The human body is an extraordinary machine, an unending source of wonder. In order to unlock its mysteries, scientists sometimes go out of this world. In 2001 and 2002, Dr. Douglas Watt of McGill University in Montreal studied how the human body adapts to weightlessness through his H-Reflex experiment. H-reflex was the first medical experiment completed on the International Space Station.
http://www.space.gc.ca/asc/eng/sciences/canada_hreflex.asp