Here's more from Mark on the deadlift:
"I like overanalysis, but I think you have missed the main point. There are 3 criteria for the correct deadlift position off the floor: The bar must be over the mid-foot, the back must be in extension, and the scapulas must be over the bar.
The primary concern for all barbell exercises where the bar is held on the body or in the hands is that for the system to be in balance with heavy weight the bar will be directly over the middle of the foot. In the deadlift, this occurs at the starting position when the bar is touching the shins with the knees slightly forward of the bar. But the knees are not the marker, the mid-foot is.
The fact that the back must be in extension is rather obvious. But the scapular position is not. The spine transmits the force generated by the hips and legs up to the load, the traps hang the scapulae from the spine, the arms hang from the scapulae, and the bar hangs from the arms. The scapulae are the bony components that receive the force from the back, and they are the points below which the bar hangs. In this position the arms hang at a slight angle back to the bar when the arms are loaded, and the lats keep them there so that the bar can stay under the scapulae. This position is identified by the arm angle, 5-10 degrees in most people -- it is not necessary to see the scapulas to know they are in the right place if the arm angle is correct. Vertical arms are not correct.
When you see videos of lifters in their set position with the arms vertical or even behind the vertical, play the video frame-by-frame until the bar breaks the floor. If the weight is heavy (light weights can be done wrong) you will see the configuration described above establish itself. The back angle that you see as the scapulas settle into position over the bar is the correct angle, and will vary with the lifter. My point is that an incorrect start position wastes juice, because the correct position will be along shortly whether you want it to be or not.
Find me a heavy deadlift that does not conform to this model and we'll talk. Magnusson's and Bolton's records both do, but watch them carefully to see this. The weight is so heavy that their upper backs are rounded by the load, making the arms relatively vertical -- possible because of the fact that the bar is still directly under the scapulas. In both cases the bar is directly over the mid-foot. There will be examples of bad form, but my point is that from a musculoskeletal perspective, there is only one efficient way to pull the bar off the ground, and any other configuration wastes energy trying to get it back in balance that could otherwise be used to pull more weight.
When we teach the deadlift, we place the feet under the bar with the mid-foot directly under the bar, we take a grip right outside the legs, we lower the butt until the shins come just into contact with the bar but DOES NOT CHANGE ITS POSITION ON THE GROUND, lift the chest (placing the back in extension) and pull the bar up the legs. This results in a correct back angle and a correct pull every time, provided hamstring flexibility is sufficient to pull the back into good extension in this position. It feels funny at light weights because of the differences in center of mas distribution, but everybody reports that as the weight gets heavier it feels better than any other form they've tried to use."