John Spencer<[log in to unmask]> writes:
< Dysfunctional TVA is not defined AT ALL by an inability to produce a
contraction of the muscle.
Dysfunctional TVA is defined by it's inappropriate recruitment in terms of
TIMING in that, instead of activating in advance of other muscles (eg
shoulder muscles in a throwing motion), it activates late, thereby
proving unable to adequately stabilise the lumbar spine. ...>
*** You are resorting to semantic manoeuverings again. I did not spell out
the many nuances of motor action associated with TVA or any other form of
functioning every time that I mentioned the process, simply because we should
all be very aware of these on this professional list. Instead, I usually
referred to the "efficient" functioning of these muscles, a process that
involves contraction magnitude, duration, timing of all tension variations,
point of peak tension production, pattern of activation, rate of force
development and diminution, mean power, peak power and many other descriptors
of muscle activation. To remind you, here is an example of what I wrote:
" However, I am suggesting that future findings may well show that anyone who
regularly trains with weightlifting and powerlifting derived variations will
automatically acquire the ability to EFFICIENTLY use TVA and MTF (even though
static clinical tests may suggest some 'deficiencies' under non-sporting
conditions).
You should note, however, that your following comment implies that a muscle
either activates or does not in some sort of all-or-none contraction process.
The concept of timing cannot be used outside the context of how a muscle
activates; one has to refer to key biomechanical features associated with
that "timing", such as timing taken to produce peak force (not necessarily
peak EMG, because magnitude of EMG does not necessarily relate to efficient
peak force production).
<Dysfunctional TVA is defined by it's (sic) inappropriate recruitment in
terms of TIMING in that, instead of activating in advance of other muscles (e
g shoulder muscles in a throwing motion), it activates late.>
That implication is entirely incorrect, because gross muscle action is graded
and it takes a given amount of time to reach any magnitude of tension and a
specific amount of time to reach maximum tension peaks on the muscle
activation curve. The ability of any muscle to contract instantaneously
contradicts basic laws of thermodynamics and the concept of a muscle firing
instantaneously from a quiescent state needs to be laid to rest immediately.
<<In fact personal comments from the researchers suggest that those
individuals that tried to rehab TVA by using explosive, high resistance
movements actually resulted in WORSE timing of TVA and more pain and
dysfunction.>
*** Which exercises were used and how was the rehabilitation carried out?
Any references other than this anecdote?
Dr Mel C Siff
Denver, USA
http://groups.yahoo.com/group/Supertraining/
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