the ab crunch: looks, form and function
the rectus abdominis, or "abs,"...
are the muscles many of us would like people to see when in a bathing suit. And besides the aesthetics aspect, they are also an important muscle group for function. The ab crunch machine trains the abs as well as another pair of important muscles. However, performing this exercise requires attention to detail. There is a small difference between proper execution and lower back strain with the ab crunch. In this article, we’ll discuss all of those details.
The rectus abdominis starts at the bottom of the sternum (chest bone) and the front of the ribs in that area. It runs down to the top of your pubic bone (part of the pelvic girdle), which is just above your genitals. The main function of this muscle is to pull your spine into a ‘C’ shape, bringing your chest and midsection closer together.
Of course, the abs are most known because of the “six pack.” A “six pack” has that appearance because of connective tissue. As the abs flow from the ribs to the pelvic girdle, there are three segments of connective tissue in the middle. This where the “six pack” gets its upper, middle, and lower portions. Also, a sheet of connective tissue (linea alba) runs vertically, splitting the abs in half, causing the appearance of six muscles as opposed to three. Secondary muscles in the ab crunch are the external and internal obliques. The obliques are located in the area that many refer to as their “love handles.” (We’re covering all of the fun stuff today.)
Performing the ab crunch regularly to the muscle exhaustion point of “muscle success” will help your abs and obliques become stronger and more aesthetically noticeable. However, I have to warn you: Seeing your midsection muscles is largely a result of low body fat levels. The less fat between your skin and your abdominal muscles, the easier it is to see definition in your abs. And losing body fat is mainly a result of positive dietary changes. Your desire to see your abs may beckon a change to your diet even more than the use of the ab crunch machine.
Believe it or not, the rectus abdominis does not exist only to make you look good in a bathing suit. It is also functionally significant. The abs are critical muscles for respiration and child birth. In addition, they are major stabilization muscles. In regards to stabilization, every exercise or sports movement focuses on a small group of joints. For example, throwing a baseball mainly involves the elbow and shoulder joints. For this to occur with optimal efficiency and effectiveness, muscles in various parts of the body contract to hold other parts of your body relatively still. Your abs are one of the most common and important stabilization muscles.
I mentioned previously that the abs work to pull your chest and midsection closer together, causing your spine to curl into a ‘C’ shape. The proper range of motion for the ab crunch is small compared to most exercises. The exercise may include only four or five inches of movement in each direction. It’s common to exceed this amount, and that’s where some problems occur.
In the ab crunch, as you “curl” downward, your lower back should press into the lower pad. (Your upper back should stay firmly pressed into the upper pad also.) If your lower back is about to peel off the pad, this is a cue that you’re at the end of the range of motion, and need to reverse direction and begin returning to the starting position.
When the lower back is removed from the pad, the midsection and thighs are now moving closer together. This motion is a hip-based movement called “hip flexion.” Hip flexion uses other muscle groups, and these muscle groups exert some force on the lower back. Examples of exercises that use hip flexion are sit-ups and leg lifts. While the abs assist in these exercises, the hip flexors are the dominant muscles.
In summary, “curl” down on the ab crunch machine no further than the point where you feel your lower back will start leaving the back pad. Using the ab crunch will strengthen your abs and obliques, muscles that not only make you look good on the beach but also help with critical life functions.
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