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View Full Version : Unwanted tension, stiffness theory



jwright92
02-08-2006, 09:44 AM
As a follow up to my post (at the bottom) outlining my theory about using
the lack of return motion to diagnose tension, I've had a few thoughts.

The notion that unwanted tension (presumably defined as excessive antagonist
activity) interfering with technique is something that you hear
commentators/coaches refer to (informally) often. Also, my experiments on
myself seem to convince me that this is a real phenemonon. However, what's
the biomechanical justification of this. Is it purely mechanical (after the
excessive activation by the brain) or is there additional reflex inhibition.

If excess tension in the agonist/antagonist pair existed this should cancel
out and only affect maximum force, rather than impede passive return of the
joint to a neutral position after flexion or extension. Does the mere
presence of activation inhibit the passive component of the muscle/tendon
somehow?

Maybe the force-velocity curve comes into play. When the joint begins to
return, the stretching muscle (which is already active but theoretical
cancelled by the opposing muscle) is in a stronger position in the
force-velocity curve and therefore resists the return.

Or is it simply a motor control issue? Is the increase tension linked with
incorrect 'final position' targeting by the control system (so the end point
is at the extreme rather than allowing the return to neutral)?

Please help.

Joe Wright
badmintology@topracket.com
www.topracket.com/Badmintology


Original post******************
Title: Theoretical justification for return/tension relationship

I came up with a seemingly useful diagnostic tool for coaches but I would
like to strengthen up the theory behind.

The goal is to diagnose unwanted tension (as defined by counter-productive
excess antagonist activity) in a sports movement. The technique I came up
with is to use a visual cue - the 'return' after a follow through. What I
mean by 'return' is the natural return of a joint (through elasticity of
supporting muscles) to its base position after being taken to an extreme
position by the follow through.

It was in badminton smashes that I looked at this. After the racket impacts
the shuttle it follows through such that the forearm becomes pronated and
the wrist flexed. This then bounces back, or 'returns' to a more neutral
position. Through self experiments and discussion with coaches I concluded
that unwanted tension interferred with this process so that the return was
reduced or eliminated (at least temporarily) when the player was tense (e.g.
putting in too much effort).

The coaches I have talked to about this have welcomed the diagnostic
technique because it allows easy diagnosis of tension through observation of
the follow through/return.

The thing is I'm lacking a really good theoretical justification for this.
Can anyone add any weight to my theory?

Thanks

Joe