I had a rapid weight gain due to taking anti-depressant called nardil...an MAOI. I went from 190 to 232 in 5 mos. The doctor told me to walk or jog at least three times a week to control the weight. I did this and my back began to hurt until in 18 mos. my left leg collapsed from under me. The pain then became permanent in my back near my third vertabrae. I stayed off my feet mostly for eight mos. and found that I could play tennis come spring, though there was more moderate pain in my lower back...that did not pass down thru my leg as it had. Now tennis season is over and the back still hurts. Walking any distance quickly still makes it hurt more. Doctors could find nothing in the tests performed. I blame this on doctors prescibing walking and jogging for overweight people. Machines that exercise all body muscles, I think, was the proper exercise, instead of banging my feet against the sidewalk. I never had a problem back before my doctor prescibed that daily regimen. Also, the same doctor missed my diabeties when I complained about numbness in my toes and fingers. So much for alot of the HMO docs.