Targeting parts of a muscle??

[Fatty4You]

I was hoping someone could explain this to me. I read lots of places, including fitness Textbooks, that certain exercises work certian parts of the muscle. For example, i read that dumbell flys work more the outter part of the chest.

But from what i have learned, a muscle fibril is made of linked sacromeres. When a fibril contracts, ALL sacromeres in it contract at the same time and i believe to the same extent.

To me, this would seem like no matter what exercise you do, if you contact a particular fibril, you contract the whole thing, not just parts closer or farther from the insertion point. So, how could this allow for hitting specific areas of a muscle.

Trying to come up with answers, i thought that maybe different fibers are contracted at different angles, certainly they are different fibers contracted with different weights.

But i am not sure what the actual reason is. I know from personal experience, that i feel dumbbell flys in different parts of my pec than i do from barbell press, but i want to know why???

Any suggestions?

-Fatty

 

[epimetheus]

Well, most muscles have more than one head. Different exercises can contract heads at different levels of intensity. Therefore it is best to do different lifts to make sure the heads are all getting full stimulation.

As an addenum, I must state that the chest has only two heads, the outer or inner not being them.

 

[argent]

You are correct fatty. Muscles can only contract in the direction of their fiber arrangement. For instance, the biceps only main job is elbow flexion. It flexes the elbow, thats it unless you want to talk about supination in which it is an accesory muscle. So any excercise which causes elbow flexion will work the biceps in the same manner. This is assuming the trainee doesn't cheat on one exercise or another and their form is perfect.

 

[casualbb]

You are correct fatty.

I second that!

But i am not sure what the actual reason is. I know from personal experience, that i feel dumbbell flys in different parts of my pec than i do from barbell press, but i want to know why???

They're simply different motions. DB flyes are an isolation; BB press isn't. I wouldn't put much stock in how it feels.

-casualbb

 

[bignate73]

As an addenum, I must state that the chest has only two heads, the outer or inner not being them.

HELL YEAH!

 

[Fatty4You]

Ok guys, i see what you are saying. I can understand the different head stuff.

Actually, i recently was studying the muscle of the back of the leg, specifically the hamstring. The hamstring is constructed of the biceps femorous and the semimembranosus and teh semitendonosus [spellings??]. But anyway, it turns out that the biceps femoris has a long head and short head. Incedentally, the short head is NOT a two joint muscle. THat is, it attaches to the lower leg with its origins on the upper leg, not the ischial tuberosity or whatever.

What does this mean?? It means the short head of the hammy is NOT getting worked in stiff leg dead lifts because it doesn't have to contract [other than to perhaps stabilize]. So, to me, this means lying leg curls are essential to work the short head of the biceps femoris.

I only bring this up because many people laugh at the lying leg curl saying that it is a waste of time.

Just something to think about...

-Fatty

 

[Rich_S]

For muscles that are multi-headed, you can target individual heads (though you can never totally isolate only one head). You cannot however, target different sections of a muscle head. Anyone who tells you that you can isolate the inner chest or the peak of the biceps is an idiot.

 

[louden_swain]

For me certain exercises work better than others. For example, when I perform incline presses I can feel the pain throughout the entire chest. Flat bench on the other hand fails to do this.

 

[Gladiola]

Interesting post. I suppose this would apply to the abs as well. Being that so many women want to work 'lower abs' If you do a move that works rectus abdominus, you work that entire rectus abdominus - you can't isolate the lower packs on the 6-pack, right?!

 

[Rich_S]

Interesting post. I suppose this would apply to the abs as well. Being that so many women want to work 'lower abs' If you do a move that works rectus abdominus, you work that entire rectus abdominus - you can't isolate the lower packs on the 6-pack, right?!

Well, you can think of the abs as being multi-headed because of the tendons that make up the "6 pack". My point was that from tendon to tendon, you can't target part of a muscle. But with the abs, it's really almost different heads of the muscle. Though I don't think you can totally isolate upper or lower abs.