I destroyed my back doing this for mitch, but thanks to the wonderful-for-bad-backs clamshell chairs I brought up in August, this time was SO much easier on the body.
I recommend them for anyone with a bad back. Its like fingers in perfect gloves for the old lumbar when you work/relax in these.
Man they do good work at Graniels. http://AmbergrisCaye.com/graniels/