Rectus Abdominis Myths
Defending the Misunderstood Six-Pack Muscles in Mind & Body Exercise
May 18, 2009
Among some groups, the rectus abdominis muscles are prized for the attractive "washboard" appearance they give to the abdomen. These muscles can be effectively trained with situps and crunches. Bodybuilders maximise their appearance by reducing bodyfat so that the horizontal grooves that separate each section of the muscles are clearly visible. It's common for exercisers to regard the rectus abdominis muscles as by far the biggest and most important muscles of the abdomen.
Among some bodyworkers and mind-body exercise teachers, however, the rectus abdominis gets a bad rap. Contemporary Pilates, especially, emphasises the transversus abdominis (TvA), a corset- or belt-like muscle that wraps around the torso. These teachers rightly emphasise the array of muscles that make up the abdomen - TvA, internal and external obliques, and rectus abdominis, as well as smaller muscles like the pyramidalis and related muscles like the psoas, diaphragm, deep pelvic floor muscles, multifidus, and erector spinae. This can mean, though, that they regard rectus abdominis as unworthy of attention.
Consider some of these prevalent myths:
Rectus Abdominis is the Biggest Abdominal Muscle
No - external oblique, wrapping around the torso, is larger than the rectus abdominis. The paired six-pack muscles are actually quite narrow.
Rectus Abdominis is the Most Superficial Abdominal Muscle
Considered fascially, since rectus abdominis lives snuggled in the sheath of the obliques and TvA, it's never the most superficial. External oblique's aponeurosis (its flat, sheetlike tendon, covering the front of the abdomen) is superficial to the rectus abdominis, and internal oblique splits its aponeurosis like a fillet to encase rectus abdominis in front and back.
An inch or so down from the navel (inferior to the arcuate line), rectus abdominis dives deep to all three of the other ab muscles' aponeuroses, where it meets the deep pelvic floor at the pubic bones.
Rectus Abdominis Does Nothing But Flex the Spine
Its primary action is flexion, but rectus abdominis also assists in sidebending the spine. Further, it is the only abdominal muscle that tenses the linea alba (the "white line" of tendon that runs down the centre of the abdomen, dividing the rectus abdominis into two strips) rather than pulling it apart.
Rectus Abdominis is a Show-Off Muscle
Like every muscle in the body, rectus abdominis has a purpose. As part of a line of muscle beginning at the tailbone (as the pubococcygeus, a deep pelvic floor muscle) and continuing to the sternum and beyond, rectus abdominis plays an important role in supporting the torso. While it should be used in balance with other muscles, its significance shouldn't be ignored.
Rectus Abdominis Forms the Upper Abs; Transversus Abdominis is Down Lower
This common misconception confuses the location of the abdominal muscles. Rectus abdominis runs from the ribs and sternum, right at the top of the abdomen, all the way down to the pubic bones. The obliques and TvA, similarly, are attached to the ribs at the top and the pelvis at the bottom. Though the upper portion of rectus abdominis is easily visible when it is well-developed, the muscle is equally present at the lowest part of the abdomen.
Mind-body exercise teachers and bodyworkers, and their students, should be careful to give the rectus abdominis the attention and respect it deserves as a vital part of the musculature of the torso.
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