No this is the perfect forum for that topic... Yes, there are certainly a good number of indigenous tribal civilizations that used physical endurance as a means to reach altered states in Spirit. The Native Americans did, specifically the Sioux Nation, who did the Sun Dance... which was a three day suspension where the suspended was hooked through his chest muscles and left to hang from them for three days. It was a whole ritual leading up to that... Preparation which included fasting, meditation and a Vision Quest.

As for todays suspensions, I fear for the majority of the time it's merely a fad, but I believe there are some serious participants. Amazingly, when the body is in a state of discomfort the Spirit is free to soar (*note, not saying this is a rule, just pointing out that this does occur) like when one has a fever, the Dreaming is experienced in a far more intense manner than normal. Monks have long used self-inflicted pain as a means of entering higher states of awareness. It's personal and selective, and more importantly, each to his own.