High Altitude

Doing physical work at high altitude presents enormous challenges, whether a person climbed to get there or was taken there as a member of a search crew. High altitudes are likely to be cold, often to the extreme, and the terrain is sufficiently harsh that the human system is under constant strain to do physical work. Moving quickly from lower to higher altitude (as often occurs when athletes who live at sea level train at high altitude to enhance oxygen-carrying capacity) may result in headache and nausea, both of which can negatively influence food and fluid consumption. The lower oxygen level of high-altitude air makes fatigue come early, and the difficulty of eating and drinking normally may lead to enough tissue loss that cold tolerance is decreased. Maintaining body fluid balance in extreme cold is just as difficult as maintaining fluid balance in hot and humid environments, with increased urinary flow and voluntary dehydration both contributing to the problem of taking in sufficient fluids to avoid dehydration. Simply preventing drinking fluids from freezing presents a challenge, and cooking takes much longer at higher altitudes than at lower altitudes (so more fuel must be transported). The challenges of performing physical work at high altitude are daunting, but nutrition strategies can help people attain their goals in this environment, whether it's a 3-day 14,400-foot (4,390 meter) climb up Mount Rainier or a week-long trek up the 19,340-foot (5,890 meter) Mount Kilimanjaro. This chapter reviews the physiological and nutritional stresses the human body experiences when working in the often cold setting of a high altitude and presents recommendations for successfully dealing with this environment.

High-Altitude Training

Meeting Energy and Nutrient Needs

Meeting Fluid Needs