Your rectus abdominus, commonly known as your ‘6 Pack’, has another more interesting function than those discussed in Part 1 (read my post on why your abs are important, Part 1) of this series of articles on this muscle.
Considering that the most common exercise we perform to strengthen our ‘6 Pack’ is the sit up (read my post on sit ups and lower back pain), it’s not surprising that we think the main function of this muscle is to bend ourselves double. Few of us are though are gymnasts, thus we don’t normally use this muscle for bending our trunks, unless we’re performing situps or pikes in the gym (and if you’re picking up objects in this manner, please stop, you’re going to injure your back – another topic I’ll post about in the future). In other words, bending our trunks is not the every day way in which we use this muscle in our daily lives.
What then is the more important function of the rectus abdominus (‘6 Pack’) in our lives? To understand more, we need to have another look at how this muscle is built.
The ‘6 Pack’ is a long muscle that extends from the lower few ribs and inserts into the top of the pelvis. Because we think of it as a long muscle, we think of its main function as bending us in half. What we forget, however, is that the muscle is ‘tethered down’ by tendinous tissue giving us the ‘6 Pack’ distinctive look (when it’s not covered by blubber as mine currently is).
The important effect of these tendinous tethers along the length of the rectus abdominus is that, far more important than making your abdominal area look really ‘fit’, these tethers create stored spring like (elastic) energy in the abdominal area when you contract this muscle.
The stored elastic energy that is created when you contract your rectus abdominus is helpful in many ways during everyday life. Firstly, it helps increase our intra-abdominal pressure, which is important in coughing, vomiting and emptying our bowel and bladder. People who have been extremely unfortunate to suffer a spinal injury and no longer have function of their rectus abdominus (‘6 Pack’) can testify to how difficult it is to cough or forcefully exhale without this muscle’s function. They often have to resort to external means such as leaning forwards or using their arms to press into their abdominal area to help replicate the function that our rectus abdominus normally performs for us.
It’s also important to understand that you don’t need to bend over to contract this muscle. We are all able to contract our rectus abdominus while remaining upright. This type of static contraction is called an isometric contraction.
In terms of sport and exercise though, this elastic energy also adds force and power to movements that occur at our hips or shoulders in activities such as throwing something (e.g. javelin throwing) or tennis serving or springing forwards as a sprinter and many many more examples.
The next question to ask then is, how am I training this muscle? Am I training it in a one dimensional capacity (e.g. performing sit ups or pikes), or am I training it in a functional way that will enhance my sporting performance. Remember: what you train, is what you get!
McGill S. (2010). Core Training: Evidence Translating to Better Performance and Injury Prevention. Strength and Conditioning Journal, 32 (3), 33-46.