Another way to approach this problem might be to consider the effects
of overt muscular weakness on posture. For example, a distinct set of
clinical features are evident in patients with Duchenne-type Muscular
Dystrophy (DMD); a disease characterised by progressive weakness and
wastage of muscles in a (typically) symmetrical pattern, beginning
proximally in the pelvic and shoulder girdle, and trunk. In DMD,
characteristic postural changes occur in association with progressive
weakening of muscles, including "postural" muscle groups, ie. those
responsible for postural maintenance. Scoliotic deformities are
common, resulting from the unopposed effect of gravity in the upright
position, and these may eventually be so severe as to interfere with
respiratory function.
Postural changes in DMD have been well-documented, and any good
paediatric PT textbook may be consulted for more detail.
In our quest for the link between "strength" and "posture", possibly
there exists a point along the continuum at which further increases in
"strength" (alone) of those stabilising/postural muscle groups will not
result in any measureable improvements to "optimal posture", and that,
instead, other factors (eg. neuromuscular, structural, cognitive)
become increasingly more important...
John Gruhn
Physiotherapist
Cairns, Australia
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>From [log in to unmask] Thu Sep 3 11:07:42 1998
Date: Wed, 2 Sep 1998 21:00:22 EDT
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Subject: STRENGTH & POSTURE
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In a message dated 9/2/98, Barrett Dorko< [log in to unmask]> wrote:
>I'm interested in seeing if anyone amongst you can come up with a reference
that correlates muscular strength with posture. I've never seen a study
verifying this, but I'm trying to remain open-minded.
***Has anyone really suggested this? This correlation seems to suggest that
the simple act of holding a given unloaded posture increase strength,
something that is difficult to accept. All research and practical experience
has shown that increase in strength depends on the imposition of progressively
heavier loading on the body.
Certainly, any changes in posture required to enable one to prevail over heavy
loads will increase strength and power, but maintenance of a given static
unloaded posture cannot (unless one is imposing electrostimulation on the
muscles at the same time).
Possibly Dorko was really asking the reverse of that 'correlation', i.e. if
anyone had seen references which imply that optimal posture maintenance is a
function of strength, so that a stronger person would be better equipped to
hold a given posture. Even if this interpretation of 'correlation' is
suggested, strength is a function of neuromuscular activation - and 'correct'
patterns of postural management may be produced by weaker and stronger
individuals. Since a great deal of postural maintenance is also a function of
ligamentous involvement, the picture can hardly simplified to that extent.
Greater strength, however, might enable someone to hold a given less efficient
posture for longer without causing undue stress or damage, provided that the
appropriate muscles are activated at the time. In other words, a little extra
functional strength (what in engineering may be regarded as building a certain
'safety factor' into a system) cannot go amiss.
Whichever way round that 'correlation' is implied, I am curious to see what
others have written about this interesting topic.
Dr Mel C Siff
Littleton, Colorado, USA
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