why won't the knees get injured when straightening knees at beginning of deadlift?

[Fleischman]

Carson is referring to stabilizing your knee/hip position by contracting your quadriceps isometrically during the set up.

Set up over mid foot, get a proper grip, bend the knees until the shins touch, set your back neutrally with a big chest, pull. Do all of that without moving the bar forward or backward, and you're golden. The quad contraction comes in immediately after your shins touch the bar.

I meant that your lift comes as you straighten you knees as you push your feet against the floor. The lift doesn't comes as you seek to cantilever your hips down and let your back do the work. If you keep doing what you were doing you will hurt your back.

is this isometric contraction of the quads at the end of the deadlift set up what prevents knee injury when trying to straighten the knees when the lift begins?!

[stef]

is this isometric contraction of the quads at the end of the deadlift set up what prevents knee injury when trying to straighten the knees when the lift begins?!

What are you talking about?

[Fleischman]

What are you talking about?

Straightening of the knees alone causes the weight to start moving off the floor. It is a significantly large amount of force for the knees alone to overcome, and I have been wondering why our knees do not get injured doing that. After reading the comments I quoted I wondered if (somehow) the isometric contraction of the quads prior to starting moving the bar is the reason why the knees do not get injured in moving the weight off the floor. What do you think is the reason?

[Mark Rippetoe]

The knees alone do not ever do anything if you are standing on the ground. Do you have the blue book?

[Fleischman]

The knees alone do not ever do anything if you are standing on the ground. Do you have the blue book?

Yes, 3rd edition, 3rd revision, currently reading through it. My understanding from what I have read so far is that the deadlift cue to push the floor away with the feet means extending/straightening the knees before any hip extension comes into play. What else in addition to knees extension is contributing to lifting the bar off the floor at the very beginning of the lift? Thank you.

[Mark Rippetoe]

My understanding from what I have read so far is that the deadlift cue to push the floor away with the feet means extending/straightening the knees before any hip extension comes into play.

Knees and hips extend simultaneously. You're confusing the cue with the movement triggered by the cue. But why would extending the knees hurt the knees? That's what knees do.

[Fleischman]

Knees and hips extend simultaneously. You're confusing the cue with the movement triggered by the cue. But why would extending the knees hurt the knees? That's what knees do.

Thank you for explaining this. My understanding of the mechanics was wrong. I thought at first it was only the knees moving, then the hips, and not both simultaneously from the beginning. I think it was this video where I got the idea that the knees were on their own for (I thought) like 1/3 or 1/2 of the distance. In re-watching it I see I missed that the hip also starts extending essentially right away.

I now wonder if I also mistook the squat cue for the movement triggered by the squat cue... (drive hips up...)... I have been squatting such that for around the bottom 1/3 to 1/2 of the movement only my hips go up while the back remains at 45 degree to the floor (at which point the back starts going vertical)...

[Mark Rippetoe]

I now wonder if I also mistook the squat cue for the movement triggered by the squat cue... (drive hips up...)... I have been squatting such that for around the bottom 1/3 to 1/2 of the movement only my hips go up while the back remains at 45 degree to the floor (at which point the back starts going vertical)...

If your back remains at 45 degrees, or whatever it is, the hips have also extended.

[Fleischman]

I do not know how, but I see now that my question initiated a new (this) thread, which was not my intention. I meant to reply in the thread in which I found the two quotes I included in my original question about deadlift mechanics.

If your back remains at 45 degrees, or whatever it is, the hips have also extended.

Eureka, I see what you mean! For the back-to-floor angle to remain constant while hips drive upward during the squat, the hips also must extend (otherwise the floor to back angle would decrease as the hips go up!).