A Scientific Look at Abdominal Exercises

It is safe to say that there is such a thing as an ab exercise obsession. Abdominal exercise videos and books are usually bestsellers. Pilates classes continue to be popular largely because of the emphasis on shaping and firming the abs and waist. Any class advertised as an “abs class” is sure to be well attended.

However, there are also ab exercise misconceptions. Scientific studies have helped to cast a clearer picture of what is true or false. Here’s what research has uncovered.

Upper and lower abs
The rectus abdominis is the straight muscle in the middle of your abdomen. It is the only abdominal muscle that can hypertrophy or become bigger. You guessed it, its also known as the “six-pack” muscle.

Technically speaking, you cannot work the upper and lower rectus muscles independently. Research has found that when you do a crunch (lifting the upper body), you will “feel” the exercise more in the upper abdomen because there is more shortening of the muscle fibers in that area. However, the muscle fibers in the lower abdomen are also shortening only not as much as the upper region.

When you do a reverse curl (curling the hips), you will “feel” the effort more in the lower abdomen even though the muscle fibers in the upper abs are also working.

If you stick your hands into your jeans pockets in front, your hands are forming a “V” shape or the direction of the external oblique muscles. If you turn the pockets inside-out, your hands are now forming an upside-down “V” shape or the orientation of the internal oblique muscles.

The external obliques are located in front but the internal obliques wrap around the waist and attach to a diamond shaped connective tissue in the lower back region.

Many people think that the obliques are only worked if you do twists or abdominal exercises with rotation but they also contract when you do crunches and reverse curls. When you do a reverse curl, the external obliques are more active.

When you do a crunch, the internal obliques are more involved. When the internal obliques are strong, they support the middle of the torso like a tight corset. This is the scientific explanation of why crunches can help strengthen the lower back.

Spot reduction
Many people believe that abdominal exercises by themselves will lessen the amount of fat they have in the abdomen. But “spot reduction” or the belief that specific localized exercises will reduce the fat on top of the working muscles has already been disproved as far back as 1971when researchers showed that the dominant arm of tennis players had the same amount of fat as the non-dominant arm.

In a 1984 study at the University of Massachusetts, male participants did the equivalent of 5,000 sit-ups for 27 days. Fat was measured in the abdomen, buttocks and upper back. According to the spot reduction theory, fat should have been reduced only in the abdominal area because the buttocks and upper back are not actively involved in doing a sit-up. Researchers found that fat was reduced in all three areas but only very slightly (or as scientists like to say, “Not significantly”). There was no real change in the thickness of abdominal subcutaneous fat (read: bilbil) or abdominal girth. Fat biopsies showed there was no significant change in the diameter of abdominal fat cells either.

Abdominal exercises can partly help you attain a flatter stomach and smaller waist by strengthening and firming up flabby muscles. To reduce the overlying fat, you have to lose total body fat by doing aerobic exercise and resistance training, eating a sensible diet, and living an active lifestyle.

To read a more in-depth article I have written on spot reduction, go to http://www.tinajuanfitness.info/articles/art070803.html

Abs Q & A
Here are answers to common questions about abdominal exercises (based on a lecture by Dr. Len Kravitz). For the complete report, go to http://www.unm.edu/~lkravitz/Article%20folder/abdominal.html
· What is the best exercise to train the abs? There is no single abdominal exercise that challenges all the abdominal musculature, thus requiring the prescription of more than one single exercise.
· Is it okay to use resistance with abdominal training? Definitely, to create more tension. But only after mastering the proper technique without resistance.
· Is there an ideal sequence in working the abdominal muscles? No, because you should use a multi-stimuli approach.
· How high should you go up in a crunch? Crunch height is about 30 to 45 degrees depending on the length of the torso. Basically, it’s the point at which the shoulder blades come off the floor.
· Should you do ab exercises daily or three times a week? Currently, there is no single study showing a greater benefit in doing the exercises daily or several times a week.
· Should you pull the abs in while doing abdominal exercises? Yes, to activate the transverses abdominis (TVA), which is the deepest abdominal muscle. It has horizontal fibers, which are the foundation for all the other fibers to attach to. The TVA wraps around to attach to the same connective tissue in the lower back area that the internal obliques attach to.

Researcher Michele Olson presented the results of a Pilates study at the 2005 American College of Sports Medicine convention. Here’s an excerpt from the ACSM news release.

“In another phase of the study, the team measured abdominal muscle activity during key Pilates mat exercises. Participants performed five Pilates “ab” exercises, then basic crunches for comparison.

“Results showed that the rectus abdominis muscle, which runs along the mid section of abdomen, was challenged similarly for most of the Pilates exercises. However, the Teaser exercise and Roll-Up challenged this abdominal muscle more than the crunch.

“The external obliques, the muscles on either side of the abdomen, were challenged to a greater degree by all of the Pilates exercises compared to the basic crunch.

“In particular, the Criss-Cross was the most effective for the external obliques. However, the Teaser exercise also activated the hip flexors to a marked degree. Thus, this exercise may be best reserved for very advanced individuals or athletes.”

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