I've been running riders for more than a year now and am having some back problems. Specifically with posture because I look to be an ich or two shorter. It seems like I was fine until I started using my phazer I got in sept. 07 and now my lazer z I got this year. Can running a z for a long time cause back trouble or cause your back to get out of alinement? Is a w/b or stander better? I have owned a used stander before but didn't like standing for a long period of time. But is it better to stand than to sit for your back?