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2007/07/06, 06:38 PM
I said a while back that interesting stuff I find while doing my studies (biomechanics and human factors) I would share, and I've been greedy... There's been a lot coming up as I do my pre-reading for a class I'm taking, and I haven't been sharing.
In a series of emails with Aaron, I mentioned studies that have been done showing the relationship between muscle length and active tension.
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1271549
You have to click on each page to get a screen shot of it.
For those that don't want to, just read my post, I'll summarize it.
GEEKY STUFF:When a muscle is held in a position of elgongation (ie casting, posture while sleeping, etc), muscle length can be increased through the ADDITION OF MUSCLE CELLS in series, as opposed to the ability of each cell to stretch. This is muscle length, as opposed to muscle flexibility.
Williams and Goldspin demonstrated that when such an adaptation occurs, the muscle's length tension curve is shifted to the right.
ENGLISH: A "lengthened" muscle may be stronger while in a "stretched" position than a shorter, control muscle. However, when in a position of contraction, the lengthened muscle would exhibit a LESSER ability to exert force.
EXAMPLE: Cable pectoral fly (http://www.exrx.net/WeightExercises/PectoralSternal/CBLyingFly.html)
When doing a pectoral fly, your chest muscles are stretched out in the bottom position. Lets say you can exert 40lbs of tension in the bottom position and 45lbs in the top position. If you were to lengthen the muscles of the chest, you would be able to exert more tension in the bottom (stretched portion) of the lift, but probably less in the top portion of the lift (contracting the arms together).
WHO CARES: In physical therapy and other disciples, muscle length is VERY important. In fact, I would say that in 95% of cases of musculoskeletal pain, muscle length, activation, or strengh are to blaim. There are many instances in which a therapist will recommend certain lifts to shorten a muscle (common example is the lower back extensors) while lengthening another.
Anyone?
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Mortal by birth.
Strongman by the grace of god.
Blood Guts Sweat Chalk
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2007/07/09, 09:05 AM
One part I don't understand. So are you saying that it is possible to either shorten or lengthen a particular muscle with certain lifts? Can you give an example of a particular muscle group? Or is it more that a particular muscle (depending which it is) can be either shortened or legthened, but not both (at separate times).
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2007/07/09, 09:28 PM
Any muscle can be lengthened or shortened. However, some muscles tend to LEND themselves towards one way or the other, and this is what sometimes causes movement impairments.
For example, lets take the bicep. In an individual with a broken arm, the lower arm is often cast at a 90 degree angle to the upper arm. This puts the bicep in a shortened position. Keep that position for 6 weeks, and the muscle is shortened. However, since you can't really stretch your elbow very well, you can't lengthen it as effectively.
A common problem in woman (more common in women) with wide hips is lengthened abductors. If a women with wide hips sleeps on her side with one leg in an adducted position (stretching the outside of the hip), then that muscle can lengthen. This can lead to a variety of problems.
Another common example is the hip flexor. Due to long periods of sitting, the hip flexor becomes shortened over time. However, with long static stretching done for volume over a period of weeks, can often correct this problem.
One way to shorten a muscle (if that is the therapuetic recommendation) is to practice isometric contractions in a shortened state.
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Mortal by birth.
Strongman by the grace of god.
Blood Guts Sweat Chalk
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2007/07/09, 09:43 PM
Good stuff
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I firmly believe that any man's finest hour, the greatest fulfillment of all that he holds dear, is the moment when he has worked his heart out in a good cause and lies exhausted on the field of battle-victorious.
--Vince Lombardi
"Decide what you want, decide what you are willing to exchange for it. Establish your priorities and go to work." H. L. Hunt
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2007/07/10, 06:02 AM
very nice article wrestler...thanks much!!!
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There is no such thing as a *set point*. Im only set on getting past this point :)
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2007/07/10, 08:26 AM
Thanks for the clarification.
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2007/07/10, 12:57 PM
Glad I could help explain things. I'm still practicing my translating from physiology to english.
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Quoting from ecle5c:
Thanks for the clarification.
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Mortal by birth.
Strongman by the grace of god.
Blood Guts Sweat Chalk
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2007/07/11, 02:56 PM
Steve when are you coming back to the Rock. I thought you were only going to be gone for month.
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2007/07/11, 02:57 PM
hes trying to bulk!!
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Curl Jockeys, get outta the squat rack!
I wish everyone would get a partial amnesia and never use 'tone' ever again. (thanks Menance)
7707mutt@freetrainers.com
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2007/07/11, 05:06 PM
I was supposed to, but I've been traveling a lot. Should be back by August 14th. Good to know I've been missed.
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Quoting from Pemdas:
Steve when are you coming back to the Rock. I thought you were only going to be gone for month.
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Mortal by birth.
Strongman by the grace of god.
Blood Guts Sweat Chalk
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