Ecconcentric Muscle Contraction?

[Guest guest]

Joe Weissenburger wrote:

<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. >

*** 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.

Dr Mel C Siff

Denver, USA

Supertraining/