I have severe post concussion syndrome & had a ruptured disc 3 months ago that was so severe I couldn't feel my legs but I did mine train three times within 30 min this week without a problem... Everest I tried, kind of hated while on it (tipping feelings, vibrations, disorienting), had to sit quietly when got off and was not at all comfortable riding again (so I sent my 8 year old on as a single rider over and over)... I have no interest in ever riding again, but if for some reason I wanted to (with a child I didn't trust to send alone or if I felt I needed to with a friend or family member, I could do it and be ok, just not at all fun... if that helps...