I drew this deadlift diagram during the noon class yesterday and posted it to the Members Only Facebook Forum (if you don’t know what that is click here). I figured everyone could benefit from it along with some tips.
Deadlifts (and pretty much every other lift) MUST be performed with an isometrically contracted, flat back. If your back (from tail to neck) during the lift does not remotely resemble that of a healthy person in an upright position with their chest up and shoulders down and back then YOU must do something about that. Put bumper plates underneath your barbell such that you can flatten your back in the bottom position and start working on your posterior chain flexibility, like, yesterday.
Bottom position (left figure):
Notice that the knees and shoulders are in front of the plane of the barbell, the chest is over the bar, and the hips are well above parallel. The barbell itself is on the body, touching the shins. Weight is distributed across the entire foot, making points of contact with the floor in the heel and balls of the foot. There should also be pressure across the arch.
Once in this position, imagine a triangle (in red) connected between the shoulders, hips, and the barbell itself. As you begin to stand up with the weight, imagine each corner of this triangle rising at the exact same rate (red vertical arrows). In order to do this, simply draw the knees back (blue horizontal arrow) to keep the barbell following a straight path along the body.
Another way to think about this is that the angle created by the back with respect to the floor (green dotted lines) should not change as the weight is passes from the floor to the knee.
Halfway point (right figure):
As the weight ascends to the knee, the shape of that imaginary triangle should not change. This can be seen in both figures as well as with an identical back angle with respect to the floor. This is most challenging phase of the upward part of the lift from a technical standpoint since once the barbell passes the knees you just stand up.
Coming back down, simply reverse the process!
The most challenging parts flip though because as you descend you must drive the hips straight back, keeping your knees directly over your heels in order to keep them out of the way of the incoming barbell. In this diagram, imagine that horizontal blue arrow from the left figure now placed at the hip of the right figure still pointing to the right.
Once the barbell gets to the knees as seen in the right figure, imagine flipping the red vertical arrows in the left figure to point straight down. This part is easy because you literally let gravity drop you to the floor as you punch your knees back over the barbell.
And now you’re back EXACTLY where you started. Right? RIGHT!