In '05 I was diagnosed with spondylolisthesis. Physical Therapy was prescribed. I wasn't riding regularly at the time. I asked my PT about cycling and she said it was "contraindicated" for my condition. Indeed, when I rode I could feel it in my lower back. After PT I continued the PT exercises and walking for exercise. Gave up on riding.

At the same time I was trying to lose weight. My problem is I am on the See Food diet. I see food, I eat it. I created spreadsheets trying to calculate my way out of my predicament. But walking just wasn't burning enough calories.

In Aug '08 my pickup battery died. My family was busy, so I dusted off the bike, aired up the tires and took care of my pickup. That night filling out my spreadsheet, using calorie estimates from the web, I discovered one hour of riding around at a slow speed was more than twice one hour of walking in calories. And my back felt fine.

Work was only 2 1/2 miles from home. I started commuting. Telling myself it was OK to quit if it was too hard. Within a month I was riding 3 or 4 miles during lunch. Then riding 8 miles before getting home. Within six months I had lost 30-35 lbs! And my back felt better!

I'm still giving the PT exercises for stopping the back pain. In fact if I stop those exercises for more than 2 weeks the pain comes back. But the bicycling doesn't bother my back. And keeping the weight down has to help.

Just my experience. Good luck to those working on their back problems.