Too much Squatting??

[Fatty4You]

Zyg, Thanks for the info about the leg extensions. I feel kinda like a dick having argued, and all the while I was the ignorant one.

Actually, my knees are kinda in pain right now. Deep squats feel ok, once i get warmed up. Acutally, I have to go deep cause otherwise, if i stop to early, too much stress on the knee. Leg extensions don't give pain symptoms, but how knows, maybe they are what are causing the pain to occur at other times.

I'll definately look up the info. If i could get my knees to stop being annoying by stopping extensions, i'd be so happy i'd have to crap my pants.

-Fatty

 

[needsize]

Dont worry about the argueing bro, as long as we keep it civil around here, that's how we learn, intelligent debate only helps us learn.

 

[Zyglamail]

Zyg, Thanks for the info about the leg extensions. I feel kinda like a dick having argued, and all the while I was the ignorant one.

Bah, dont sweat it. Argueing...or should I say debating is how we learn, the simple fact that you were willing to contend the point and continue to do so when confronted with multiple people shows your willing to learn and expand your knowledge and thats why im here. Im not right all the time either but if it werent for the fact there are people out there who want to learn, then I wouldnt need to be here and EF likely wouldnt exists.

 

[Fatty4You]

Thanks fellas.

-Fatty

 

[Fatty4You]

So, i tried to find some info on leg extensions and i found a mixed amount of info. On The T-Mag site, i found this article by Ian king:

http://www.t-mag.com/articles/179buck.html

It has this part about the knee stuff:

The overreaction in the early 90’s failed to observe more recent conclusions regarding the relative joint forces in the squat (a closed kinetic chain exercise or CKC) and the leg extension (an open kinetic chain exercise or OKC). Neitzel and Davies (10), in an excellent article regarding the benefits and controversy of the parallel squat in strength training and rehabilitation, concluded:

"When exercising from 30 degrees to 90 degrees ROM, OKC may be a better choice than CKC exercises because there may be less PFJ [patella-femoral joint] stress and more VMO electromyographic activity."

The point I’m making is that the leg extension has something to offer, and should be considered as an option and not ruled out of contention! As the statement above shows, it in fact may bring to the table a unique opportunity and benefit not offered by any other exercise!

Can anyone explain that middle paragraph to me in english? I have no idea what some of the stuff means. And, does this mean that its ok to do Leg Extensions through certain ranges of motion, but not all??

Thanks, trying to figure this all out. Hopefully, getting to understand this can help me deal with my knee problem.

-Fatty

 

[Zyglamail]

This one is more of a model study done but interesting none the less, some of the exact figures are hard to determine without the full text, but you will notice that the leg extension does cause the highest tension.

An analytical model of the knee for estimation of internal forces during exercise.

Zheng N, Fleisig GS, Escamilla RF, Barrentine SW.

American Sports Medicine Institute, Birmingham, AL 35205, USA.

An analytical model of the knee joint was developed to estimate the forces at the knee during exercise. Muscle forces were estimated based upon electromyographic activities during exercise and during maximum voluntary isometric contraction (MVIC), physiological cross-sectional area (PCSA), muscle fiber length at contraction and the maximum force produced by an unit PCSA under MVIC. Tibiofemoral compressive force and cruciate ligaments' tension were determined by using resultant force and torque at the knee, muscle forces, and orientations and moment arms of the muscles and ligaments. An optimization program was used to minimize the errors caused by the estimation of the muscle forces. The model was used in a ten-subject study of open kinetic chain exercise (seated knee extension) and closed kinetic chain exercises (leg press and squat). Results calculated with this model were compared to those from a previous study which did not consider muscle length and optimization. Peak tibiofemoral compressive forces were 3134 +/- 1040 N during squat, 3155 +/- 755 N during leg press and 3285 +/- 1927 N during knee extension. Peak posterior cruciate ligament tensions were 1868 +/- 878 N during squat, 1866 +/- 383 N during leg press and 959 +/- 300 N for seated knee extension. No significant anterior cruciate ligament (ACL) tension was found during leg press and squat. Peak ACL tension was 142 +/- 257 N during seated knee extension. It is demonstrated that the current model provided better estimation of knee forces during exercises, by preventing significant overestimates of tibiofemoral compressive forces and cruciate ligament tensions.

Next we have another abstract which simply states the open loop exercise(leg extension) causes more anterior tibial displacement(which equates to more shear force).

A measurement of anterior tibial displacement in the closed and open kinetic chain.

Jenkins WL, Munns SW, Jayaraman G, Wertzberger KL, Neely K.

Department of Physical Therapy Education, School of Allied Health Sciences, East Carolina University, Greenville, NC 27858, USA.

Anterior displacement of the tibia during knee extension movement has been identified as a possible factor in anterior cruciate ligament (ACL) reconstruction failure due to the increased stress placed on the graft, leading to a creep response in the healing graft. Nineteen healthy subjects with a unilateral ACL deficiency were evaluated in an open and closed kinetic chain. A KT-1000 was used to measure anterior displacement of the tibia on the femur during isometric open and closed kinetic chain exercise at 30 and 60 degrees. An analysis of variance for repeated measures followed by Newman-Keuls multiple comparison tests were performed to determine the differences between the open and closed kinetic chain for the involved and uninvolved knee. Statistically significant differences were found when comparing the amount of anterior displacement between the open and closed kinetic chain for the involved and uninvolved knee at 30 and 60 degrees. Clinicians utilizing isometric exercise in rehabilitation of the anterior-cruciate-deficient and the anterior-cruciate-reconstructed patient should be aware of the increased amount of anterior tibial displacement when comparing open and closed kinetic chain exercise.

yet another....

Comparison of closed and open kinetic chain exercise in the anterior cruciate ligament-deficient knee.

Yack HJ, Collins CE, Whieldon TJ.

Department of Physical Therapy and Exercise Science, State University of New York, Buffalo 14214.

The purpose of this study was to quantify the amount of anterior tibial displacement occurring in anterior cruciate ligament-deficient knees during two types of rehabilitation exercises: 1) resisted knee extension, an open kinetic chain exercise; and 2) the parallel squat, a closed kinetic chain exercise. An electrogoniometer system was applied to the anterior cruciate ligament-deficient knee of 11 volunteers and to the uninvolved normal knee in 9 of these volunteers. Anterior tibial displacement and the knee flexion angle were measured during each exercise using matched quadriceps loads and during the Lachman test. The anterior cruciate ligament-deficient knee had significantly greater anterior tibial displacement during extension from 64 degrees to 10 degrees in the knee extension exercise as compared to the parallel squat exercise. In addition, the amount of displacement during the Lachman test was significantly less than in the knee extension exercise, but significantly more than in the parallel squat exercise. No significant differences were found between measurements in the normal knee. We concluded that the stress to the anterior cruciate ligament, as indicated by anterior tibial displacement, is minimized by using the parallel squat, a closed kinetic chain exercise, when compared to the relative anterior tibial displacement during knee extension exercise.

 

[Fatty4You]

Hey zyglamail, great post man. Thanks for the info.

So, from what i am gathering, the lower part of the leg extension is bad, like below 60 degress or so. But, do you think its ok to use the LE to do some small ROM movements at the top of the extension to really get a good squeeze? I dont really get the best squeeze on squats or leg press cause i dont want to lock out my knees, but i figure on the leg press, there no downward weight [through the knee] so doing some lockout there to work that range would be beneficial.

I figure, when it comes to the body, Form Follows Function, so if i want to be strong at the top, i got to work at the top???

-Fatty

 

[Zyglamail]

Fatty4You, as I mentioned, I dont think the extension is a bad exercise, just not the best for the knees or for mass. The main reason for me posting these abstracts was to simply dispell the myth that squats were hard on the knees. SO many people avoid them and stick to extensions and curls because they heard squats were bad for the knees. However, if you take just about anyone they can squat a lot more weight(especially considering they have their own body weight to lift as well) than they can do on the leg extension and even with significantly less weight the leg extension puts more stress on the joint.

If your knees are in good shape the leg extension should not cause a problem for you.

In the estension, unless I am totally reading thing wrong(hehe been known to happen, especially in the morning) you are going to have the most sheering for when the leg is straight. You have support under the back of the upper thigh and weight on the front of the shine pressing down. The weight distribution is not directly into the socket of the knee, but sideways stresses. In the squat the weight is bearing down on the upper body and pressing the joint together at full contraction.

 

[Fatty4You]

I think my biggest problem with all this stuff is, is that i just dont understand what a Shearing force actually is. I have tried to find it, but i pretty much just come up with stuff like "A shearing force is a force the causes an object to change its shape." Now, how does that apply to the knee - i have no idea. But i keep seeing in reference to the knee.

And as for good knees. My left knee hurts. I have notices, the when i do leg extensions currently, i feel the pain near the starting position, but the pain goes away once my leg straightens out.

As for squats, i feel the pain at about a little above parallel, then once i drop below parallel, the pain is gone.

As for how this affects me, aside from PISSING Me off!! it deosn't really affect me to bad. I can still do most things, i just can't use as much weight. But i am having my knee looked at by my chiro and hopefully, one day, it will be better.

-Fatty

 

[Zyglamail]

SImply put what I am referring to is more or less a direct sideways force. In other words if you put a board in a vice so it could not move (ie your upper leg against the seat of a left ext machine). Now press the far end of the board sticking out of the vice and you will see a gradual bend over the whole distance on the board sticking out. Now if you apply pressure right above where the vice has the board clamped the force is no longer spread through the entire length of the protruding part of the board and in turn most of the stress is right where the board is clamped in the vice. Those are two extremes and the leg extension is somewhere between, there is a direct cross ways force applied to the knee when the leg is extended because the upper leg is imobile(for the most part) and you are pressing down on the front of the shin with weight. In a squat you are applying pressure down and its supported under the foot with the joint in the middle (ie closed loop).