I wish I could be of more help, but I've only used mine a few times (I'm traveling most of the time). I can tell you it worked the HECK out of my muscles and I was SORE! So it has to work good, but I haven't had a period where I've been on it more than twice in a row.
I'll get on it all week next week (I'm home all week) and I'll report back to you!
It's an evil torture rack that masquerades as a dancer's barre that you follow the dvd's to get a lean dancers body. I'd LOVE to have something small and portable to really get into it because it works muscles I didn't know I had.
If you want to check it out biki, it's wubba wubba wubba dot fluidity dot com