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Larry Abraham
05-27-1993, 08:15 AM
I, too, have been following the discussion of terminology with interest and
not a little nostalgia. Herman would be proud of the resurgence of
dialogue!

I was moved to join in, though, by V. Baltzopoulos's comments about
misunderstandings of the word "contraction". PLEASE!!! Let's not refer
to activation as being eccentric, isometric, or concentric! Activation
refers to a neurally referenced event while muscle velocity is mechanically
determined, largely by external forces. I think it is very appropriate to
refer to the state of muscle as activation, but the terms isometric,
concentric, and eccentric might better be used to modify the word "action".
Even "contraction", though misleading, would be better than "activation".

With regard to R. Hinrichs's issue, I think I cast my vote for keeping only
two divisions of net joint force, as that seems to be what we can explain
and conceive most readily. Of course this should not prevent a detailed
analysis from going into greater depth, but this simpler situation should
hold the common ground on which most teaching and general work is based. I
also like the suggestions for F2 being "contact force" or "non-muscular
force". However we must be careful to recognize that much of the force
applied via ligaments and other "passive" structures was really generated
at some time by muscles. So all of these distinctions have very specific
mechanical meanings and should not be used indiscriminately (e.g. to
compare muscle vs non-muscle forces in an effort to estimate potential for
fatigue).
Larry Abraham
Kinesiology & Health Education
The University of Texas at Austin