Investigating hormonal adaptations to high altitude: five years of Defence Medical Services expeditions.

The military has a tradition of supporting and promoting scientific expeditions. The past five years have witnessed a series of Defence Medical Service (DMS) expeditions to mountainous areas of the world, which set out with the dual purpose of researching high altitude human physiology and promoting the uptake of adventurous pursuits within the military. Beginning with exercise Medical Sentinel to Aconcagua, Argentina, in 2007, members of the DMS have since conducted two expeditions to the Himalayas (expedition Imja Tse, 2009 and expedition Khumbu Ramble, 2011) before returning to South America, to the Cordillera Real mountain range in Bolivia, on expedition Bolivian Venture, in late May 2012. This article aims to provide a brief background to the rationale behind these expeditions, a brief description of our understanding of altitude sickness and a history of the adventures that members of the Defence Medical Services have been having contributing to that understanding.