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THE INNER UNIT

A NEW FRONTIER IN ABDOMINAL TRAINING

BY: PAUL CHEK

FROM: IAAF TECHNICAL QUARTERLY: NEW STUDIES IN ATHLETICS 4/99

 

Paul Chek is an expert in the fields of corrective exercise and high performance conditioning and is the founder of the C.H.E.K lnstitute in San Diego, California.
For over fiftees years he has traveled around the world lecturing, consulting, and giving seminars. Paul Chek has been a consultant to the Los Angeles Chiropractic College, the Chicago Bulls, the Denver Nuggets, the US Army Boxing team, Australia's Canberra Raiders and the US Air Force Academy.

The author states that abdominal exercises can be performed in various ways and asks if the exercises commonly practiced really improve the functionality of the abdominal muscles.

From his own studies with patients and clients who performed a high volume of abdominal routines, he concludes that the usual theories of explanation and treatment for back pain are wrong. He recommends the concept of "The Inner Unit", which is a term describing the functional synergy between specific abdominal muscle groups. He describes ideas for Inner Unit conditioning and concludes that Inner Unit training provides the essential joint stiffness and stability needed to give the large prime movers of the body a working foundation.

 

    How many ways can you do an abdominal exercise? Well, if you have been reading the muscle tabloids for the past 20 years you could probably come up with well over 100. Today we have classes devoted to nothing but TRASHING people's abdominal muscles, complete with every variation of crunch, jack knife, side bend and leg raise exercise known to man. Are these classes, or these exercises, really improving the way you look or function, or reducing your chances of back pain?
    To find the answers to these questions, in 1992 I began investigating the correlation between abdominal exercises performed, exercise volume and the postural alignment, pain complaints and overall appearance of my clients. To ensure objective observations of postural alignment and responses to specific exercises, I designed and patented calibrated instruments to measure structural misalignment.

    In the first year of recording such information as forward head posture, rib cage posture, pelvic tilt and overall postural alignment, it became evident that those performing high volume sit-up/crunch exercise programmes were not showing promising results (see Figure 1)! Those attending "Ab Blast" classes and/or performing high repetition/high volume abdominal routines were not only having a harder time recovering from back pain, they were also showing little or no improvement in their postural alignment.
    While studying patients and clients who performed high volume abdominal routines, it became very evident that there was a common link. About 98% of those with back pain had weak lower abdominal and transversus abdominis muscles. While those with no history of back pain were frequently able to activate the transversus abdominis and scored better on lower abdominal strength and coordination tests. To alleviate back pain, I frequently had to suggest that clients stay completely away from any form of sit-up or crunch type exercises. When this advice was adhered to, and exercises for the lower abdominal and transversus abdominis were practiced regularly, back pain either decreased or was completely alleviated and posture routinely improved.
    One can always find some "experts" in the health and fitness industries who state that "there is no such thing as lower abdominal muscles," while others suggest that the best treatment for back pain is to exercise on machines that isolate the lower back muscles. My clinical observations lead me to believe both theories are wrong.
    In 1987, "Clinical Anatomy of the Lumbar Spine" by Nikolai Bogduk and Lance Twomey was published (1). This book is important because it was Bogduk who made the first clinical observations of how the abdominal and back muscles worked together as a function unit. This occurs via the connection of the transversus abdominis and internal oblique muscles to the envelope of connective tissue (thoraco-lumbar fascia) surrounding the back muscles (Figure 2).
  A few years ago, Australian researchers Richardson, Jull, Hodges and Hides began making significant headway in understanding how the deep abdominal wall worked in concert with other muscles, creating what they would later call THE INNER UNIT (2) .

 


 

FIGURE 1

    Those regularly performing crunch and sit- up type exercises frequently demonstrate forward head posture (A); note that when head carriage is normal the dotted line through the cheekbone should fall in the same vertical plane as the sternum and pubic symphysis. (8) When the rectus abdominus becomes chronically shortened. it pulls the chest downward, increasing first rib angle; this is commonly associated with shoulder dysfunction and impingement of the nerves feeding the arm as they exit the cervical spine. (C)
    When the hip flexors strengthen and shorten from chronic exposure to the sit- ups, leg extension and leg lowering
exercises commonly used in abdominal workouts, the lower abdominal and hamstring muscles are lengthened, frequently demonstrating positional weakness.
    The postural changes demonstrated here are common among today's athletes and can be corrected through improved control and strengthening of the inner unit musculature.


 

FIGURE 2

The thoracolumbar fascia system envelops the inner unit musculature to create the body's own natural weight belt. Activation of the transversus abdominis aids in stabilization of the lumbar spine. When wearing a weight belt, the natural tendency is to push outward against the belt, which inhibits the transversus abdominis and may lead to faulty motor programming and destabilization of the spine!


 

FIGURE 3

The inner unit is under separate neurological control from the larger outer rectus abdominis, external oblique and anterior fibers of the obliquus internus. Traditional gym exercises do not condition these key muscles in such a way that their ability to improve spinal stability is enhanced until their recruitment is under automatic reflex control. To accomplish automatic reflex control of the inner unit requires specific isolation training to enhance sensory- motor control. Once control is established, activation of the inner unit must be programmed into all movement patterns commonly used by the individual. Failure to condition the inner unit to a high level of specificity often results in spinal injury due to instability.



The Inner Unit


    The Inner Unit became accepted as a term describing the functional synergy between the transversus abdominis and posterior fibers of the obliquus internus abdominis, pelvic floor muscles, multifidus and lumbar portions of the longisssimus and iliocostalis, as well as the diaphragm (Figure 3). Research showed that the inner unit was under separate neurological control from the other muscles of the core (2, pg. 49). This explained why exercises targeting muscles such as the rectus abdominis, obliquus externus abdominis and psoas, (the same muscles exercised in traditional abdominal conditioning programmes common allover the world) were very ineffective at stabilizing the spine and reducing chronic back pain.
    Exercising the big muscles (prime movers) was not providing the correct strengthening for such essential small muscles as the multifidus, transversus abdominis and pelvic floor muscles. When working properly, these muscles provide the necessary increases in joint stiffness and stability to the spine, pelvis and rib cage to provide a stable platform for the big muscles. In a sense, as the big muscles (outer unit) become stronger and tighter, the delicate balance between the inner and outer units becomes disrupted. This concept is easier to understand using the pirate ship model (Figure 4).


FIGURE 4

Although the large guy wires (outer unit) support the mast of the pirate ship, its functionality is completely dependant upon the support provided by the small guy wires which represent the muftifidus and inner unit muscles in this analogy.



    The mast of the pirate ship is made of vertebra which are held together (stiffened) by the small guy wires running from vertebra to vertebra, just like the role of the multifidus (a member of the inner unit) in the human spinal column.
    Although the big guy wires (representing the outer unit) are essential to hold up the mast of the pirate ship (our spine), they could never perform this function effectively if the small segmental stabilizers (inner unit) were to fail. By viewing the pirate ship's large guy wires, it becomes easy to see how developing too much tension from the overuse of exercises such as the crunch, could disrupt the posture of the mast, or spinal column in the case of a human.
  To better apply the concept of the pirate ship, let's examine how the inner and outer units work in a common situation such as picking dumbbells up from the floor in the gym (Figure 5). Almost in synchrony with the thought, "Pick up the weights from the floor," the brain activates the inner unit. contracting the multifidus and drawing in the transversus abdominis. This tightens the thoraco-lumbar fascia in a weight belt-like fashion (Figure 2). Just as this is happening, there is simultaneous activation of the diaphragm above and the pelvic floor below. The effect is to encapsulate the internal organs as they are compressed by the transversus abdominis. This process creates both stiffness of the trunk and stabilizes the joints of the pelvis, spine and rib cage, allowing effective force transfer from the leg musculature, trunk and large prime movers of the back and arms to the dumbbells.


FIGURE 5

Such functional tasks as picking up dumb bells off the gym floor require synergistic function of the inner and outer units. Failure of the inner unit for any reason, pre- disposes the spine to forces that frequently cannot be effectively stabilized and dissipated, resulting in spinal injury and or sacroiliac joint injury


     When the inner unit is functioning correctly, joint injury is infrequent, even under extreme loads such as pushing a car, tackling an opponent in football or lifting large weights in the gym. When it is not functioning correctly, activation of the large prime movers will be no different than a large wind hitting the sail of the pirate ship in the presence of loose guy wires running from vertebra to vertebra in the mast. Any system is only as strong as its weakest link!

 


Inner Unit Conditioning Tips


   
The first and most important step towards reducing back pain, improving posture and the general visual appearance, is to stop all crunch and/or sit-up type exercises until you become proficient at activating your inner unit! Although the assessment procedures for the inner unit are beyond the scope of this article, the interested reader may find detailed information in the video series "Scientific Core Conditioning" (3). With inner unit dysfunction being extremely common in today's working and exercising population, it is safe to assume that everyone needs to start with novice exercises, even the most elite of athletes.
    To begin conditioning the transversus abdominis, use the 4 Point Transversus Abdominis Trainer (4) (Figure 6). For conditioning of the multifidus and related stabilizer and postural muscles, the Horse Stance exercises may be used (4,5,) (Figures 7-9).
    Although the exercises may seem simple from looking at the diagrams here, they are actually very technical and must be executed with exact precision (see Scientific Back Training (5) or The Golf Biomechanic's Manual (4) for more details). These exercises are only a small sample of the number of inner unit exercises available (4,5), but, when done correctly, they are sufficient to make a noticeable difference in the way your body functions.
    To get the most from the inner unit exercises shown here it is suggested that the exercises be done 3-4 times per week as an individual workout. To get the best results from these exercises while continuing with a traditional gym program, I suggest you stop all crunch and sit-up exercises and replace them with the exercises demonstrated here.
    Always perform an inner unit exercise as the last exercise of your training session, i.e. perform one exercise after each workout. Alternate through the exercises, selecting either the 4 Point Transversus Abdominis Trainer or a variation of the Horse Stance exercises after each training session.
    It is very important not to fatigue the stabilizer system before attempting traditional free weight exercises or injury is likely! In implementing the stabilizer exercises into a machine-based program, you should intersperse the exercise amongst the machine exercises.
    The inherent stability provided by machines makes it unlikely that you will become injured. As your stabilizer system improves, I suggest progressively replacing machine exercises with free weight exercises, as machine-based programmes do nothing to enhance functional strength and stability.
   Should you begin adding free weight exercises to a machine-based program, you must always perform your stabilizer training after completion of all free weight exercises. In a future article I will discuss such key concepts of Outer Unit training as:

 

 

 


FIGURE 6 (FOUR POINT TRANSVERSE ABDOMINUS TRAINER)

Assume this position as the start position.


FIGURE 7 (HORSE STANCE VERTICAL)

 


                            FIGURE 8A                            FIGURE 8B                                            FIGURE 9

                        

 


It is critical that you only perform as many repetitions as possible with perfect form! Failure to follow these instructions will result in futile attempts at conditioning and no improvement. Lack of attention to detail is exactly why many exercise programmes fail!

 

  1. The head and neck should stay in line with the spine. The head should not be dropped or lifted at any time.

  2. The elbow of the support arm should point directly backwards. not to the side.

  3. The arm that is up should maintain an angle of 45 off the midline of the body at all times.

  4. The shoulders and hips should remain parallel with the floor at all times.

  5. There should be no significant movement of the lower back. The movement of the leg needed to draw the letters of the alphabet should come from the hip.

  6. The lower leg should move as a unit with the thigh. It is not good technique just to use the lower part of the leg.

  7. Draw the navel towards the spine throughout. but do not disrupt respiration by over-recruiting the trans- versus abdominis.

  8. Perform as many repetitions as possible with perfect form before switching sides. This is indicated in your Reps column as Max. When you can perform the alphabet on either side with perfect form, add a 1 Ib. wt to each wrist and a 3 Ib. weight to each ankle.


Conclusion


    Inner unit training provides essential joint stiffness and the stability needed to provide the large prime movers of the body with a working foundation.
    When outer unit or prime mover exercises are executed in the absence of a functional inner unit, poor posture, unwanted visual changes and musculoskeletal injury are inevitable.
    For optimal health and performance, the inner unit must not only be functional, but must be maintained with technically correct exercise protocol.

References
1. BOGDUK, N. Et TOWMEY, L. (1987)
Clinical Anatomy of the Lumbar Spine. Churchill Livingstone.
2. RICHARDSON, C., JULL, G., HODGES, P. HIDES, J. (1999)
Therapeutic Exercise. For Spinal Stabilisation in Low Back Pain. Churchill Livingstone.
3. CHEK, P. (1999)
Scientific Core Conditioning Video Correspondence Course. Encinitas: C.H.E.K Institute.
4. CHEK, P. (1999)
The Golf Biomechanic's Manual -Whole In One Golf Conditioning. Encinitas: C.H.E.K Institute.
5. CHEK, P. (1994)
Scientific Back Training Video Correspondence Course. Encinitas: C.H.E.K Institute. .


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