Date: Wed, 26 Mar 1997 From: Paul Chek Subject: Interactive Functions of the Abdominal Wall During Sports and the Squat Exercise FUNCTIONAL INTERACTIONS OF THE ABDOMINAL WALL DURING SPORTS AND THE SQUAT EXERCISE There is clearly an information gap between what is known by anatomists and elite rehabilitation specialists and what is known by the exercise profession at large. Training the abdominal musculature from a flat surface forward in the supine position has little, if any carryover to function be it lifting at the home or work or stabilization during most sports situations. The standard crunch is complete within 30 deg. Trunk flexion and takes place anterior to the mid-frontal plane. The abdominal musculatures are active as both prime movers and stabilizers through 45-80 degrees extension behind the mid-frontal plane (1). This is an important fact because many spine injuries occur in positions of extension and rotation - the position that closes neural foramina and encroaches upon nerve roots. This extension-rotation position is very common in most contact sports. Additionally, it is from a position of spinal extension that most all implements in sports (baseball, football, javelin, volleyball, etc.) are accelerated from. The abdominal wall has segmental innervation, sources arriving from T5-L1. Consider that these muscles are under the control of nerves, were most muscles have one primary and one secondary source of innervatioin. This would be analogous to a person with nine brains; such a person could carryout many tasks at once! The fact is that the abdominal wall performs both stabilizer, neutralizer, and prime mover functions at any given time. The functions of the abdominal wall during a squat are completely different than during running, swinging a bat or hockey stick. During the squat, the abdominal was functions in concert with the diaphragm as a stabilizer of the torso. The stabilizer muscles of the abdominal wall are: Transverse Abdominus, Internal Oblique, and in many postural instances the External Oblique musculature. Unfortunately, the rectus abdominus is frequently recruited as a stabilizer do to overexposure to upper abdominal dominant exercises. The rectus abdominus is a powerful flexor of the trunk; activating the rectus abdominus during a squat serves to increase the flexion moment on the spine. As described by Bogduk and Twomey (2), the transverse abdominus and internal oblique have a unique relationship with the thoraco-lumbar fascia. Proper activation of these musculature creates hoop tension, causing a traction force on the connective tissue slips of the deep layer of the superficial laminae of the thoraco-lumbar fascia, which when combined by activation of the latissimus dorsi, creates an extension moment on the lumbar spine. This extension moment serves to counterbalance any flexion forces created by activation of the abdominal mechanism, which then serves to stabilize the trunk and lumbar spine, in concert with the intra-abdominal pressure mechanism. The intra-abdominal pressure mechanism utilizes the same hoop tension to compress the viscera. This compression drives the viscera upward into the diaphragm and downward into the pelvic basin (which hopefully seals). As the viscera are driven into the large surface area of the diaphragm, the squatter is holding a Valsalva or partial Valsalva (I hope?), which tenses the diaphragm. The rising viscera meet the resistance of the diaphragm. This places tension upon the cura of the diaphragm which cause a lifting, or decompression force at the L2-L3 levels. This decompression force is said to be between 30% (3) and 6% (4). Because the experienced lifter attempts to maintain a lordotic lifting posture, the Hydraulic Amplifier mechanism will also come into play. This mechanism is dependent upon expansion of the spinal erectors within the fascial envelope; as they expand within the envelope, there exists an erectile force. It must be understood that all stabilizer mechanisms of the spinal column are dependent upon a functional abdominal wall. No one abdominal mechanism functions without the other (5). Weight belts, inhibit the abdominal wall's ability to create hoop tension because the belt performs the function mechanically. This results in a progressive detraining of the abdominal wall, which can have serious implications for those having to lift heavy objects outside the gym environment or for those who forget their belt and lift anyway! A measure of functional deficit in the abdominal wall secondary to belt use can be determined by simply calculating what can be lifted without the belt vs. with the belt. You may get a big surprise if you're an avid belt user! If your abdominal wall flexes and thickens as you squat, you are attempting to use the rectus abdominus to stabilize, which will actually destabilize. When the abdominal wall functions correctly, the transverse abdominus and internal oblique contract, creating hoop tension to activate the intra-abdominal pressure mechanism, thoraco-lumbar fascia gain mechanism and stabilize the fascial envelope for optimal activation of the hydraulic amplifier mechanism. Proper abdominal wall function during squatting or lifting is signified by a" drawing in" of the abdominal wall, not a thickening as seen with activation of the rectus abdominus. Use of weight belts encourages rectus abdominus activation because the lifter attempts to drive the abdominal wall into the belt, in attempt to create more pressure. If fact, Eric Burkhardt stated what is so common amongst lifters "I placed my hand on my upper abdominals at the bottom of a Good Morning and they felt hard." This is a brief summary of a very complex topic (5). Paul Chek, MSS, HHP, NMT Paul Chek Seminars www.paulchekseminars.com Ph. 619-551-8789 References: 1. Paul Chek Scientific Back Training Correspondence Course Paul Chek Seminars Ph. 1-800-552-8789 or 619-551-8789 2. N. Bogduk and L. T. Twomey Clinical Anatomy of the Lumbar Spine Churchill Livingstone, 1991 3. Rolf Wirhed Athletic Ability and the Anatomy of Motion Wolfe Medical Pub. 1984 4. Serge Gracovetsky The Spinal Engine Springer-Verlag - New York, 1988 5. Paul Chek Scientific Abdominal Training Correspondence Course Paul Chek Seminars ------------------------------ Date: Tue, 25 Mar 1997 From: joshua peter kirk Subject: Re: Squat specific abdominal training Good subject and questions Eric! Here is what I think, it would be nice to find some research to back it up. In addition to providing stabilization for the spine I see the role of the abdominals as two fold. It first acts as limiter to forward pelvic tilt, and then it reverses this motion during different parts of the lift. Yes, the pelvis must tilt forward to maintain lumbar lordosis. However, I believe that most of the problems that occur in the bottom position have to do with excessive anterior tilt. This can cause a lean forward, an increased moment arm, loss of balance, and a missed lift. Consider the insertion point of the abdominals on the anterior distal pelvis. It is close to the pubic crest on the ischium. As you descend to the bottom position tight abs will create a trap for the pelvis as it tilts forward. Now consider the hamstring and gluteal attachments on the distal posterior side of the pelvis. From a forward tilt position in the bottom of a squat the hamstrings will contract, extend the hip with a closed foot, and rotate the pelvis backwards. From the anterior the abdominals will contract against a fixed rib cage. In addition to stabilization at this point it seems the abs may slightly rotate the pelvis backwards rising out of the bottom position, helping to reverse the forward tilt that occurred on the way down. :From experience in my own training, if I worked my abs heavy the day before squatted I was sure to get squashed in the bottom position even though my leg strength was optimal. Some of this was probably due to inability to maintain abdominal compression, but I think there is more to it than that. I do feel a conscious isometric contraction of the abs when I am in the ready position (with my chest high and pelvis rotated forward with a slightly exaggerated lumbar curve), and as I lower through the lift I maintain this tightness. Do I feel them contract coming out of the bottom position? I feel everything contract at this point so its hard to tell. However, I do feel them contract as I lock out a squat, throwing my hips forward, attaining final hip/knee extension and neutral pelvic tilt. You can really feel them pull at the anterior distal pelvis if you do this. A good demonstration is doing a standing pelvic tilt with a lot of thrust, locking the glutes. Here is where "pulling the pelvis to the rib cage" by the insertion point causing rotation is important. Paul Chek and others have sited research saying that the abdominals contract as a unit with equal stimulation occurring throughout the muscle. But from my experience the best assistance exercise that makes me tight below the belt and seems to help my squat is reverse crunches done on a steep incline board for 4 sets of 12-15 reps. I completely agree with you that just doing squats will give you stonger abs. Im going to up check on some studies about this if I ever get a chance. Does anybody have any research?