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TPT
07-27-2009, 11:51 PM
why the heck do we have asymmetrical muscular development of our legs or simply one side of the body compared to the other. well their are many reasons likely neurological and orthopaedic. the following study by flanagan and salem (2007) provided some insight to what might be occuring as we train.


Bilateral Differences in the Net Joint Torques During the Squat Exercis (http://forums.rxmuscle.com/nsca-jscr/Abstract/2007/11000/Bilateral_Differences_in_the_Net_Joint_Torques.41. aspx)

FLANAGAN, SEAN P.; SALEM, GEORGE J.
The Journal of Strength & Conditioning Research. 21(4):1220-1226, November 2007.

BILATERAL DIFFERENCES IN THE NET JOINT TORQUES DURING THE SQUAT EXERCIS. that there are no b...

Abstract:

Bilateral movements are common in human movement, both as exercises and as daily activities. Because the movement patterns are similar, it is often assumed that there are no bilateral differences (BDs; differences between the left and right sides) in the joint torques that are producing these movements. The aim of this investigation was to test the assumption that the joint torques are equal between the left and right lower extremities by quantifying BDs during the barbell squat. Eighteen recreationally trained men (n = 9) and women (n = 9) completed 3 sets of 3 repetitions of the squat exercise, under 4 loading conditions: 25, 50, 75, and 100% of their 3 repetition maximum, while instrumented for biomechanical analysis. The average net joint moment (ANJM) and maximum flexion angle (MFA) for the hip, knee, and ankle as well as the average vertical ground reaction force (AVGRF) and the average distance from the ankle joint center to the center of pressure (ADCOP) were calculated. Group mean and individual data were analyzed ([alpha] = 0.05). At each joint, there was a significant main effect for side and load, no main effect for gender, with few significant interactions. The hip ANJM was 12.4% larger on the left side, the knee ANJM was 13.2% larger on the right side, and the ankle ANJM was 16.8% larger on the left side. Differences in MFAs between sides were less than 2 degrees for all 3 joints (all p >= 0.20 except for the knee at 75% [p = 0.024] and 100% [p = 0.025]), but the AVGRF and the ADCOP were 6% and 11% larger on the left side. Few subjects exhibited the pattern identified with the group mean data, and no subject exhibited nonsignificant BDs for all 3 joints. These findings suggest that joint torques should not be assumed to be equal during the squat and that few individual subjects follow the pattern exhibited by group mean data.
(C) 2007 National Strength and Conditioning Association

Go to Full Text of this (http://forums.rxmuscle.com/nsca-jscr/Abstract/2007/11000/Bilateral_Differences_in_the_Net_Joint_Torques.41. aspx)


the experimenters tested whether the joint torques of the right and left legs were the same or different.

interestingly, weight of the barbel did not effect the asymmetry in kinematics. we might have thought that as the load increased, more compensations or changes in mechanics would occur. well that didnt happen. if you had a left sided preference, that is what occured no matter how much you lifted.

these data provide us with empirical support to joint mechanical differences of the right and left legs during squats. a strong assumption is that we have bilateral differences in joint movements during most bilateral exercises including presses and pulls.

might this be why many of us have one leg smaller than the other?

Frosty
07-28-2009, 12:15 AM
Would this indicate the need for single leg work as well as single arm presses and pulls for the weaker extremity?

militantmuscle
07-28-2009, 01:18 AM
Definitely. You could incorporate this during breaks off of most HIT cycles, or a 'deload' from slingshot training.

For example, let's say you did 4 weeks DC/HIT or STS. During your 1-2 week break, only exercise weak parts, or weak sides 1-3x a week.

TPT
07-28-2009, 08:58 AM
these results might indicate our susceptibility for injury. though the paper did not show that increasing loads would increase differences in our bilateral mechanics, it is plausbile to suggest increased risks of injury with larger loads. add the repetitive nature of our exercise regimens- we're screwed!

unilateral training is recommended. for mutlijoint exercises and single.

their might be a larger function for machine exercises than free weights for these cautious occasions since we may limit "joint degrees of freedom" or stabilze joints we prefer not to move. what do you think?

do others "feel" differences of our right and left sides during presses or pulling exercises? even during leg presses i have a differences in left and right mechanics.

Frosty
07-28-2009, 08:24 PM
You mean like 1 leg leg-press vs. say lunges?

Why is it that I hate lunges? They just seem to make my ass and adductors sore. I'd rather squat until I almost pass out than ever do a single lunge again in my life. I hate lunges.

TPT
07-28-2009, 10:03 PM
You mean like 1 leg leg-press vs. say lunges?

Why is it that I hate lunges? They just seem to make my ass and adductors sore. I'd rather squat until I almost pass out than ever do a single lunge again in my life. I hate lunges.


dont front, you probably perform those ass blaster machine exercises! lol.

anyway, when performing free weight multijoint exercises like squats- we might be causing more problems long term because their are so many joints "free." at rest we have subtle postural mal alignments.

now imagine a huge load on our backs as we move and still have mal alignments. those kinematic abnormalities plus abnormal forces because of the large loads equals- we're screwed!

however, when performing leg presses we greatly control for joint movements by stabilizing them. e.g., our spine is controlled from rotating while our lower extremity joints are more likely to stay in the sagital plane.

what do you think?

Frosty
07-28-2009, 10:11 PM
dont front, you probably perform those ass blaster machine exercises! lol.

anyway, when performing free weight multijoint exercises like squats- we might be causing more problems long term because their are so many joints "free." at rest we have subtle postural mal alignments.

now imagine a huge load on our backs as we move and still have mal alignments. those kinematic abnormalities plus abnormal forces because of the large loads equals- we're screwed!

however, when performing leg presses we greatly control for joint movements by stabilizing them. e.g., our spine is controlled from rotating while our lower extremity joints are more likely to stay in the sagital plane.

what do you think?


Sounds like something I could do as well. I know my left quad isn't as good as my right. Now if you were to prescribe left leg lunges I would have probably ignored it but this is something that sounds like a very good idea to me.


Now what about hamstrings? Single leg deadlifts? Or deadlifts with the dominant leg back a couple feet or so from the weaker leg so that you maintain stability better than using a single leg? Single leg glute-ham raises?? (JK!!! Maybe if you don't like where your hamstring and gastroc tendons are attached)

Frosty
07-28-2009, 10:12 PM
dont front, you probably perform those ass blaster machine exercises! lol.


Haha dude I have a huge ass. I try to avoid anything that stimulates my ass muscles to any significant degree. It's muscle, but it's a big muscle. Black chicks love it, though.

Frosty
07-28-2009, 10:46 PM
The Rapist,

What about innervation issues? Could it be possible that a spinal subluxation could possibly mess with the nerves feeding a limb? Perhaps a good chiropractor could make sure things are in order to make sure that the single leg training being done will actually be effective. Just an idea.

TPT
07-28-2009, 10:55 PM
Sounds like something I could do as well. I know my left quad isn't as good as my right. Now if you were to prescribe left leg lunges I would have probably ignored it but this is something that sounds like a very good idea to me.


Now what about hamstrings? Single leg deadlifts? Or deadlifts with the dominant leg back a couple feet or so from the weaker leg so that you maintain stability better than using a single leg? Single leg glute-ham raises?? (JK!!! Maybe if you don't like where your hamstring and gastroc tendons are attached)


unilateral leg extensions followed by unilateral leg presses for quads. and hamstring curls followed by leg presses.

when i perform deadlifts, im always in front of the mirror. i used to care about moving crazy weights until i saw myself and noticed one of my arms closer to the floor. my trunk was rotated in acent and descent! that couldnt be good.

also, when performing side laterals i have a tendency to have my right arm more forward. not good.

everyone, watch out for these asymmetries during movements!

TPT
07-28-2009, 10:59 PM
Haha dude I have a huge ass. I try to avoid anything that stimulates my ass muscles to any significant degree. It's muscle, but it's a big muscle. Black chicks love it, though.



ehh maybe. though i know i love them. and they love long hair. lol.

Frosty
07-28-2009, 11:02 PM
ehh maybe. though i know i love them. and they love long hair. lol.

My hair used to be way longer than yours....and yeah, black chicks often dug it. Women either loved it or hated it. My native american friend said I used to look like a warrior with long hair and then I looked like a punk when I cut it lol.

TPT
07-28-2009, 11:11 PM
The Rapist,

What about innervation issues? Could it be possible that a spinal subluxation could possibly mess with the nerves feeding a limb? Perhaps a good chiropractor could make sure things are in order to make sure that the single leg training being done will actually be effective. Just an idea.


it is plausible. anything causing impingement to nerves would cause problems including subluxatioins, herniations, etc.

also, muscles themselves may cause innervation problems!

something called double crush or mutltiple crush syndrome exists where nerves are entrapped at different sites causing neural symtoms similiar to what is found in carpel tunnel syndrome.

Frosty
07-28-2009, 11:13 PM
it is plausible. anything causing impingement to nerves would cause problems including subluxatioins, herniations, etc.

also, muscles themselves may cause innervation problems!

something called double crush or mutltiple crush syndrome exists where nerves are entrapped at different sites causing neural symtoms similiar to what is found in carpel tunnel syndrome.


Is this something ART can help with? If not, what is treatment for crush syndrome?

TPT
07-28-2009, 11:41 PM
Is this something ART can help with? If not, what is treatment for crush syndrome?


a lot going on in the literature. but, prevention is key. we have to make sure our joint ranges our normal because they are indicators of whether our muscles are providing abnormal forces on our bone structures. make sure we have perfect alignment as we have spoken about previously. and make sure our muscles are not tight where they would entrap nerves. activities like stretching, yoga, and masages help keep muscles from being too tight.

as far as a.r.t., i have my discretions because similar to chropratic it lacks empirical support and validation.