Wilhelm Reich had good advanced ideas about body memory, which got appropriated into the Church of Scientology (and fictionalized) into their "body thetan" concept. People are well-learned in how the sense of smell can bring back up and back memories from ages earlier.. but they oddly don't think how certain touches can do the same. Body memory is the *last* to go.. hence those jokes about "sorta like riding a bike" for one or "forgetting how to walk". So anyway.. yoga stances often work muscles that aren't used in normal activity, and require precisely moving oneself to poses that set off the deeply-implanted "No, that leaves me vulnerable" physical and emotional reactions. So does BDSM.. and in both a person can realize they may hurt there, but its in a safe place, they are not being used by a bully in this circumstance, or under life-threatening attack. Essentially that cleans up the body memories quite a bit, cause those odd old memories will come up during the session, and be released. YMMV.