The Role of the Rectus Abdominis in Predicting and Preventing Low Back Pain

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Brendan Chapman
5 years ago
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The Role of the Rectus Abdominis in Predicting and Preventing Low Back Pain What causes low back pain?

vertebrae. These spinal nerves are complex and send efferent and afferent signals to and away from muscle and other organs.

brain called the Thalamus. When these spinal nerves exit between two vertebrae on each side of the body, it goes through an opening called the intervertebral foramen.

Again, there are many causes, but the most significant structural condition is excessive extension or hollow back (lordosis) of the lumbar (or low back) area of the

1 The Role of the Rectus Abdominis in Predicting and Preventing Low Back Pain What causes low back pain? The causes of low back pain and complicated and varied, but the pain we feel is in most cases the result of a pinching of the spinal nerve as it exits between two vertebrae. These spinal nerves are complex and send efferent and afferent signals to and away from muscle and other organs. The efferent or motor nerve sends signals to muscle that cause contraction, and the afferent or sensory nerve carries the sensation of pain back to the area of the brain called the Thalamus. When these spinal nerves exit between two vertebrae on each side of the body, it goes through an opening called the intervertebral foramen. Therefore, it is the pinching of this nerve that cause the pain sensation. The question then becomes, what causes pinching of the nerve? Again, there are many causes, but the most significant structural condition is excessive extension or hollow back (lordosis) of the lumbar (or low back) area of the spine. This will cause a compression of the spinal nerve as it exits through the intervertebral foramen resulting in pain. There are many conditions that contribute to this excessive lumbar extension. The diagram, below, illustrates a few instances where the nerve may be pinched as it exits this opening.

Herniation or bulging discs that separate the body of one vertebrae from

Certain degenerative conditions such as spondylothseis or spondylolisthesis may

These structural conditions can be diagnosed through radiographic techniques or

A significant contributor to lumbar lordosis is muscular in origin.

2 Herniation or bulging discs that separate the body of one vertebrae from another may close off the opening of the nerve as it exists or cause lordosis. Certain degenerative conditions such as spondylothseis or spondylolisthesis may pinch the nerve. These structural conditions can be diagnosed through radiographic techniques or magnetic resonance imaging (MRI). How is the Rectus Abdominis involved? A significant contributor to lumbar lordosis is muscular in origin. Even during the simple action of climbing steps or walking up a hill low back pain can occur. It may be due to a combination of muscular imbalances and requires a careful and in depth discussion of two muscle groups. First of all, you need to know that taking any step in a forward direction requires that you raise you knee.

This action at the hip is called flexion.

This Psoas actually crosses two joints: the hip and the lower part of the spinal column called the lumbar

Every time this muscle contracts it not only causes the hip to flex (raise the knee forward), but it also

foramen resulting in a pinching or compression of the nerve.

3 This action at the hip is called flexion. One of the muscles that allows you to perform this flexion is called the Psoas. This Psoas actually crosses two joints: the hip and the lower part of the spinal column called the lumbar vertebrae. Every time this muscle contracts it not only causes the hip to flex (raise the knee forward), but it also pulls on its attachment at the vertebra (called the transverse process) to cause extension of the lower back (lumbar area). Excessive extension of the lumbar area results in lordosis which closes off the opening at the intervertebral foramen resulting in a pinching or compression of the nerve. Unfortunately, the Psoas does not have a brain and doesn't know that it should only perform the useful action of flexion at the hip and not extension at the lumbar vertebrae. In order to prevent the Psoas from performing the undesired action of lumbar extension, we need to push the lumbar area backward (posterior tilt) to flatten this section of the vertebra and maintain proper posture. The Rectus Abdominis is in the best anatomical position to do this.

The lower portion of the Rectus Abdominis attaches to the top of the pelvis (pubic symphysis) and the upper part connects to the lower part of the breast bone (xyphoid process) and associated ribs.

Since the back of the pelvis is directly attached to the lower part of the vertebrae, when the pelvis is pulled backward (posteriorly) this cause the lumbar portion of the vertebra to flatten,

Xyphoid Process Pubic Symphysis The Rectus Abdominis is the major muscle needed to prevent lordosis and pinching of the spinal nerve as it exits the intervertebral foramen.

Specifically, when you attempt to lift a package form a stooped position, or raise your leg climbing up stairs (hip flexion), there is a natural tendency for the Psoas muscle to cause lumbar

4 The lower portion of the Rectus Abdominis attaches to the top of the pelvis (pubic symphysis) and the upper part connects to the lower part of the breast bone (xyphoid process) and associated ribs. This allows the muscle to draw the pelvis backward (posterior tilt). Since the back of the pelvis is directly attached to the lower part of the vertebrae, when the pelvis is pulled backward (posteriorly) this cause the lumbar portion of the vertebra to flatten, reducing the lordotic curve. Xyphoid Process Pubic Symphysis The Rectus Abdominis is the major muscle needed to prevent lordosis and pinching of the spinal nerve as it exits the intervertebral foramen. If you followed this logic so far, you can see that a weak Rectus Abdominis has the opposite effect. Specifically, when you attempt to lift a package form a stooped position, or raise your leg climbing up stairs (hip flexion), there is a natural tendency for the Psoas muscle to cause lumbar extension (beyond the normal it is called lumbar hyperextension). If your Rectus Abdominis is not sufficiently developed (not for repetition but for strength), then there will be nothing to oppose the lumbar hyperextension which occurs even during simple tasks. Athletes are particular susceptible to lumbar hyperextension because of all the forces applied during running, jumping, collisions (offensive vs. defensive lineman), etc. The list goes on and on. Also, individuals sitting for long periods of time tend to create that extra arch in the back or lumbar lordosis. It is no wonder that a recent survey found that 45% of bank employees sitting at their desks have low back pain.

5 Are other muscles involved? Looking forward! Of course. The answer in preventing low back pain (when there are no structural abnormalities present) goes beyond measuring and strengthening the Rectus Abdominis. The other abdominal muscles also play a significant role such as the internal and external olbiques abdominis and the transversus abdominis. In addition, several of the muscles on the back (Erector Spinae, Multifidus) as well as some of the muscle underlying the floor of the pelvis play a role. We are in the process of expanding upon our testing protocol to include the back extensors and also looking at the ability to stretch the back muscles (increase range of motion of lumbar flexion) as contributing factors in low back pain etiology. Our Core routines are designed to strengthen most of the muscles surrounding the mid-section in a manner that stabilizes the vertebrae rather than place unnatural and excessive stain on these structures. It is also predesigned to use progressive resistance with different starting points based upon initial strength levels. Therefore, individuals who train with Core may be placed into a beginner, intermediate or advanced group.

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