I had an xray on my lower back about 5 years ago and was told there is slight wear and tear, now when I do any exercise which involves bending and stretching it gives me jip for the rest of the day, for example yesterday I spring cleaned my kitchen cuboards top and bottom, but then when I walk and I walk on average 4 miles a day and at a pretty fast pace, it seems to ease and I dont get hardly any pain, infact walking seems to help.
At one time, hospitals used bed rest and enforced immobility to treat some lower back problems. They realised this was not altogether useful...now the same conditions warrant physiotherapy and frequent exercise!
I've had lower back pain for quite some time, apparently wear and tear and arthritis, and the physio I've been seeing has suggested trying Pilates, I haven't tried it yet, but certainly intend to in the near future - have you considered that, fruitsalad?