Lower Back Injuries
Lower back injuries are a really common issue for strength training individuals. Whilst I'm not a physio and would advise anyone with such injuries to see someone who's qualified (and actually good at their job) I do have a fair bit of experience programming training for people with such injuries, and have suffered multiple disc herniations myself.
Most of this is common sense and should be primarily guided by a good physio however once you've had a serious lower back injury chances are you'll be more likely to suffer another such injury. You can limit the risk of this occurring however by adjusting your training. Below are some suggestions that may be helpful in getting you back to full strength as well as preventing a reoccurrence of such an injury.
*Train your abs. Many strength trainees neglect to perform direct ab work, and whilst I'm not entirely convinced that this type of training directly transfers over to increased strength on the main lifts (but it certainly can in some cases) I am convinced that it can reduce lower back pain. I'd suggest training all abdominal muscles to some extent but with a greater focus on your obliques. My preferred exercises are anti rotation based (such as pavlov press) and side plank variations. For the rectus abs I prefer to stay away from any trunk flexion such as sit ups because I've found it does seem to flare up lower back issues in those who already have such problems (or even had them previously). I highly rate swiss ball variations such as 'stir the pot' and 'saws'.
*Clean up your technique. I did say these were pretty common sense points so there you have it. It can be easy to overlook this aspect though and just repeat the exact same form that ended up getting you injured. If it was a more acute injury where you just got out of position on a certain rep this may apply less however even then focusing on ways of not getting out of position as the weights get heavier will still be useful. For example this could working on maintaining upper back tightness on a squat to reduce the chances of folding forward, or just not overemphasise leaning back and hyperextending your lower back as you lockout a deadlift.
*Stay further away from failure. I'm talking about when you feel back to 100% here. On the big lifts most injuries seem to happen when you go for that final grindy rep of a five rep set and lose position due to fatigue. I love pushing sets hard but there's a time and a place which isn't usually on conventional deadlifts if you've suffered with lower back injuries. That isn't to say you can never push for a max rep set or a true 1RM, rather that the majority of your training probably shouldn't be performed in this manner (a pleasant benefit is that you'll likely gain strength just as fast or even perhaps faster as well if you leave a rep or two in the tank versus taking every set to failure).
*Know your body. Many people have flare ups after a lower back injury. In these cases it usually just feels a bit 'off' rather than painful. The hardest thing for most people who enjoy training hard is to actually back off a bit when this situation arises, it's far easier mentally to just push through it and set out what you came to do especially if it's a heavy session that you've been looking forward to. The key here is knowing whether it's in your best interest to back off a bit or just keep working through it. If your back feels like it's getting stiffer and a little more sore as you progress through your warm ups it's usually best to back off the intensity and work on technique. You could then increase the volume on exercises that don't cause any pain to still get a productive session in.
*Look after yourself. If your hamstrings, hip flexors, and glutes are constantly super tight then chances are your lower back will feel worse than if they weren't so tight. Again common sense stuff but do what you can to reduce any lingering soreness and risk of further injury with massage, mobility, and stretching work. Yes it's extremely boring for most people but if it allows you to train hard it will be worth it.