The following is an exerpt from a research paper I was reviewing for my thesis.
Each subject retired to insert a rectal probe 10 cm beyond the anal sphincter. One subject did not consent to this procedure. Prior to immersion, the level of the tank water was set 2 cm below the level of the gluteal fold in order to accommodate lower limb volume. (Burnley et al 2002)
Ha, ha, this is how I entertain myself, and I'll tell you what...there's definitely more where that came from! One word, Pubmed, knock yourself out :) Okay, I'm sounding lame now. But seriously can we please discuss the lame-o that wouldn't consent to the rectal probe? And let us please give a hollar for "gluteal fold"...ha, ha, I can't say it without laughing.
Burnley, M., Doust, J., H., and Jones, A., M. Effects of prior heavy exercise, prior sprint exercise and passive warming on oxygenn uptake kinetics during heavey exercise in humans. Eur J Appl Physiol 87: 424-432, 2002.