On the Yahoo Supertraining group, a subscriber relayed the following story:
<I recently attended an NSCA seminar on Speed, where one of the presenters
(Ted Keating PhD) mentioned a “new” type of muscle contraction (at least new
to me). It is called an ECCONCENTRIC muscle contraction, where one part of
the muscle is shortening and the other is lengthening. The title of his
presentation was “Sprint Biomechanics”.
For example: shoulder flexion with elbow extension, where one part of the
bicep is shortening (as in shoulder
flexion) and the other part is lengthening (as in elbow extension).
Have you heard of this before? Does it go by another name? And is it good to
train certain muscles using
that principle (maybe hamstrings?). The lecturer provided no references for
his remarks. >
Mel Siff responded with the following;
*** First of all, many scientists today prefer not to refer to muscle
“contraction” and instead use the word, “action”, to minimise any of the
existing confusion about “lengthening” of muscle during eccentric action and
to eliminate the need for creation of any new such words or ideas such as
what you have just mentioned. Anyhow, what you described happens very
commonly with any muscles that cross more than one joint. Many jumps,
throws, “plyometric” drills, the so-called “double knee-bend” in the Olympic
pull, and other ballistic movements automatically invoke this sort of action,
so there is no need to do anything special to make use of it.
The speaker more accurately should have referred to one joint angle
increasing and another decreasing during the movements that he was
addressing, as is conventional for any kinesiological analysis of
bi-articular (two jointed) muscle action. It is misleading to imply that
one end of a muscle is lengthening while its other end is shortening. That
sort of curious event does not happen in a uniform, continuous elastic band
and it does not happen in a continuous muscle.
The ability of some muscles to activate locally (some work has been done in
this regard with respect to the deltoids) does not depend on local
lengthening or shortening, but as a consequence of neural excitation.
However, the act of flexing the shoulder, e.g., in a “biceps curl”, can
prestretch the elbow flexors and produce greater force at some stages of the
exercise. There is absolutely no need to use that term “ecconcentric muscle
contraction” because the entire biceps group of muscles (and some other elbow
flexors) is in concentric (or “overcoming”, as the Russians would call it)
action during that exercise. There is no such “new” type of muscle action
called ecconcentric.
Many years ago, some scientists vainly attempted to resolve all this
confusion and dissatisfaction with existing terminology by creating these
definitions:
- isometric (no external joint action evident)
- pliometric ( “eccentric” action)
- miometric (“concentric” action)
What happened? Well, someone decided that the Russians (as usual, those
crafty bearers of all the training secrets in the world!) were using a
special type of training which looked like it relied mainly on “pliometric”
action – the person/s concerned misspelled the word in the form of
“plyometrics” and that label has stuck so well that the original Russian
concept upon which it was based, namely shock method (udarniye metod), has
largely fallen into disuse in the West.
It would be preferable if that speaker and all others in future simplified
the whole muscle mechanics issue by talking about “muscle action” and dropped
all reference to contraction, ecconcentrics and any other such confounding
terminology — or at least placed inverted commas about those terms to remind
us of their limitations.
Mel Siff
