In response to Dr Mel Siff’s Subluxation Paradox http://www.melsiff.com/12359/subluxation-puzzle-and-paradoxes-by-mel-siff/
Here is some further discussion from another list on my subluxation paradox:
Mel Siff:
< Can you cite any scientific references which definitely relate these small
“disturbances” to any significant pathology? What you are iimplying is that
the spine is critically tuned, displays a very sharply defined range of
efficient functioning and has a negligible “safety factor”, so that even
minor perturbations will cause genuine pathology or pain. This is not a very
efficient way for the body to have developed and evolved, so I have to wonder
about the validity of such an hypothesis.>
Comment:
Your point about the evolution of the system is well taken. As you point out
there must be some safety factor. I am not trying to suggest that it is
negligible, merely susceptible to problems. For example when trunk
stabilization via muscles is especially important in neutral spine postures
due to the inherent low levels of stiffness in the “neutral zone” (a small
range about the mid-position of the joint where little resistance is offered
by passive constraints).
The multifidus has been implicated in providing much of the control in the
neutral zone. Several other mechanisms contribute to trunk stability
including muscle stiffness, co-contraction, and pre-programmed (i.e.
anticipatory contractions) contractions.
Perturbal first maintain posture (primary task) and second, perform voluntary
tasks (secondary task) when the two are presented concurrently. This makes
sense in that without adequate posture, voluntary movements do not happen.
However, the co-demand of voluntary movement and postural control can lead to
a sudden loss of balance, particularly when performing rapidly or under high
loads. Such events have been called “motor errors”. These “errors” can lead
to injury through inappropriate coordination dynamics that require different
functions out of the same muscle(s). An acute injury (eg whiplash) can
instantly impair stabilization due to tissue damage which leads to
subluxation. However, more frequently, authors view repeated motor errors
over the long term as the primary in subluxation. This last statement has
yet to be verified.
Here are a few references:
1. Burns LA. Viscero-somatic and somato-visceral spinal reflexes. J Am
Osteopath Assoc 1907; 7:51.
2. Triano J, Luttges M. Subtle intermittent mechanical irritation of the
sciatic nerves of mice. JMPT 1980; 3(2): 75-80.
3. Winsor, H., Sympathetic Segmental Disturbances- 11. The Evidence of the
Association in Dissected Cadaver of Visceral Disease with Vertebral
Deformities of the Same Sympathetic Segments, Medical Times,49 1-7 Nov. 1921.
4. Gore DR. Roentgenographic findings in the cervical spine in asymptomatic
persons – A ten-year follow-up. Spine 2001; 26: (22) 2463-2466.
5. Dishman RW. Review of the literature supporting a scientific basis for
the chiropractic subluxation complex. J Manipulative Physiol Ther 1985; 8:
163-174.
6. Lantz CA. The vertebral subluxation complex part 1: an introduction to
the model and the kinesiological component. Chiropractic Research Journal
1989; 1(3):23.
7. Rydevik BL. The effects of compression on the physiology of nerve roots.
J Manipulative Physiol Ther 1992; 15(1):62.
8. Kirkaldy-Willis WH. The relationship of structural pathology to the
nerve root. Spine; 9(1): 49-52.
Mel Siff:
< After all, many competitive weightlifters subject the spine to very heavy
loads which surely cause many such small (and even some large) disturbances
in every training exercise and every competition, year after year, yet the
incidence of back pain and dysfunction in this cohort is considerable less
than in the general population which never imposes that magnitude and rate of
loading.>
Comment:
True, but there are studies (eg. Videman T, Battie MC, Gibbons LE, et
al.Lifetime exercise and disk degeneration: an MRI study of monozygotic twins
MED SCI SPORT EXER 29: (10) 1350-1356 OCT 1997) that show higher rates of
disc degeneration which according to ref #4 above will lead to subsequent
symptoms and dysfunction in the future. Besides, the absence of symptoms by
itself is not a good indicator of performance or physiologic function. Also,
are there studies done with weightlifters and controls on coordination
dynamics?
Mel Siff:
<The existence of these well-known structures and processes does not
necessarily suggest that they make pathology more likely. All this means is
that the spinal complex has a very extensive and efficient cybernetic system
which ensures that the spine is well controlled over a wide range of
different conditions in space and time.>
Comment:
AMEN! But when there are problems, it makes it difficult to find the source
of the problems and to find efficient solutions. Overt pathology in many
cases takes a relatively long time to develop (eg heart disease). Sure our
systems are efficient but the trick is finding the inefficiencies (subtle)
and correcting these to prevent future problems.
Dr Mel Siff
Denver, USA
http://groups.yahoo.com/group/Supertraining/