for more than just a six pack: get to know the ab crunch
Jordan Thomson CPT
Updated 05/05/23
The Ab Crunch is a client favorite when it comes to exercises.
Sometimes it’s because of a misconception about what it can do for belly fat.
Other times, it’s because clients know how it can help their mobility goals.
Let’s dig into what the Ab Crunch can do for you…
Muscles Used
The rectus abdominis, or “abs,” are the muscles many of us would like to display in a bathing suit. Besides the aesthetics, they’re 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’s a small difference between proper execution and lower back strain with the ab crunch. We’ll discuss all of those details later in the article.
The rectus abdominis starts at the bottom of the sternum (chest bone) and the front of the ribs. 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 and causing it to look like there are six muscles instead of 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.) 😉
How It Works
Regularly performing the ab crunch to the exhaustion point of “muscle success” will strengthen your abs and obliques and possibly make them 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. Wanting to see your abs may beckon a change to your diet 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 childbirth.
In addition, they are major stabilization muscles.
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 (like your abdominals!) contract to hold other parts of your body relatively still.
Performing the exercise looks like this:
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.
To avoid overextension problems that can lead to discomfort or targeting the wrong areas, follow these simple steps:
- In the ab crunch, as you “curl” downward, your lower back should press into the lower pad. (Your upper back should also stay firmly pressed into the upper pad.)
- 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 help you look good on the beach (with proper nutrition) but also with critical life functions.
Maximize Your Ab Crunch in 2 Minutes or Less
In order to get the most out of your 1-2 minutes on the Ab Crunch, your coach will guide you through these four things:
- Full Range of Motion (and no further!): Full range of motion helps avoid shortcutting the targeted muscles. Think “ribs to hips” and “belly button to spine” to squeeze your abdominal muscles properly.
- Relax Your Feet and Hands: Avoid letting your hands or feet take over carrying the weight to “muscle through” the movement. You want the primary contraction to live in your abdominals. The goal isn’t to get as far as you can. It’s to let the targeted muscles reach muscle success.
- Neck Relaxed: Try to keep the neck as static and relaxed as you can to keep the tension in your abdominal muscles and not in your neck.
- Muscle Success: How could we leave this out?! Achieve muscle success and thoroughly fatigue your abdominal muscles to help build your strength.
Strengthen your abdominal muscles and work toward visible abs with a 20-minute workout.
