Deadlift and squat plateau

 I've been on a plateau for my deadlift and squat. The problem is I keep bending over at the waist. When this happens, my lower back is overused and since I don't wear a training belt to support my lower back I consequently don't make the lift. What do I do now?

I guess I have to listen to this guy. He squats about half a ton give or take a couple hundred pounds. In this video he gives some complementary exercises to address weaknesses. Notice how he recommends seated good mornings and some weird lower back machine that probably doesn't exist in 90 percent of all commercial gyms.

I used to do stiff legged deadlifts and I saw pretty good gains in my deadlift. I think the reason was that the form for the stiff legged deadlift has you start in a bent over at the waist position with knees almost locked straight and deadlifting the weight off the ground. This motion will pretty much blast your lower back and hamstrings.  Be careful though as this puts your lower back and hamstrings in a position very susceptible to injury. 

The amount of tension you can hold in your hamstrings determines how well you keep your upper body locked in an upright position. If you lose the tension in your hamstrings, you'll double over at the waist and use  the lower back to make the lift which is a good way to injure your lower back.

I think the guy in video above talks about hamstring tension somewhere in his video series. It's a five part video series and you should definitely watch it.