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PHYSIO  January 2002

PHYSIO January 2002

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Subject:

Re: Transversus Paradox: PP125

From:

John Spencer <[log in to unmask]>

Reply-To:

- for physiotherapists in education and practice <[log in to unmask]>

Date:

Tue, 29 Jan 2002 18:28:56 +0000

Content-Type:

text/plain

Parts/Attachments:

Parts/Attachments

text/plain (116 lines)

M.Siff:

>TRANSVERSUS ABDOMINIS ACTION
>
>Here is a quick puzzle and paradox  -  is the role of transversus
abdominis (TVA) as supremely important as some individuals have been
suggesting?  After all, the body is extremely efficient at recruiting
different systems and processes if one of the important systems involved
in a given action is injured, ill-adapted, fatigued or otherwise
compromised in its ability to offer its optimal contribution.  Not only
does this happen in the muscular system, but MRIs show that this
plasticity of function even happens in the brain.
>
>Those who work clinically often will notice how many patients with
physical differences or dysfunctions "compensate" by using different
muscles or patterns to carry out a given task without any apparent ill-
effects. One example close to home -- my paraplegic wife who is
paralysed from thoracic level T3 is able to carry out tasks that nobody
should be able to do with that level of injury, but she often does and
does so without injury.
>
>So much has been written recently about how essential transversus
abdominis is to trunk stabilisation and mobility, but has anyone ever
undertaken studies to show that people who may not be able to activate
it very effectively may compensate very effectively by using other
patterns of muscle activation and use?  Is there really any convincing
proof that "less than optimal" TVA activation definitely results in
significantly less efficient and more dangerous trunk action in all
daily activities?
>

John writes:

Certainly clinically we see that people with apparently poor TVA
activation compensate using other less appropriate muscles to try and
stabilise the lumbar spine. It is often these muscles (eg hams, hip
flexors) that become initially symptomatic as they eventually fail to
compensate for a role they are not well adapted to  carry out.

In fact the 'model' that the TVA research is based on is that of a
tripartite system (originally created by Panjabi) whereby stability of
the lumbar spine relies upon 'passive' structures (eg discs and bony
structures), 'active' structures and overall central nervous system
control.

So, for instance, if one structure fails (eg a disc becomes unstable) it
may be that the body compensates by developing bony osteophytes to try
and re-assert some 'passive' control. Of course all this compensation is
subconscious.

So yes, as you say, the body does compensate. However, clearly the
ability to  compensate is limited and at the point that the body fails
to compensate adequately we see symptoms. There are clearly many people
out in the real  world who have 'bulging' discs or considerable  OA on
x-ray who have no symptoms and others who, with the same pathologies are
riddled with symptoms. So compensation certainly occurs but when it
fails  it may be that 'conscious' intervention to activate the TVA helps
to bring the body back to a less symptomatic state.


M.Siff:

>Studies of actions other than trunk stability have shown that the same
>muscles do not necessarily become involved or become involved to the
same extent or in the same pattern in different people or in the same
person at different times (e.g., there was an article in the Scientific
American within the last 2 years which used fMRI - functional MRI to
demonstrate this).  If this happens with other movements, why should
actions involving TVA be any different?


John writes:

Interestingly, Dr Paul Hodges recently commented on research using a PET
scanner and studying TVA activation showed that the normal areas of the
motor cortex that were active with skeletal muscle activity were not
associated with TVA activity which was an early indication that the TVA
may be under distinct motor control from other muscle  groups.

The research also indicates that whilst muscles such as hamstrings,
glutes and rectus abdominus were activated in terms of both TIMING and
DEGREE of contraction DEPENDENT UPON DIRECTION OF MOVEMENT, TVA's timing
and degree of contraction was the same INDEPENDENT OF DIRECTION OF
MOVEMENT. SO, yes, there is evidence that might suggest actions
involving the TVA could  be different to other muscles.

That individuals display muscle recruitment patterns unique to each
individual is undoubted... it does not contradict TVA theory.


Mel writes:
Is there any genuine proof, other than the current conjecture,
that TVA contributions to trunk action is not as predictable and
deterministic as is being claimed by some therapists?   Does it really
matter all that much if it sometimes does not contribute as it "should"
during human movement and its decrease in function is compensated for by
other muscle actions?  Are there any references which help to resolve
this paradox?

John writes:

I think clearly that 'some therapists' out there are making
insupportable claims in respect of TVA but that doesn't negate the
convincing research that indicates this is a very exciting and promising
area of study. No-one conversant with the evidence would  deny your
assertion that the body will compensate for dysfunctional systems but
equally it is clear that the body fails to compensate adequately in all
cases hence the need for therapeutic intervention, (including TVA
activation)
>
>Dr Mel C Siff
>Denver, USA
>http://groups.yahoo.com/group/Supertraining/

--
John Spencer

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