Say No to Crunches
In this article we are going to discuss the anterior core. Now, there are whole textbooks devoted to just core muscles, their function or dysfunction and strategies to strengthen and rehabilitate. This will just barely scratch the surface of what science knows about the “core” and every day there is more information being learned about its vital function.
However, this very brief overview will help to give you a glimpse of what the anterior core muscles are all about, why we are selective in our training of these muscles and also why we are always looking for better and safer ways to make these muscles not only stronger but more “functional”.
When I look back on the last 10 years that I have been training clients, I am amazed how my training programs have changed. As I read and learn, things change. That is what is so exciting about the field of human movement and how it relates to keeping us all healthy and strong. Even those of you that have been training at Victoria Wellness for a short time will notice changes in our training selection. And, as I continue to learn, things in the gym will continue to change. As long as there is science to support the change, I am willing to entertain it.
Now onto some core work shall we? The anterior core consists of several muscle groups. In this article we are not going to discuss hip musculature that is involved with the anterior core muscles nor are we going to discuss the “back side” of the core (the posterior chain). Just understand that no muscle or group of muscles work in isolation so there is interaction between all muscles to create movement and prevent movement, as well as control joint stability.
We are going to talk only about the rectus abdominis, internal and external obliques and the transverse abdominus.
Rectus Abdominis: this muscle originates from the pubic crest. Its fibers runs vertically and insert onto the 5th, 6th, and 7th ribs as well as to the sternum. The action of this muscle is to flex the vertebral column and tilt the pelvis posteriorily.
The rectus abdominis in conjunction with the obliques is responsible for control of trunk and pelvic rotation during movement. If this muscle becomes dominant (which can happen with doing old fashioned crunches and situps), and the obliques are not conditioned, control of the trunk and pelvis is weak. This will lead to low back pain and possibly serious injury.
When the rectus muscle is overworked with crunches and sit ups it can pull the chest down and cause a rounding of the upper back leading to kyphosis. Just one more reason that crunches and sit ups are not an exercise of choice.
External & Internal Obliques: the external obliques originate on the rib cage and insert into the pelvis and the rectus abdominis on the front abdominal wall.. The internal obliques originate on the pelvis and insert into the rib cage and the rectus abdominis. The internal oblique muscles run perpendicular to the external obliques.
The external oblique muscle controls or prevents anterior pelvic tilt and along with the internal oblique muscles control lateral pelvic tilt.
Transverse abdominus: this muscle originates on the inner surfaces of the lower six ribs, the thoracolumbar fascia (of the lower back), the iliac crest and the inguinal ligament. Its fibers run transversely and insert into the linea alba on the from abdominal wall, pubic crest and pecten pubis. In other words, these muscles run around our trunk like a belt.
The action of this muscle is to flatten the abdominal wall and compress the abdominal contents. Because of its attachment to the thoracolumbar fascia in the lower back, it contributes to the stability of the lumbar spine. You want a flat looking stomach? Then work on controlling this muscle.
This is the first muscle recruited for postural stabilization during movements of the upper or lower extremity. In other words when we start to move, this muscle engages and holds our lumbar spine stable.
The primary function of the abdominal muscles is to provide isometric support and limit the degree of rotation of the trunk. Because the lumbar spine is not intended to rotate, a large percentage of back problems occur because the abdominal muscles are not keeping a tight control over the rotation between the pelvis and the spine.
In other words, the abdominal muscles are there for support, not to flex. They are there to restrict rotation of the lumbar spine (lower back). The job is isometric in nature (without movement).
So, in closing, I hope this helps explain why we do not do crunches or situps. Please re-read the previous paragraph and it will help you to understand why the staple of our core training is planks, side planks, supermans or birddogs, roll outs and various chop motions.
Was there a time when I did sit ups and crunches? Yes, there was – hundreds and hundreds of them. But as I have learned, the exercise programming has changed. Stay tuned, I am sure there will more change to come.
Till next time,
“Monitoring, Mentoring, Motivation”
Source: Diagnosis and Treatment of Movement Impairment Syndromes, Shirley A. Sahrmann, PhD