Muscle Sculpting?

[Guest guest]

man wrote:

<If I remember right, 's work looked at specific compartments of

motor units that appeared to be preferentially activated according to

certain variables, such as joint angle, degree of rotation, etc. What I

don't recall being mentioned was the level of tension used to determine this

compartmentalization effect.

To me, and this is just a hypothesis on my part, once the tension in the

muscle gets high enough to cause hypertrophy, that effect would quickly

vanish. It makes no sense to me that, considering how force is transmitted

through the muscle and the surrounding connective tissue, the muscle could

selectively recruit " parts " of itself for one activity and not an other,

given equal requirement of force generation.

Granted that's just logical extrapolation on my part based on what I've

learned, but it seems pretty sound.

However, you'll run across a large number of gym-folk that adhere to the

muscle-shaping theory quite adamantly. This is where I've had the most

problems debating; its extremely hard to argue with someone who swears that

a preacher curl " hits the lower bicep " or that leg extensions " target the

outer quads, " etc ...... >

*** Dr Wickham in Australia, has also done work in this field and he

used to write in here periodically - maybe he would also care to comment.

also used to be on the list, so possible he will respond in due course.

Here is one of 's studies:

---------------

Eur J Appl Physiol 1998 Aug;78(3):219-25 Muscles within muscles: the

neuromotor control of intra-muscular segments.

Wickham JB, Brown JM

Dept of Biomedical Science, Univ of Wollongong, NSW, Australia.

The results indicate that the deltoid consists of seven anatomical segments

(D1-D7) based upon the distinctive arrangement of each segment's origin and

insertion. Radiographic analysis of a cadaveric shoulder joint suggested

that only the postero-medial segment D7 has a line of action directed below

the shoulder joint's axis of rotation....

To cite another example, for the latissimus dorsi we have found that the

lower segments (it was divided into six segments L1-L6 superior to inferior)

turn on first at higher contraction intensities when doing static shoulder

joint adduction movements at 90 degrees of abduction. When adduction (arm

moved towards body from the side) movements were performed with the arm

closer to the side of the body (20 degrees abduction) the more middle to

upper segments of the muscle now displayed higher contraction intensities

when compared with the more lower segments.

So, to extrapolate these results it would seem that doing lat pulldowns

emphasizing the lower phase of the movement would recruit more so the upper

to middle portions of this muscle whereas emphasing the upper phase of the

movement (arm more horizontal) would recruit more so the lower segments of

the latissimus dorsi.

Finally, for the pectoralis major we have found that only upper segments

P1-P2 (it was also divided into six segments P1-P6 superior to inferior

respectively) are activated in a static shoulder flexion (towards the front)

movement at low intensities (25% of max force) with the whole muscle being

activated at higher intensities of contraction (75%MVC). This was with the

upper limb at the side of the body. Actually, the clavicular fibres of the

pectoralis major were activated before the anterior deltoid (D1-D2) in this

flexion movement, emphasing the importance of these fibres for this

particular task.

So as a final note the results of this work .... suggest that varying

movement direction and contraction intensity does have an effect on the

outcome of which segment of the particular muscle you are training will be

recruited first and contract the 'hardest'. Something I'm sure most knew but

is scientifically validated by this work. Science catching up with

practice......

----------------

Dr Mel C Siff

Denver, USA

http://groups.yahoo.com/group/Supertraining/