According to Protestants, is it sinful to practice Yoga?

I know a lot of people who claim to be Christian but practice Yoga. I always thought (and [Wikipedia](http://en.wikipedia.org/wiki/Yoga) seems to back me up on this) that Yoga was about meditation in Hinduism or Buddhism. Is practicing Yoga a sin since you're actually following another religion? Or is it possible to practice Yoga in a Christian manner? Also, if you are able to practice Yoga in a Christian manner, is there a conflict with that and the problem with [the weaker brother](http://www.biblegateway.com/passage/?search=1%20Corinthians%208:9-12&version=NIV) ? Specifically, I'm seeking a [mainstream Protestant](http://en.wikipedia.org/wiki/Mainline_Protestant) viewpoint on this. I suspect that they will all be the same, but if they differ, let me know so that I can refine the scope.