As coincidence would have it, I just posted a blog that deals with a somewhat similar situation, I think. Please read it if you have time.
In regards to your question… I’ve read all of the responses you’ve gotten so far, and I don’t see anything that could be added without knowing more specifics about the situation. I think Karin offered some excellent advice, all around. I especially agree with what she says about machines.
The only thing that I would like to bring to the table here is… If you know someone with bulging disks, perhaps you should consider telling this person about inversion therapy? I like to consult the LIVESTRONG foundation on a variety of different topics. Here is what they have to say about it.
I strongly urge you to check out this article. Also check out the resource links at the bottom of the article to get further information on the topic. Like Joanne has said before, you can’t give away what you don’t own. Own the knowledge about this condition, and you’ll probably find yourself giving quality services to those who suffer from it. (if they’re cleared by a physician to exercise)