The CXE 2009 expedition followed an identical ascent profile through the Khumbu valley to Everest Base Camp to the ascent taken by subjects on the Caudwell Xtreme Everest expedition in 2007. However, in 2009 the testing was not so laboratory based. Each morning of the trek ascent the trekkers underwent a short period of testing, supervised by the trek leader. In addition, subjects collected data on themselves related to appetite and hydration every day. The studies related in part to new questions that had arisen as a result of our analysis of the 2007 trek data.