Haha, reminds me of alexkusu, getting the things in the other
way, just that your way is opposit the alex's.
The persons are not nude, bare back means that the horse has no
saddle.
Horses for hippotherapy and carefully chosen and selected (only the
calm horses) and trained not to throw the patients down. They are
supposed not to get agitated easily, preferably not to get agitated
at all.