June 20, 2007
Popular Biomechanics, by Mark Rippetoe - Mar 07 CFJ
The most useful theories are those that simplify our understanding of apparently complicated things. The theory of evolution explains the rather interesting fact that frogs and humans both have two forearm bones, that grasshoppers and catfish share the common pattern of repeated trunk segmentation, and that all of us, including bacteria, use pretty much the same high-energy phosphate system to move things around inside our cells. My observations will never be this profound, interesting, or important. They will not even be that original. But since you apparently have nothing better to read right now, let’s just enjoy these next few minutes together as though they will be useful.
Barbell training has been the focus of my attention for the last couple of decades. I am not bored with it yet. Whenever I have the opportunity to train a group of interested, motivated, bright people, I learn as much as they do. It has recently come to my attention that there are objective ways to describe proper form for the basic barbell exercises that are valid for everybody who does them, regardless of their anthropometry. For example, it doesn’t matter how long your femurs or how short your back, the bar is going to come off the ground in a deadlift when the bar is directly under the shoulder blades. (For a detailed discussion of the deadlift, see my CrossFit Journal article "A New, Rather Long Analysis of the Deadlift.") This position will place the shoulders slightly forward of the bar and the arms at a slight angle back to it. This is a function of the mechanics of the skeleton, and is true even when form is bad: if the bar is too far away from the shins, and not right against them in a position that minimizes the torque against the hip joint, the bar still leaves the ground from a position plumb to the scapulas.
This entire article is available in the CrossFit Store.
Read a biomechanics article... The knees should not pass the toes when doing squats.
Jason,
You didn't pick that up from a biomechanics article; you learned it from a dimwitted aerobics instructor who likely struggled with geometry and certainly had no exposure to biomechanics. The notion that the knees shouldn't pass beyond the toes is biomechanical nonsense. You are an arrogant fool. What you describe is impossible for most people's geometry. Stick around and learn something.
Welcome to CrossFit.
"You are an arrogant fool"
What a nice, welcoming environment.
Coach has a point though-so many people are taught that the knee should never go in front of the ankle-they teach it on personal training courses here in the uk too-and of course it's rubbish, as was my course!
A bit of a tangent - regarding form when performing barbell or dumbell squats: What of knee injuries and the PT tech or the doctor who cautions - regardless of the quadriceps drill, don’t allow the knee flexion angle to pass 90 degrees-a right angle- between the thigh and the shin.
Is the doctor correct to say such a thing?
Just want to know...last thing i'd want to do is try it and blow out the knee[!]
Chris, Sorry it took me so long to answer.
Eh,how are your ACLs? There is minimal tension on ACLs up to 90 degrees knee flexion. The amount of forward knee shift in the squat is not as important as the tracking. For instance, the knee cap (patella) should track over somewhere around the large toe and first interspace. An example of poor knee alignment is posted below in the picture associated with the article, CrossFit & Powerlifting, by Jason Bagwell - May 05 CFJ> Note the knee valgus (knee falling in) on her right knee.
The key issues that are more important are knee tracking, flexibility, appropriate glute max/hamstring coactivation, and position of load. If knee tracking is correct more forward translation of the knee can be tolerated.
By the way, a parallel squat is to 100-110 degrees knee flexion
