I think the problem solution lies somewhere else. If you watch some Eastern Bloc deadlift kings, where do they miss their pulls? During lockout? Nope, never. If you watch carefully, if the weight is too heavy, it is missed right off the floor or before the bar reaches the knees. Never during lockout. Why? Because lower back is not responsible for lockouts, it is the glutes. Yes, the most powerful muscles you have. Powerful hip thrust using your glutes is what lockouts your deadlift.
Watch below some of the best Russian pullers how powerfully they lockout their pulls.
Pozdeev: powerful hip extension at lockout
Malanichev: powerful hip extension at lockout
Belyaev: powerful hip extension at lockout (side view)
If you miss your pull at lockout, it is not your lower back but weak glutes. Remember, you lower back does not move thoughout the pull, it stays fucking rigid. Lower back can feel tender the next day after pulling but it never should be sore. If your lower back aches the next day, you are pulling wrong, period. The extension should be in hips, not lower back. The day after heavy deadlifting you should be sore in glutes, hams, hips and lats because they contract so hard keeping the bar close to the body.
How can you get strong and powerful glutes? In my book, it is using these three lifts:
1/ deep and heavy front squats. They hit you quads, glutes, hips, abs. All around an awesome lift. Go heavy. 5 sets of 5 or 6 sets of 3 should drive you to the ground. Go fucking heavy. Your front squat should be around 70-80% of your back squat. If you can back squat 250k for 5 reps, you 5 reps on front squats should be with 180k - 200k.
2/ medium heavy high-volume sumo pulls. After a few sets, your glutes, upper hams and hips should be on fire. Go for 5 sets of 5 or 6 sets of 3 or fucking whatever. If you are nuts go 6 sets of 3 with 70-80% and finish with 2 sets of 15 with lighter weights. Don't hate me the next day.
3/ Romanian deadlifts. Heavy sets of 5 or 2 sets of 20 with 50%. Try it, it is no picnic. The 2 sets of 20 should leave your hams and butt sore for days.
Now pull something heavy and hump the bar at lockout, your lower back will thank you ;-)
