Upper abs, lower abs. Upper pecs, lower pecs.

[dragontounge2]

The Abs are genetic ex. six pack four pack

[dragontounge2]

The upper pec is also an insertion with the deltoid.

[IronFist]

Originally posted by Sharky
well?

Ok, chill out

It must be your imagination or something. Or maybe you've stressed other, smaller muscles around the abs that you mistaking for abs... hip flexors are common in this case.

IronFist

[Royal Dragon]

Like I said in the other thread, Hip Flexors = Lower Abs to the Layman.

[Sharky]

By the way, i feel the need to point out that i already knew this, but it's what everyone asks whenever i tell them that it's one muscle.

I had to post this otherwise i might not look like the don that i am.

[Kristoffer]

Uhm.. yeah I know that too

[PLCrane]

I just want to point out the the picture that was provided to prove that the rectus abdominis is one muscle clearly shows it as two muscles - one on the left, and one on the right.

So what does the rectus abdominis do during side-bending? Does half do a concentric contraction while the other half an eccentric contraction?

I think it is possible to contract separate portions of the rectus abdominis when it's in an unloaded position. Just sitting here upright in my chair, I can do it. Leaning back to put some load on it causes the whole thing to work. I don't think there's any way to do significant work (like a sit-up) with anything but the whole muscle at once.

While we're on the subject, how many muscles is the pubococcygeus, and how many of us can selectively contract the left and right halves?

[IronFist]

If the abs were two seperate muscles (divided vertically), then they would have two seperate names.

Nice try, though.

IronFist

[PLCrane]

Originally posted by IronFist
If the abs were two seperate muscles (divided vertically), then they would have two seperate names.

Like left rectus abdominis and right rectus abdominis, for instance?

This one is from Duke University. Scroll down to linea alba -
http://216.239.53.100/search?q=cache...hl=en&ie=UTF-8

I hope you know I agree with you regarding abs training.

Take care,
PLC

[IronFist]

Well, I'm not exactly sure what that website was talking about, but here's what it said:

..elastic ligaments between arches limit flexibility of column linea alba where aponeurosis joins again and joins mirror-image counterpart separates left and right Rectus Abdominis Longissimus part of Erector Spinae - connects

So I think they're talking about something else?



IronFist

[PLCrane]

Um, I think the formatting got crunched going from pdf to html. You got a piece of ligamentum flavum and a piece of longissimus mixed in with your linea alba.

I think it's supposed to look like this -
"linea alba - where aponeurosis joins again and joins mirror-image counterpart separates left and right Rectus Abdominis"

Still not gramatically correct, but it does make sense.

Here's a better picture of the linea alba and the tendinous inscriptions, showing that the rectus is made up of of separate sections of muscle fibers joined together with connective tissue. All the sections on the left are innervated by the left side nerves, and all the sections on the right are innervated by right side nerves, just like all the other bilateral pairs of muscles in the body.
http://summit.stanford.edu/ourwork/P...img/CA-461.jpg
But unlike all those other pairs, the left and right rectus are joined down the middle and work in unison. So we just talk about one.

I'm pretty sure nobody ever talks about a left or right rectus exept maybe when there's a paralysis on one side. That could occur with damage to the nerves on one side from a spinal injury, for instance.

[IronFist]

PLCrane, good picture!

To the best of my knowledge, they're still connected under the linea alba. This makes it one muscle.

IronFist

[PLCrane]

http://www.unc.edu/~mackin/chapter6b63l.html
Linea alba is on the midventral line of all vertebrates and separates myomeres of left and right sides of the body

http://www.udallas.edu/biology/Brown...e%20Types.html
Raphe--junction of two muscles at a band of connective tissue to form a line of fusion, such as the linea alba

http://www.biologie.uni-hamburg.de/b.../highli07.html
ANTERIOR ABDOMINAL WALL: The anterior abdominal wall muscles consist of a) three layers of flat muscles, the tendons or aponeuroses of which converge on the midline or linea alba and b) a vertically oriented pair of muscles, which are incompletely sheathed by those aponeuroses (rectus sheath).

The flat muscles (external oblique, internal oblique, and transversus abdominis) arise from the lateral aspect of the torso. This muscle wall protects the abdominal viscera. These three muscles act to compress the abdominal contents (i.e., raise intrabdominal pressure) during expiration, urination, defecation, and assist in maintaining pressure on the curve of the low back, resisting lordosis (sway back).5

And here's a page with a cross-section, showing the tendon between the two bands of the rectus (they only labeled one side - #4)
http://anatomy.uams.edu/htmlpages/an...section26.html

And incidentally, I just learned that a bovine rectus abdominis is a flank steak. Maybe you could get your local butcher (if there are any left) to show you a whole one.

[Oso]

ok, so...the reason I can do more leg lifts than sit ups or crunches
is because there are other muscles helping out on the leg lifts???

Today I did 3 sets of 50 crunches intervalled with 3 sets of 50
6" to 45 degree leg lifts and burned out on the crunches
but could have doubled the number of leg lifts easy.

Also, I can do more crunches vs. full sit-ups.

I have operated under the concept that a full sit-up releases
tension at the top of the movement and therefore you get
a better burn by doing good crunches (this meaning that most
people who just lift their heads or at most the shoulder blades
are NOT doing a full crunch.) So, why is it harder to do a full
sit-up then a good full-crunch*

curious...sounds like IF and PLcrane have spent a lot of time
looking at this...

matt

*Full Crunch--curling the head towards the naval until the middle
to small of the back is off the floor.

[PLCrane]

Originally posted by Oso
ok, so...the reason I can do more leg lifts than sit ups or crunches
is because there are other muscles helping out on the leg lifts???

Yes. Ilio-psoas is the main hip flexor, with some help from rectus femoris (middle and longest of the quads). Be careful that you don't let your lower back hollow too much when you're doing the leg lifts, it's bad for the joints in the lower part of the spine.


I have operated under the concept that a full sit-up releases
tension at the top of the movement and therefore you get
a better burn by doing good crunches (this meaning that most
people who just lift their heads or at most the shoulder blades
are NOT doing a full crunch.) So, why is it harder to do a full
sit-up then a good full-crunch*

Maybe. I think you're more of an expert on it than I am, because you've obviously done a lot more situps than I ever have.

My preference is to do sit-backs. You start sitting up, let yourself back 1/4 of the way and hold for 20 seconds, go to halfway back and hold another 20, then go 3/4 and hold, then sit up again. You never go all the way back. I also like to do this at an angle - looks kinda like a flying side kick on the ground. Take my picture and we'll cut it out and stick it onto a picture of the sky between two mountains.


PLC