So, today I had just about the only trustworthy pt in the LA Fitness I train at check my deadlift at my most recent tested 1rm (335). He said that my lower back caves in a bit when I start the pull.
Now, this week's deadlift session was significantly more challenging than last week's deadlift session. I couldn't get my planned 3 sets of singles today at 345. The moment I initiated the pull, I just felt my lower back give out and I instantly knew following through would be very bad for my back, so I didn't bother. The 335lb went up well last week, but the one I showed the PT today was a struggle. I think my week of poor sleep messed with me? I don't know. Today just didn't go as planned.
Anyways, I've more or less pin-pointed that my lower back is my weak-spot for the deadlift now, besides my weak posterior chain that I am working on with wide-stance squats and a lot of good mornings, and I'm wondering what kind of exercises can I specifically do for my lower back?
I've been trying to do reverse hyperextensions on a bench, but adding weight is a huge pain and I don't think that's a good long-term plan as of now. I'm alternating between rdl and good mornings, but they both tire my hamstrings and glutes out a lot more than my lower back when I try to do them with as good a form as I can manage.
Is there anything more that I can do, or should I just start taking the weight increases on the deadlift more slowly and wait for my lower back to get stronger via the exercises that I am doing right now?