I used to push the AMRAP sets towards 15+ reps too on deadlifts and I agree with those who say that, most likely, when you feel like lockout is sluggish you’re simply gassing or are too fatigued. That’s definitely a big factor.
Other thing is, your lower back rounds at the beginning of every rep. It’s a little butt tuck, happens/happened to me too and I’ve been told it can be dangerous on the long run.
I did the same thing you do on your reps: you lower your hips quickly aiming for a rocking start, but your upper body is not tight enough, so yes, you get the bar moving from the ground but your lower back is getting the brunt of it, rounding.
You feel like you’re pulling yourself in position, and from outside it looks like you’re doing it, but you’re not really doing it, you’re straightening your torso while the barbell is still on the ground and you’re not actually wedged into the bar like you should be, so you lose position when you actually start to generate force.
With those weights, you can crank out rep after rep, but when I got >400lbs pulling that way, the struggle got real.
A user here has linked me Chris Duffin’s deadlift video (see below), which is absolute total gold if you have this issue. Keypoints for the setup are:
-grab the bar in a stiff leg position, then pull it up like if you had to row it, it obviously won’t move from the ground but it will get your upper body tight, you want to mantain this tension at all time;
-big breath and brace, while mantaining tension;
-push your hips towards the bar until your shins meet it. Again: don’t just bend your knees, push the hips towards the bar, and mantain tension;
-engage lats using whatever cue works for you. Duffin talks about locking shoulders down, or you can think about squeezing the armpits, or wrapping the bar around your shins… whatever works for you, while mantaining tension;
this is the video:
at this point you’re ready to pull, and again, Duffin has a simple effective cue - just push your hips forward while mantaining the setup you just achieved.
This will keep the bar glued to your body all the time, while getting your legs to push and your hips to open with the right timing, without having to think about pushing the floor away and when to hinge and so on.
If you’re like me, weaker in the first portion of the pull right off the ground, there will be a second or two when you’ll feel that the bar is just not budging and not moving. Then it will move and you’ll be surprised by how quick and smooth it travels from the floor to lockout.
So, before adding block pulls:
- try to improve your setup and overall technique, tightness especially;
- see how you do in lower rep ranges since your concerns are probably just related to cumulative fatigue during AMRAP sets