One of the hottest debates that still lingers in the fitness/rehab and sports performance industries is that over the correct use of the abdominal wall during movement and exercise. On one side, youve got the drawing-in camp that believes that the only way to safely protect your spine during exercise and movement is by drawing or sucking in your abdominal wall. This supposedly recruits what is known as the inner-unit musculature and primarily the infamous transversus abdominus muscle. On the other side, a different camp preaches the importance of using all of the abdominal layers to perform what is called bracing. By bracing one doesnt suck in or push out the abdominal wall. Instead, one just stiffens the muscles to a slight degree depending on the load or perturbation being encountered. The purpose of this article is to take a closer look at either side of this heated debate and come up with some logical conclusions based on current scientific and anecdotal research. Strap in, its going to get bumpy!

The Theory Behind Drawing-in

Well begin our tour of the abdominal universe by looking at the proposed theory of the benefits of drawing-in or bringing the belly button towards the spine. By completing such an action, the bodys inner muscular unit is supposedly activated which starts a complex process of stabilization mechanisms for the lower back, spine, and pelvis. The real impetus behind this theory stems from some physical therapy research down in Australia in the 1990s. What these researches found was that many post-injury and post-surgical patients had delayed activation of the transversus abdominus and lumbar multifidus muscles upon initiating many types of movements such as reaching for example. For the interested reader, get the book Therapeutic Exercise for Spinal Segmental Stabilization in Low Back Pain by Richardson, Jull, Hodges and Hides. In this text, the authors put forth their theories based on research of low back pain patients. The basic gist of their theory is summed up in the introduction of the above-mentioned text:

Spinal segmental stabilization is designed to specifically improve the underlying joint stabilization rather than training functional movement and hoping joint control improves concurrently

Hmmm, lets get this straight; train in an isolated way and then hope that joint control improves during functional or real-life movements and performance! Id call that a giant leap of faith based on what motor control research tells us about specificity. Try it with any healthy athlete and be prepared to be disappointed. Here are some of the reasons why this theory does not pan out in the real world:

1. Firstly, theres very little evidence that training stabilization, balance or any other motor skill in an isolated way carries over to real world type of situations that often occur under rapid or ballistic type of conditions. This goes back to the good old SAID (specific adaptation to imposed demands) principle that has been known for decades. On a similar note, balance strategies that are often encountered in sport rely more heavily on feedforward systems rather than the common gym forms of balance training that are based more on feedback systems. In discussing issues such as balance and stability these issues are important to distinguish because they are the most fundamental principles of motor learning. Feedforward systems basically are preprogrammed movement strategies in the brain. One does not have time to think, or adjust their body to accommodate the situations. Feedback systems allow one to make corrections to the movement such as in squatting, deadlifting, or pressing a weight overhead.

2. Inner-unit activation type of exercise strategies involves conscious activation of specific isolated muscles that can lead to paralysis by analysis during real life and sporting-type of situations. The old axiom of the body knowing movement not muscles comes to mind again and again. Also, it is not realistic to think that one could consciously contract their inner-unit while fighting, sprinting, changing direction at a fast speed, or performing a complex sporting skill.

3. Conscious attempt to isolate the transversus abdominus muscle can actually result in posterior rotation of the pelvis which would also cause flexion of the lumbar spine; a strategy that cannot be recommended during exercises like squats or deadlifts! This is also contradictory to most sporting movements. So, while so many argue their inner-unit is more active the structure is actually severally compromised and at higher risk for injury.

4. Fourthly, using a suspension bridge model of the spine, Canadian Spine Biomechanist Dr. Stuart McGill has shown that hollowing (drawing in) the spine causes the spine to be unstable. This is because drawing-in actually reduces the size of the base of the guy wires, which reduces the muscles contribution to spine stiffness. Ultimately, this can only lead to a decrease in spine stability.

The Theory Behind Bracing

The theory behind bracing requires much less explanation because it is much easier to visualize and understand. By bracing, one activates all the layers of the abdominal wall including the glorified inner-unit muscles. Going back to the suspension bridge model explained by McGill, during a bracing maneuver, one maintains the size of the base of the guy wires and thus increases spine stability, which reduces the tendency for spinal segments to buckle. An interesting phenomenon is that this naturally occurs in most healthy non-injured back patients when breath is held during an exertion. Its as if the body knows the kind of stability required and just unconsciously makes the person hold his or her breath. This breath holding significantly increases intra-abdominal pressure, which will be explained in greater detail below.

The role of intra-abdominal pressure (IAP) is often a forgotten component of spinal stability. In Dr. Zatsiorskys famous text Science and Practice of Strength Training, he states that even when a person leans with 80 kg weight the load on the lumbar vertebrae exceeds 1,000 kg. As we all know the body is capable of lifting far more than 80 kg. Dr. Zatsiorsky states that IAP can reduce pressure on the intervertebral disks by 20% on average and 40% in more extreme situations.

IAP can be increased by utilizing the Valsalva maneuver and by through contraction of the oblique abdominal muscles. The Valsalva maneuver is very similar to Power Breathing taught by Pavel and this is why this method of breathing should be taught to those wishing to increase stability of the body during lifting. The obliques also are vital in creating IAP along with the diaphragm. Because of the insertion points of the obliques, they can help the extensor muscles by adding stability to the erector spinae fascia. Developing strong obliques appears to be necessity for creating a stable spine. Exercises such as Janda sit-ups, suitcase deadlifts, and full contact twists fit the bill nicely.

The late Dr. Mel Siff cites some other great methods of increasing abdominal tension, Similarly, the traditional boxing technique of using punches, medicine balls, or powerful thrusts on the abdomen extrinsically increases the mechanical tension in the abdominal muscles. In other words, inward or outward distention of the abdomen during forced breath holding produces greater muscle tension and thereby offers a stronger stimulus to conditioning. No need to draw in here!

In Conclusion

In the final analysis, there is some credible science that backs up the importance of some of the deeper, stabilizing muscles of the spine and pelvis. Inner-unit activation exercises like trasversus abdominus and multifidus muscle activation techniques may have a place for initial stages of back rehabilitation. After that, they are quite limited for healthy subjects performing dynamic movements. For more integrated movements, trying to draw in may actually compromise the quality of movement and create an environment for injury as described by spine experts such as Stuart McGill.

To conclude, we believe that if you teach people the proper body mechanics (dynamic posture) for all exercises, teach proper use of the breath, and use appropriate loading strategies, most spinal injuries can be avoided. Of course, this does not account for the few unfortunate accidents that can occur during life and sport where no amount of training or conditioning is going to keep you from getting injured. We hope that this article has been informative and we would love to hear your questions and comments.