An interseting article.


The Core Stability Cult


Mel C Siff PhD

Attend any fitness conference, read any fitness magazine and invariably you
will come across some 'exciting' revelations on 'core stability', 'core
strength' or 'balance training'. These related topics have become so
lucratively popular that they have attained the status of a cult, one which
suggests that almost all of us have some sort of functional deficit in our
'trunk stabilisers', transversus abdominis, spinal postural mechanisms,
pelvic orientation or rectus abdominis. As such, it is likely that we are
doomed to a life of regular back pain and disability, attended by a host of
other posture related disorders, or at least, so we are told.

The solution? We are told to try one of the following - do special
exercises on balancing balls, make deliberate attempts to awaken our
transversus abdominis muscles from the dead, realign the pelvis, stretch some
offending stiff soft tissues, discard any belts that you may use when lifting
weights or refuse to hold your breath while training.

Do these methods work? Are they the best way of improving core function?
Yes, they do work in some cases, but the basis on which they operate
invariably is not as explained by their promoters, nor are they any more
effective or efficient than any other methods of improving postural control.
The fact that these stabilising exercises are based upon largely on the
“isolation principleâ€* of concentrating attention on individual muscles
means
that they are usually less efficient time wise than other stabilising methods
which develop stability alongside muscle strength, size, flexibility and
endurance.

At the very outset, we have to dispel the belief that it is possible to focus
on 'core stability' on its own. Unless one's entire body is off the ground
or is immersed in water, the idea of stabilising the core separate from other
parts of the body is sheer nonsense, since the ability of the core in all
sports in which one is in touch with a static or moving surface depends
strongly on peripheral stability. If one is carrying out some movement such
as lifting weights, doing aerobics, running, jumping or playing some
ground-based sport, the body stabilises as a whole, with interacting
contributions from the periphery and the core.

It is simplistic and misleading to identify the core of the body as being the
central component of human movement, like some sort of superior machine which
links and controls the relatively less important extremities of the body.
Problems anywhere in the body's musculoskeletal system may lead to injuries
or dysfunction. Research has not even shown that non-traumatic
dysfunctions or that “muscle imbalancesâ€* of the core muscles directly cause
back problems.

To be more accurate, core stabilisation, according to most of the textbooks
and therapists who address this issue, really refers to entire body
stabilisation. However, I have not yet seen any study which has assessed
so-called "core stability" without peripheral stabilisation concurrently
being involved in the whole stabilisation process. Until this sort of "free
space" testing being done, the nature of core stability must remain highly
speculative, as is already emphasized by the considerable amount of
disagreement regarding trunk stabilisation and motor control in the
biomechanics community.

Optimal core stabilisation is not even a static process, but a dynamic state
which changes with every slight change in body disposition in space and time.
Research by Verkhoshansky and others has shown that, even though a given
motor pattern may be repeated in almost identical fashion, the underlying
joint and muscle recruitment patterns may be significantly different every
time. Brain scans taken during human movement have shown that the same
regions of the brain are not necessarily involved in controlling the
identical movement. There is no such thing as one fixed optimal inner state
for the joints, nervous excitation patterns and soft tissues involved during
any movement, even though the external movement pattern remains virtually the
same for many repetitions.

The concept of core stabilisation is not synonymous with core strengthening,
and isolated core strengthening, in the absence of appropriate motor skills
training, does not necessarily enhance core stability or postural management.

Nobody has yet established during any specific dynamic sporting act exactly
what percentage of the action is managed by core strength and how much by
peripheral strength, if such a separation between functions is indeed
possible. Even if this one day becomes possible, the relative strength
ratios for muscles in any joint action change from point to point, so that
static strength tests will tell us nothing about dynamic muscle ratios in
complex sporting movements.

The balance ball and wobble board probably are the most popular methods for
training stability of the body, but these methods, though helpful in early
rehabilitation, have never been shown to enhance stability in dynamic sport.
Physics tells us that the centre of mass (COM) of the body must be positioned
over the base of support (BOS) established by the feet in order to maintain
static equilibrium during upright stance.

Ball and board training focuses on control of the COM over a fixed BOS, but
it is important to appreciate that it is the relationship between COM and BOS
that defines COM stability. In fact, if the body experiences postural
perturbation, alteration of the BOS, through stepping or other movements of
the limbs makes much greater contribution to the control of COM stability
than control of the COM itself. It has also been found by researchers such
as Toussaint that foot placement control under dynamic conditions appears to
be the more important factor affecting stability during running and any
sports involving movement of the feet.

Balls and boards may impart patterns of stabilisation which can differ
significantly from those used in sport. This has been shown in a study in
which subjects had to abduct one leg while standing. Different strategies
were used to maintain the COM over the BOS during this action, with trained
dancers counter-rotating the hip and ankle to maintain a near-vertical trunk
orientation, unlike non-dance trained individuals who inclined their trunks.

Other research has shown that postural strategies involving very different
patterns of ankle and hip motion may control sagittal plane COM motion
initiated by external disturbance of static stance. In situations that
prevent effective use of the "ankle strategy", subjects can learn to execute
a "hip strategy" which sacrifices control of vertical trunk orientation to
achieve COM stability. However, the natural stabilising tendency to is to
move the feet in a stepping reaction, so that any form of balance training
must address this issue. Control of COM alone is insufficient to ensure
stability; the central nervous system must also control the BOS. Moreover,
the stability limits during movement depend on the velocity of motion of the
COM, as well as the displacement of the COM and BOS relative to one another.

It also appears that two concurrent and coordinated controllers exist for
stabilising the body: one for posture and the other for movement. Ball
training does not adequately train these two balance control subsystems.

It is also invalid to any analyse or prescribe balancing exercises on the
basis of models relying primarily on 'core stabilisation' and trunk control,
since the latter, unlike the ankle, is more unstable in pitch and roll
planes. Moreover, it is misleading to devise balancing and core control
methods based upon research using injured, diseased or senile subjects,
because the strategies involved in each case can be very different and
inapplicable to one another. In order to make such extrapolations from
clinical models, it is essential that the biomechanical consequences of a
disease state and muscle responses underlying instability of the trunk be
understood. Research by Allum has also shown that one must distinguish
between balancing problems and strategies involving central and peripheral or
proprioceptive processes in the limbs, something that crude balancing methods
on physio balls or wobble boards do not adequately address.

Stabilisation has to take place under slow and very rapid conditions, the
latter being of great importance because all dynamic sports and falling
accidents among older adults happen under explosive or ballistic
circumstances. Balancing involves both anticipatory and reactive control
through feedforward (mentally preprogrammed processes established in advance
of the action) and through ongoing feedback from the proprioceptive and
vestibular systems. Now, balance relies heavily on the perception of self
location and motion in space. This perception involves vestibular input when
the support is perceived as moving , but it is based primarily on
proprioceptive input when the support is stationary. Clearly, stability
training on a ball is very different from stability training in actual sport.

Belenkii and coworkers investigating voluntary arm movements, were the first
to demonstrate the presence of feedforward muscle activation and anticipatory
postural adjustments. Current models of voluntary movements and posture
incorporate both feedforward and feedback control mechanisms closely
integrated with adaptive gate and gain control (cybernetic) processes taking
place in the nervous system. Interestingly, these recent studies of postural
control mechanisms during quiet upright standing support the idea that
continuously available sensory information, although detected, is not always
utilised for closed-loop control unless a certain sensory threshold is
reached.

Consequently, it may be argued that the need for coordination for successful
restabilisation is task and context specific and that each individual has a
maximal restabilisation ability which is limited by their coordination skill.
In fact, Oddsson recently found that the 'śstepping threshold', i.e., the
level of perturbation an individual can sustain without stepping, varies
almost three-fold within a group of healthy young subjects.

This implies that certain individuals may be more prone to lose balance and
thus incur fall related injuries. Such information may have far reaching
implications for our current view of injury prevention in sport and the
workplace. However, it has also been noticed that subjects with a
background in sports commonly have higher stepping threshold, thereby
suggesting that this skill can be influenced by the varieties of skilled
motor activities involved in sports training.

It is important to note that a successful restabilisation process not only
requires coordination but also fast and powerful actions. In fact, it has
been proposed that quick postural corrections may be associated with an
altered activation order in which fast motor units are activated early or
even before slow ones. This makes intuitive sense with respect to the demands
of the situation. The quicker a corrective step can be initiated and
executed, the sooner balance will be regained and the effect of the
perturbation will be minimised. In fact, the ability to quickly jump, shift
the whole body or execute a few sprint-like steps could very well be the most
important survival strategy required for balance recovery from a fall event
that otherwise could have caused serious injury or death. However, current
rehabilitation programs rarely incorporate exercises that improve explosive
power, which suggests an important area for future research. In fact, this
type of strategy is actively discouraged by most therapists and trainers.

Postural perturbations occurring during different ongoing voluntary movements
have rarely been studied. Scientists have recently investigated postural
perturbations during lifting and found that certain situations may trigger
conflicting or rapid switching between motor commands, presumably the
reactive postural response and the ongoing voluntary one.

The world of core stabilisation currently remains far too heavily based in
marketing and belief than in valid science. Are the current models of core
stabilisation and postural training placing too great an emphasis on isolated
processes at a stage when the therapeutic world is now taking far more notice
of more integrative processes than ever before?

What is one to do? Well, firstly, since research to date has not yet shown
that the cost, time and effort spent on trendy ball and board training offers
anything superior to many other existing methods of core stability and
balance training, you can quite happily dispense with balancing balls and
boards. What should you do instead? The exceptional balancing and
stabilisation skills acquired by gymnasts, circus performers, divers,
trampolinists, martial artists, skaters and many other athletes shows us that
we can simply take natural sporting manoeuvres and exercises and adapt or use
them unchanged to enhance whatever balancing and coordination skills that you
may need. If you are a competitive athlete, then you can very successfully
use variants of your specific sporting skills under slightly more unstable or
more demanding conditions to improve your performance. For those who may be
interested in these types of training strategy, I discuss the use of
intentionally destabilised snatches by Russian Olympic weightlifters and
various gymnastic techniques in my book "Supertrainiing" (Siff MC, 2000).
Such methods have produced the world's most successful and most impressively
coordinated athletes without any use of a myriad of telemarketed core
stabilisation and ball balancing tricks. Clearly, the highest levels of
sporting practice corroborate the findings of science. Why not use them -
free? After all, they are right there, waiting for you in your favourite
sports or recreational activities!

Dr Mel Siff

Thanks Cool Hand Luke, that was an interesting article.

Tim, Your welcome.Another opinion.Thoughts?


" Yes, I've well aware of the 'improper TVA recruitment' theory and I'm pretty sure it will bite the dust-if,and when the dust ever settles that is.I am not convinced that the nervous system 'forgets how'to stabilize thespine,nor am I convinced that the TVA is as important to spinal stabilization as Chek and others make it out to be.Whenever this subject comes up,I tend to smell a lot of 'fitness industry hype.Who knows,maybe in a few years I will be proven wrong, but I've seen way too many inconsistencies regarding all the fascination with the TVA and spinal stabilization.

What's wrong with trying to regain 'optimal spinal stabilization recruitment patterns'simply by using a very gradual progression (starting at a very low level) of full body movements(i.e. sqauts,deadlifts,cleans,jerks medicine ball throws)that require varying levels of trunk stability?To tell someone they need to consciously suck their naval to their spine prior
to performing any exercise is like instructing someone that they need to focus on contracting their quadriceps every time they take a step.We all learned to stabilize our spines when we were a baby and we never forgot."

Eric Burkhardt
Strength and Conditioning Coach
UC Irvine

More Stuff;

" Since the topic of postural correction and muscle imbalance has once again reared its distorted head,it becomes appropriate to expand upon an earlier version of one of my previous articles on the work of Janda.

If one examines the work of the Czech medical practitioner, Vladimir Janda,it soon becomes apparent how many therapeutic and fitness gurus, including large numbers of chiropractors and Paul Chek,have adopted him as one of their major gurus, despite the lack of scientific and clinical substantiation of all of his theories, claims and methods.Even if such methods one day happen to find some genuine validation in the realm of pathology, this will not necessarily prove that the same methods can be applied effectively to the world of healthy sport.

Let us begin by reading an extract written on the ChiroWeb site to set the stage for our analysis:

http://www.chiroweb.com

Janda proposes propriosensory treatments such as balance training as the mainstay of subcortical training.Sensory motor stimulation from the soles of the feet (rocker/wobble boards or balance shoes) or pelvis (gymnastic balls) can increase the speed of activation of inhibited muscles and decrease the irritability threshold of hypertonic muscles on a subcortical or semi-automatic basis.

References:

1. Janda V & Vavrova M. Propriosensory training. In "Rehabilitation of the Spine: A Practitioner's Manual" , Liebenson C (ed). Williams and Wilkins, Baltimore, 1995.

2. Bullock-Saxton JE, Janda V, Bullock MI. Reflex activation of gluteal muscles in walking. Spine 18:6; 704-708, 1993. >

** Note Janda's belief that balls and wobble boards are effective rehabilitation tools in the pathological sense. Note that he nowhere suggests in the above references that these same methods may be extrapolated with equal success to the world of sport.

Let's go further by reading what Joseph A. Cimino, D.C. has to say about Janda:

http://www.chiroweb.com/archives/



The following more critical commentary on Janda's work makes for some interesting and sober reading:

THE CASE OF JANDA

American Back Society Meets in Las Vegas

Robert Cooperstein,DC



---------------------

Dr. Janda has for many years asserted that much musculoskeletal pain arises at least partly from a chronic shortening of certain muscles which cause alterations in normal muscle activation patterns. The muscles allegedly most prone to this shortening are:

Rectus femoris Hamstrings Iliopsoas Tensor fasciae latae Gastrocnemius-soleus Tibialis posterior Short hip adductors Sartorius

Piriformis Lumbar Erector Spinae Quadratus Lumborum

Pectoralis Major Upper Trapezius Flexors of upper limb

Levator scapula Scalenes Sternocleidomastoid

The effectiveness of Janda's treatment approach have not yet been definitively proved by any scientists, as was noted in the artciel immediately preceding this one, even though it has become accepted by many members of the chiropractic and other therapeutic professions.

The Janda approach for dealing with dysfunction and posture is based upon the functional pathology of the motor system model ("DC" June 16, 1995). According to Janda, dysfunctional patients typically do have "adaptive shortening" as suggested by the physiotherapist McKenzie, but such shortening is usually not the cause of their pain - instead it is an adaptation to injury, poor posture, or repetitive strain.

Another chiropractor, Stephen Perle, wrote on the BIOMCH-L list (Oct 2000):



This is how Warren Hammer, D.C summarises some of Janda's work:

http://www.chiroweb.com/archives/

Muscle Tightness



***Note that the above is all speculative and has not been proved scientifically or medically. First of all, an emphasis on muscle "weakness" does not emphasize that muscle strength is not a local or isolated muscle property, but a consequence of the degree of neural excitation of that muscle at any given time. Thus, "weakness" may simply be a consequence of lack of training or motor skill. Then, in referring to "tight" muscles, how does Janda distinguish between mechanical tightness or diminished extensibility of the muscle complex and neuromuscular limitations of muscle function?

-----------------------------

*** The following commercial website sells some of fairly costly Janda books and videos and provide photographs of balancing methods that show clearly how inspirational his work has been to the latter day promoters of balance balls, wobble boards and so on:

http://www.OPTP.com/shop.cfm?groupid=Balance%2F%20Proprioception%20Training&catid=Resources#JC1

Well, let us hope that the above brief overview of the Janda model and approach to rehabilitation will prove enlightening to those who may not have come across his work and the enormous impact he has had on various gurus who liberally and often unquestioningly apply and extrapolate his work on clinical pathology to the conditioning of healthy athletes. As usual, any comments are welcomed.

For those who wish to read more about Janda's work, here are a few references:

JANDA REFERENCES

Hammer WI, ed. Functional Soft Tissue Examination and Treatment by Manual Methods: The Extremities. 2nd ed. Gaithersburg, MD: Aspen Publishers, Inc,,
1999. (Hammer WI, ed.)

Janda V Evaluation of Muscular Imbalance. In Rehabilitation of the Spine: A Practitioner's Manual, Liebenson C (ed). Williams and Wilkins, Baltimore,
1995.

Janda V. Muscles as a pathogenic factor in back pain. IFOMT Conference. Christchurch, New Zealand, 1980:1-20.

Janda V. The relationship of hip joint musculature to the pathogenesis of low back pain. International Conference on Manipulative Therapy. Perth, Western Australia, 1983:28-31.

Janda V. Rational Therapeutic approach of chronic back pain syndromes. Symposium chronic back pain, rehabilitation and self help. Turku, Finland,
1985:69-74.

Janda V. Pain in the locomotor system - A broad approach. In: Glasgow EF, Twomey LT, Scull ER, Kleynhans AM, Idczak RM, eds. Aspects of Manipulative Therapy. 2nd ed. New York: Churchill Livingstone, 1985:148-51.

Janda V. Muscle weakness and inhibition (pseudoparesis) in back pain syndromes. In: Grieve GP, ed. Modern Manual Therapy of the Vertebral Column. New York: Churchill Livingstone, 1986:197-201.

Jull GA & Janda V. Muscles and motor control in low back pain: Assessment and management. In: Twomey LT, Taylor JR, eds. Physical therapy of the low back. New York: Churchill Livingstone, 1987:253-78.

Janda V: Muscles and cervicogenic pain syndrome. In Grant R: Physical Therapy of the Cervical and Thoracic Spine. Churchill Livingstone, New York, 1988.

Liebenson C, ed. Rehabilitation of the spine: A Practitioner's Manual. Baltimore: Williams & Wilkins, 1996.

Dr Mel C Siff Denver,