Interesting critical analysis of McKenzie theories. I too share your skepticism
of the theories. I do use modified "McKenzie" interventions with great success.
While it has been a while since I have reviewed McKenzie's book, I seem to
remember he does not address the facet joint. It is the restoration of normal
facet and hence segmental mobility that I believe is the basis for most of the
success with "McKenzie" not a mechanical effect on the disc for the very reasons
you observed.

Douglas M. White, PT, OCS
Milton, MA USA


[log in to unmask] wrote:

> This commentary on McKenzie exercises which I submitted to another user group
> may also be of interest here in stimulating some further discussion on back
> care.
>
> Member A wrote:
>
> <<The McKenzie Exercises are actually a series of stretches, either backward
> or forward. They work by stretching the spine  and this, in turn,  increases
> the intervertebral space. . . .
>
> <<When the pressure on the spine is relieved, the fluid flows back into the
> center
> for the disc, essentially re-inflating it.  Daily changes in the amount of
> fluid retained and expelled from intervertebral discs account for daily
> variations in body height of as much as 2 centimeters.>>
>
> ***This implies that a significant flow of cerebrospinal (CS) fluid takes
> place through the poroelastic annulus fibrosus during the few minutes of a
> typical Mc Kenzie procedure.   This suggests a fairly rapid flow rate through
> this thick ring.  Yet, research indicates that this type of flow requires
> several hours, as is corroborated by the remark that there are daily
> variations in body height of as much as 2cm.  Is there now new research which
> shows definitively that stretching manoeuvres such as the McKenzie exercises
> produce a much higher flow rate?
>
> Now, this height variation of some 2cm takes place over a period of at least
> 8 hours and is most marked during the period of sleep when no forced active
> or passive stretching of the spine takes place!  If increase in the volume of
> the nucleus pulposus is indeed the primary cause of reduced low back pain,
> then inactive bed rest or sleep logically would appear to be more effective
> than McKenzie methods, since the reflux of CS fluid occur quite naturally and
> to a greater extent during unstretched bed rest.
>
> Another issue - McKenzie most frequently involves controlled prone lumbar
> hyperextension and presumably stretches the anterior aspect of the fibrous
> annulus. This frequently reduces LBP, depending on the individual case, but
> if one performs marked forward flexion (as is also sometimes used with
> McKenzie), which presumably also stretches the posterior portion of the
> fibrous annulus, this action can further traumatise the lumbar spinal
> structures.  Yet, this opposite stretching action would, according to the
> above theory, also cause reflux of CS fluid into the nucleus of the disc.  In
> other words, there appear to be several contradictions in this CS reflux
> hypothesis.
>
> Fortunately, McKenzie suggests that reduction or exacerbation of LBP by each
> bending manoeuvre tells us which action is most appropriate for a given
> patient.  However, there is no certainty at all that any change is due
> predominantly to increase in volume of the nucleus of the lumbar discs.
>
> There are several other biomechanical issues involved:
>
> 1. Basic physics tells us that the fluid pressure is the same everywhere
> inside the nucleus, irrespective of where any stretching of the anulus
> occurs.  In other words, if one stretches the annulus anywhere, anyhow, an
> equal drop in pressure will occur throughout the nucleus - whether one bends
> the spine forwards, backwards, sideways or longitudinally (by traction).  Of
> course, we do know that some of these actions can severely exacerbate LBP.
>
> 2.  Besides stretching one aspect of the lumbar discs (and compressing the
> opposite side!), lumbar extension implicates stretching of other structures
> including the abdominal musculature and connective tissue, the hip flexors,
> and the anterior longitudinal ligament of the spine. It is also possible that
> some stretching of the lower spinal nerves also takes place.  How can we
> state categorically that the stretching of the discs is the most important
> issue involved?'
>
> 3.  As noted in 2 above, if lumbar hyperextension causes stretching of the
> anterior aspect of the lumbar discs, then it simultaneously causes
> compression of the posterior aspect of the same discs.  Since McKenzie
> sometimes may involve lumbar flexion exercises, then it presumably implicates
> both types of stretch and leads to some sort of hypothetical balance.
>
> 4.  Sometimes stretching of the spinal structures produces sudden (phasic) or
> gradual onset (tonic) protective spasm, so that avoidance of any form of
> stretching (as imposed by McKenzie or slumped sitting) would appear to be the
> wisest option in such cases.
>
> <<As daily stresses and pressure on the spine (e.g., from activity and
> sitting) compress the intervertebral space, dics fluid flows out into the
> surrounding tissue.   As this happens, dics flatten out and some eventually
> begin to impinge on nerves which branch out from the spinal cord.   The
> result is pain, discomfort and decreased mobility.>>
>
> ***Even this theory is rather tenuous, since there is not a greater incidence
> of LBP among long-term Olympic weightlifters, whose type of training imposes
> extremely large compressive loads on the lumbar spinal discs.  In fact, quite
> the opposite is noted among competitive lifters.  Research suggests that
> sustained low intensity loading of articular joints, rather than regular
> impulsive loading is associated with a greater incidence of articular
> degeneration, so that it is not simply a matter of daily stress which leads
> to spinal deterioration, but the type and pattern of loading involved.
> Regular periodic loading of the spine would seem to cause adaptation which
> then minimises the occurrence of spinal and other joint deterioration.
>
> Interestingly, some of the Olympic lifting exercises such as snatches,
> overhead pressing and pulls from the ground involve a type of active
> extension of the lumbar spine, thereby invoking a special variation of what
> loosely may be called a McKenzie manoeuvre.  Yet, the medical and fitness
> professions generally are opposed to this type of physical loading.
>
> <<The designer of the BackTracker device calls it a personal traction device,
> but it is primarily a stretching machine with natural traction.  I use the
> word "machine" lightly, however:  it is not electrical, but more like a small
> home exercise unit.>>
>
> ***When I was on a research visit to Russia I was given extracts from a book
> written over 20 years ago on back care and training, which even claimed to
> increase the height of children.  In it were designs for progressively loaded
> personal natural traction devices (using weights inter alia) to be used even
> while one was sleeping. It claimed great success in reducing LBP and
> increasing height of children, but especially if used as part of a special
> intensive weightlifting regime. The use of passive stretching alone was not
> encouraged, because this apparently does not enhance the ability of the body
> to adapt to the compressive loads encountered in daily life.
>
> There were also Russian designs for devices which imposed ballistic
> longitudinal loading of the body and this produced very significant increases
> in spinal integrity and jumping strength and power, as has been corroborated
> by Italian scientists more recently (I believe that they have patented and
> produced a ballistic loading device based on their work).
>
> Please note that none of this commentary is intended to denigrate McKenzie
> exercises (which, after all, are just a modern adaptation of therapeutic
> yogic and Taoist postures used thousands of years ago in India and China) -
> it simply questions if current theories underlying its successful
> applications are scientifically acceptable.
>
> Dr Mel C Siff
> Denver, USA
> [log in to unmask]




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