What causes weakness off the floor?
Title says it all. I'm weak off the floor. Why? I have built a very strong and explosive lockout. My top 531 set the other day was 370. I was hoping I could get it about three times, yet I could only do it once and it was like pulling 100%! Here's what happened: Set up(I may have not pulled my back tight enough), lift, and about mid shin I'm stuck pulling to my knees for probably 5+ seconds. Once I get to driving my hips through it's in the blink of an eye and almost without energy. I couldn't believe how hard I had to fight.
So, what causes the weakness off the floor? The last month or so I've been doing deficit deadlifts with about 50-70% of my max for 1-3 reps a set after my regular old deadlifts. I've seen some slight improvement on lighter weights around 300-315. Anything else you all recommend?
For what it's worth, I generally do a deadlift, good morning, ab work one week, and deadlift, deficit deadlift, ab work the next. I also hammer away at my upper back on my bench and press day through the means of pullups, face pulls, and dumbbell rows.