Six months ago I badly ruptured my L5 S1 disk. I had really bad sciatica, my left foot went numb and I loss the use of my left calf muscle. I opted not to have surgery and had months of physical therapy instead. Now, six months later, I feel almost close to normal. My calf is working again, the numbness is gone and I'm left with just some mild pain and stiffness.
To get back into cardio, I did the following (under the supervision of my physical therapist):
Walking on flat surfaces, on a treadmill or outside (no hills, however)
Recumbant bike riding
Elliptical
I started out doing just 15 minutes a session and then added 5 minutes on at a time. I'm now back to doing full blown Cardio Coach on my recumbant bike and elliptical. I can also do almost any type of low impact exercise (although kickboxing still gives me some trouble). Low impact step aerobics is okay, but I haven't really tried it much yet.
The bad news is that high impact is out for me, so the IMAXes are now just a memory. I was told I could attempt some high impact, but that since I had a bad back injury, I will always be at greater risk for another one. For me, doing high impact is not at all worth having a recurrence of the pain. I was very bummed at first but have come to accept it and be grateful that there are still plenty of things I can do (such as Cardio Coach). I can also lift weights, although I've had to drop down in weight. I sadly cancelled my STS order, but I found Jari Love instead. I still do a lot of Cathe weight workouts, but I've learned the moves I need to modify or avoid altogether.
I would say you should consult a physical therapist or a doctor to discuss any limitations you might have. Trust me on this one, you don't want that disk to rupture. I started out with "disk space narrowing" a few years ago but I didn't limit anything I did and I ended up with this crap injury. I know six weeks feels like a long recovery, but if you mess up your back even further it could set you back for months. I have to admit that my doctors weren't overly helpful in terms of getting me back into exercise. PT was what saved me. They really helped me find ways to stay fit with a bad back. They taught me all the essential stretches and strengthening exercises that help a bad back.
Good luck. I hope you are able to return to more normal activities very soon.
Shelbygirl