This article discusses stress relating only to joint moments at the knee and not the entire system and it also stresses in its conclusion limiting terminal joint flexion (ie less of it, albeit the article is geared towards clinicians and not S&C;work).
If your article is referencing peak posterior force data, you might want to put that reference on display as well. I would certainly agree with loads of the same mass that peak posterior forces would be higher the deeper the squat, but I am not discussing the external loads of the same mass am I?
Please be critical of what of you read in research journals before you post about it and pay attention to the audience and what it states. Also, be mindful I am relating stress to external load and not stress at joint moments as that is an entirely different subject and thread. Also, please don’t take out of context my posts and if you are going to be critical with them as least relate them to my points of reference and not one of a different point of reference.
Well, I was not only replying to your comment I was posting studies about squatting in relation to the original post. The article discusses stresses at knee joint, but it is stress nonetheless. I’m aware that you are relating stress to external load, but you are failing to take into account internal work done (i.e. the potential and kinetic energy permutations within body segments and work done by or on muscles). So you could relate that to the aforementioned study and conclude that one is completing more work by completing a greater ROM in full squat vs. 1/4 squat.
Here is that other study:
Takeo Nagura, Chris O. Dyrby, Eugene J. Alexander, Thomas P. Andriacchi *
Division of Biomechanical Engineering, Department of Mechanical Engineering, Stanford University, Durand Building, 227 Stanford, CA 94305-3030, USA
There is a lack of fundamental information on the knee biomechanics in deep flexion beyond 90°. In this study, mechanical loads during activities requiring deep flexion were quantified on normal knees from 19 subjects, and compared with those in walking and stair climbing. The deep flexion activities generate larger net quadriceps moments (6.9-13.5% body weight into height) and net posterior forces (58.3-67.8% body weight) than routine ambulatory activities. Moreover, the peak net moments and the net posterior forces were generated between 90° and 150° of flexion.
The large moments and forces will result in high stress at high angles of flexion. These loads can influence pathological changes to the joint and are important considerations for reconstructive procedures of the knee. The posterior cruciate ligament should have a substantial role during deep flexion, since there was a large posterior load that must be sustained at the knee. The mechanics of the knee in deep flexion are likely a factor causing problems of posterior instability in current total knee arthroplasty. Thus, it is important to consider the magnitude of the loads at the knee in the treatment of patients that commonly perform deep flexion during activities of daily living. © 2002 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved.