The most frequent exercise and anatomy questions I get tend to revolve around the abdominals. Of course they do! We all want flatter, more defined abs and a trimmer waistline.
You're already obsessed with abs - now here's one of the biggest pieces of info you'll need to make the most of any abdominal workout you choose to pursue. So you can work smarter as you work hard!
Concentrate on the DEEPEST LAYER of ab muscle: the Transversus Abdominis
What is it?
Note: “transverse” and “transversus” abdominis are both used with equal accuracy and frequency. It just depends on who you’re talking to or which book you’re reading. For the sake of this article, we will call it the transversus abdominis.
The deepest of the muscles that make up the “abdominal wall,” the transversus abdominis is often neglected and misunderstood. Yet, it is necessary to engage this muscle to help promote efficiency of movement and protect the spine.
The muscle fibers run horizontally (part of the muscle is shaded in bright red in the image to the right); when the transversus contracts, it tightens around the abdominal organs in a “corset-like” manner, cinching in the waistline. Unlike the other primary abdominal and spinal muscles, this internal corset doesn’t mobilize any joints or the spine on its own – it stabilizes the spine in any given position. The easiest way to access proper transversus abdominal engagement, however, is by stabilizing the spine in a neutral position (ideal curvature of the spine intact) such as a well-executed plank. Basically, engagement of this large and deep muscle supports the engagement of any of the other abdominal muscles. So, when the spine is mobilized, it is supported with the strength of at least two muscles instead of only one. This makes a huge difference in quality of movement as well as preventing injury of the back!
For your reference, note that the muscles of the abdominal wall are as follows: rectus abdomins (closest to the skin); the next deepest layer is made up of the external obliques; one layer deeper lie the internal obliques; deepest of all is the transversus abdominis.
In this image, the right side indicates the deepest layer and most superficial layer, while the left side indicates the intermediate layers.
For those feeling extra-nerdy -
Four points of origin: lateral inguinal ligament, iliac crest, thoracolumbar fascia, and internal surface of the lower 6 ribs.
Insertion: abdominal aponeurosis to linea alba
How do I find it?
At first, it can be difficult to feel the engagement of this abdominal muscle, and it can be even be challenging for a fitness instructor to describe it to clients. Many instructors say to “lace up your corset muscles,” or “pull your belly button to your spine,” and these can be helpful. However, some effort should also be made to “pull in” the muscle fibers two inches below the belly button. This is also part of the transversus abdominis, and the tightening of these fibers will help support the vulnerable lumbar spine while helping to prevent over-engagement of the quadratus lumborum (muscles in the lower back that are often over-used and tight). Once proper engagement is achieved, you will notice that the other abdominal muscles have engaged as a result of accessing the transversus abdominis – THIS is efficient muscle recruitment for abdominal exertion.
Be mindful that you don't simply “suck the belly in,” as this is not an action that promotes proper breath patterns or even one that triggers proper abdominal engagement at all. Instead, integrate the idea of “pulling” or “cinching” the abs in, and pulling the spot two inches below your navel “in and up” to promote the sought-after “abdominal scoop,” which demonstrates ideal transversus abdominal engagement. The belly should never "pop out" significantly during abdominal work (though skin may fold on itself when curving the spine forward, I'm referring to the muscles pouching outward). Aim for a belly that is curving inward toward the spine, and the result will be a significant flattening of the abdominal wall - which will make your body and your ego very happy!
Optional exercise to access transversus abdominis activation: to find proper transversus abdominis engagement, take a big inhale into the lungs and belly. Begin exhaling. When you think all the air has been expelled, force out a little more breath. You’ll notice how your waist cinches in and your lower abdominal fibers tighten and feel as though they are pulling slightly upward. This is your transversus abdominis. Inhale again, but this time, hold your breath for a moment. Consciously replicate that engagement now to INITIATE your exhale. Now you can choose to engage your deepest abdominal muscle fibers regardless of what movement your body is doing.