This was my first workout after hurting my lower back on Sunday and I'm still in pain. I wanted to test things out, very slowly, and do some movements like pullups that would not bear on my lower back and could still give me a challenge at a controlled, non-kipping, manner. I did use the weight belt for weighted pullups but progressed slowly and when I felt any pain in the back as I leaned back to go over the bar, I would either slow down even more or stop, or reduce the reps, etc.
10 x bodyweight (felt fine)
weighted 10 lb x 10 (felt fine)
20 lbs x 10 (felt good - but grip was feeling it a bit)
25 lbs x 8
30 x 7
35 x 5 (felt a twinge as I was going over the top at the last couple reps)
35 x 5 (same)
35 x 5 + 5 at bodyweight... FULL ROM slowly contracting all reps.

Post pullups went directly into the pool quickly and basically did laps for about 15 minutes of breast stroke and freestyle... the freestyle felt it a bit in the back as I rotated, but it was o.k. and I felt like I was loosening things up a bit with no weight and some ROM in different planes.
I did a bit of stretching in the Sauna and a hot shower... FELT MUCH BETTER after all that.