed 13 types of ab workouts, some with equipment, some without. The traditional crunch-style sit-up was used as a baseline for the ratings.

The study found the following:
  • The top-rated exercise was the bicycle exercise where you lie on the floor on your back, knees raised, and then move your legs as if riding a bicycle. This exercise was 250-percent better than the crunch.
  • The second-rated exercise was called the captain's chair. This exercise is done on two parallel bars that permit you to rest your weight on your forearms with the feet off the floor. The knees are then drawn up the chest and lowered. This exercise was 212-percent better than the crunch.
  • The third-rated exercise is sit-ups done while lying back on a large squishy exercise ball. This exercise was only 39-percent better than the crunch.
Exercises using equipment were ineffective. For example, the Body by Jake Ab Roller was only 5 percent better than the crunch. The AB Rocker was 21 percent WORSE than the crunch.


  • American Council on Exercise (ACE) May-June 2001 Supplement to Fitness Matters.
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