MentalRuler did not say what type back injury he was dealing with. Disk, ligament, tendon, muscle strain, pulled, etc. Is the back getting better or worse? Is he under medical care? If he has reached the age where moderation is the general training rule, than that's what it should be. Try to train around an injured back, if you can. Lighter weight and no sudden moves, like cleans, Hi-pulls, etc. You can still get in productive workouts, with a little planning and caution (GVT comes to mind, where even a moderate weight give an outstanding workout). Hyper extensions/GoodMornings will strengthen the muscles around the lower back. But if a ruptured disk or any ligament problems, direct exercise should be avoided until back is somewhat normal. That may take time. Sport and deep tissue massages can help also, as can light stretching exercises.
I had a major operation on my #4 & #5 disk while in college. I'm lifting more than ever before at the age of 34 but I do have my bad day's on occasion. Took a little less than a year to get back into somewhat normal shape ater that operation.
If you have any back trouble doing any overhead lifts, you might try placing one foot ahead of the other and have a slight bend to both knees. Reduces stress on the lower back. Sitting, while overhead pressing, may not be the best idea for some. Too much direct pressure on that lower back from the mechanics/leverage of that position. Just trying to hold the lower back in a stable position, while pressing overhead, may cause undo tension. Good luck.