Muscle Sections Myth!

[Darkhorse]

I just replied to a post on another board entitled, "Best movements for your upper-inner chest". I thought it was a pretty good post so I'll repost here for your viewing entertainment. I added some more at the bottom as I think more about it....

In my opinion, you cannot target sections of a muscle without working the entire thing. If that was the case, you could flex your "inner" chest without flexing the entire thing. Likewise, can you flex your "inner" or "outer" biceps without flexing the whole thing? [the answer is "no" btw]

Here's a good piece of an article debunking myths like isolationalism. Source

MYTH 1. Specific portions of a muscle can be trained

The gist of this myth goes something like this, "You can hit the lower portion of your pecs with decline presses." Any statement similar to this is pure B.S. The implication is that doing decline presses will make the lower portion of your pecs larger. This is physiologically impossible. The pectoralis major are the two muscles that we commonly refer to as the chest. There are also the pectoralis minor which runs underneath the upper portion of the major. The pectoralis major, when stimulated with exercise and allowed to recover will grow. It will grow as a whole (as with all muscles), not in sections. So doing an incline, decline, or flat bench press will not make your pectoralis major grow in different fashions. The shape of your muscle is genetically determined by its origin and insertion points and no training will change this. If individual muscle cells (within a specific fiber type) grew at different rates you would have very lumpy muscles. Think about it! When selecting an exercise for a specific muscle, you should pick the one that most closely mimics the muscle's primary function (i.e. the pectoralis major's primary function is to pull the arm across the chest and downward--- so a decline press would be best amongst the presses). Another important factor in exercise selection is your own anatomy, the length of your bones and where your muscles insert and originate. Through experimentation, most experienced lifters learn which exercises work best for them.

That's also like saying some preacher curls work my "lower biceps"... Source

The Top Ten Training Myths
Myth #10: Preacher curls work the lower biceps.

First of all, there's no such thing as a "lower" biceps. It’s impossible to contract the lower portion of your biceps without recruiting any other portions.

Still not convinced? Well, you might be thinking that whenever you complete a tough set of preacher curls, you get a pump in your biceps just above the bend in your elbow. After all, it’s your "lower" biceps which creates your biceps "peak," isn’t it?

Okay, here’s the deal. The prime movers in the preacher curl are your biceps brachii and the brachialis. The biceps brachii consists of a long and short head and it crosses over two joints (your shoulder and elbow). On the other hand, the brachialis only crosses over one joint (the elbow) and it lies underneath the biceps brachii. It originates on the middle of your humerus and inserts on the radius.

When performing a preacher curl, your upper arms are placed in front of your upper body (shoulder flexion). For a muscle to be fully activated, it must be stretched at both ends. Since the biceps brachii attaches to the shoulder, it can’t be fully activated because the angle of the preacher bench places the shoulders in flexion. This places a large portion of the load on the short head of the biceps brachii and the brachialis.

Remember that the brachialis lies underneath the biceps brachii and it originates lower on the upper arm. When the brachialis gets "pumped," it pushes the bottom of the biceps brachii forward, creating what appears to be a "lower biceps."

* In my opinion, the idea of being able to work your muscles in sections is people's justification for doing a 5 day split. An example would be a "chest day", doing 3 sets of inclines for 'upper pecs', then a few sets of declines for 'lower pecs', then ending the day with some flat bench flyes for the 'inner chest'. Or worse yet, doing some high incline smith presses for the very top of your upper pecs because they're not up to snuff.

Fortunately, exercises like flat bench more than stimulate the ENTIRE chest as a WHOLE. Hence the success rate for programs like the 5 x 5 that rely on ONE compound chest movement to stimulate the entire chest!

If someone IS lagging in a certain "area" of their muscle, chances are that their entire muscle is weak. If people train like madmen to gain that ellusive "barrel chest" or a terrific sweep of their quads and come up short, it ISN'T the training....Its your parents!

That being said, if isolationalism WERE true, it would be mildly entertaining to see someone ONLY do high incline barbell presses three times a week and no other chest exercise...According to the advocates, we'd see some pretty wierd looking chests!

[_Wolf_]

this reminds me of an article i once posted:

i think this post of mine is gonna help a LOT of people... i mean, i really wish i'd read this when i was a real NEWBIE..

Originally Written by Robert DiMaggio

Isolating the upper, middle and lower pecs (chest)

This is a very common question and debated topic, personally I believe that it is not possible to isolate any part of a single muscle, i.e. the pectorial major.

The following "article" explains in great detail why this is not possible. Credit goes to Belial from another board (I do not know his real name).

The existence of the so-called "upper", "lower", "inner" and "outer" pectorals along with the assertion that it is possible to isolate one or more of these to the relative exclusion of the others in training, are among the most firmly entrenched myths in Strength Training and Bodybuilding circles. In fact none of these truly exist as either separate and distinct muscles or regions in a functional sense. Even though it could be argued that there appears to be a structural distinction between the upper and lower pectorals (and some anatomy texts do in fact support this distinction though not all do) because the pectoralis-major does originate from both the sternum and the proximal or sternal half of the clavicle along it’s anterior surface (it also has connections to the cartilages of all the true ribs with the frequent exception of the first and seventh, and to the Aponeurosis of the external oblique muscle), this is considered to be a common (though extensive) origin in terms of the mechanical function of the muscle. Thus the pectoralis-major is in fact for all practical purposes one continuous muscle with a common origin and insertion, and functions as a single force-producing unit. The terms upper, lower, inner and outer are imprecise and relevant only in order to make a vague subjective distinction between relative portions of the same muscle for descriptive purposes. They are vague and imprecise terms because there is no clearly delineated or universally defined border between them.

Further it is not physically possible either in theory or practice to contract one region of a single muscle to the exclusion of another region or regions (as a Biomechanics Professor of mine once demonstrated to a bunch of us smart-ass know-it-all’s taking his course, using EMG analysis). When a muscle contracts it does so in a linear fashion by simultaneously reducing the length of its constituent fibers and thus its overall length from origin to insertion. Even where a single muscle is separated into multiple functional units that are clearly defined such as the triceps (which are referred to as “heads” by Anatomists and Biomechanists), because they share a common point of insertion in order for one head to shorten all must shorten. This only makes sense if you think about it because otherwise there would be “slack” in one when the other shortened, which as we know does not occur. Note that there are some special cases where one head of a muscle must actually lengthen when the other shortens (e.g. the posterior head of the deltoid in relation to the anterior head during the positive stroke of fly’s), the point however is that even in these special cases there is no “slack” because there is in fact contractile activity (whether concentric or eccentric) throughout the muscle.

That is not to say however, that all fibers in different areas, or heads are necessarily shortened to the same degree during a particular movement. Depending on the shape of the muscle, the joint geometry involved, and the specific movement being performed, fibers in one area of a muscle or head may be required to shorten more or less than in others (or even to lengthen) in order to complete the required movement. For example during a decline fly though muscle fibers in all regions of the pectoralis-major must shorten as the upper arm is drawn towards the median plane of the body, because of the angle of the arm in relation to the trunk the fibers in what we commonly refer to as the lower pecs will have shortened by a greater percentage of their overall length than those in the upper region of the muscle by the completion of the movement. Conversely when performing an incline fly there is greater shortening in the fibers towards the upper portion of the muscle than in the lower.

Many proponents of the so-called “isolation” approach to training claim that this proportionally greater shortening of the fibers equates to greater tension in the “target” region than in others, and therefore stimulates greater adaptation; but this is completely at odds with the cross-bridge model of muscle contraction which clearly shows that as fiber length decreases tension also declines due to increasing overlap and interference in the area of the cross-bridges. Some also contend that the fibers called upon to shorten to a greater degree tend to fatigue faster than others and that therefore there is greater overall fiber recruitment in the region where this occurs, and thus a greater stimulus to growth; but there is no evidence to suggest that a fiber fatigues faster in one position than in another in relation to other fibers in the same muscle. In fact it has been shown that Time Under Tension (TUT) is the determining factor in fatigue and not fiber length. In fact fiber recruitment tends to increase in a very uniform fashion throughout an entire muscle as fatigue sets in.

The ability to “isolate” a head, or region of a muscle to the exclusion of others by performing a particular movement, or by limiting movement to a particular plane and thus develop it to a greater degree, is a myth created by people who wish to appear more knowledgeable than they are, and has been perpetuated by trade magazines and parroted throughout gyms everywhere. It is pure non-sense and completely ignores the applicable elements of physiology, anatomy, and physics in particular. Quite simply the science does not support it, and in most cases is completely at odds with the idea.
Regardless of the science however, many people will remain firmly convinced that muscle isolation is a reality because they can “feel” different movements more in one region of a muscle than in others. This I do not dispute, nor does science. There is in fact differentiated neural feedback from motor units depending on the relative length of the component fibers, and this feedback tends to be (or is interpreted by the brain as) more intense when the fibers in question are either shortened (contracted) or lengthened (stretched) in the extreme. However this has to do with proprioception (the ability to sense the orientation and relative position of your body in space by interpreting neural feedback related to muscle fiber length and joint position) and not tension, fatigue, or level of fiber recruitment. Unfortunately it has been seized upon and offered up as “evidence” by those looking to support their ideas by any means available.

Muscle shape is a function of genetics and degree of overall development. As you develop a muscle towards its potential, it does change in appearance (generally for the better) but always within the parameters defined by its inherent shape. A person who tends to have proportionately more mass towards the upper, lower, inner or outer region of his or her pectoralis-major will always have that tendency, though it may be more or less apparent at various stages in their development, and in most cases appears less pronounced as overall development proceeds. That is not to say that training a muscle group from multiple angles is totally without value. In fact we know that even subtly different movements can elicit varying levels of fiber recruitment within a muscle in an overall sense (i.e. in terms of the percentage of total available fibers) due to differences in joint mechanics, and neural activation patterns, as well as varying involvement of synergistic and antagonistic muscle groups involved. So by all means experiment with different angles in your training, but don’t expect to be able to correct so-called “unbalanced” muscles this way, or to target specific areas of a particular muscle. Work to develop each of your muscles as completely as possible and shape will take care of itself. If you want to worry about “shaping” you should pay more attention to the balance between different muscle groups and work to bring up any weak groups you may have in relation to the rest of your physique.

Sentinel

[Eric3237]

Good post. I think one thing that helps people believe in this (and I'm not sure if this is the exact term) is proprioception. I.E., you do some high incline flyes or something and you "feel" the tension in the upper inner pecs or at least in the upper pec area, thus leading to the conclusion you are targeting the area.

Edit* Anuj was posting at the same time. Good article, Anuj. It goes into what I was saying. Except "tension" wasn't the right word, but relative shortening of the fibers in question...

[Joker13]

Wow good post, wish I could have read it 9months ago, since I was on a 5 day split for about that long.

[Darkhorse]

Great post Anuj! That's the article I was looking for.

Anyways, here's the thread if anyone's interested in seeing the concensus -> thread

[_Wolf_]

Originally Posted by 0311

Great post Anuj! That's the article I was looking for.

Anyways, here's the thread if anyone's interested in seeing the concensus -> thread

ok cool

[Eric3237]

LOL, totally off-topic but that Louis Farakhan quote about the chicken really cracks me up.