ABSTRACT
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 564 Nutritional Needs during High-Altitude Sojourns . . . . . . . . . . . . . . . . . . . . 564
The Hypoxic Environment and the Oxygen Transport “Cascade” . . . . . 564 Physiological Adjustments to Exercise at High Altitude . . . . . . . . . . . . 566
Respiratory Exchange . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 566 Systemic O2 Transport . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 567 Energy Metabolism-The Lactate Paradox . . . . . . . . . . . . . . . . . . 568 Work Capacity and Physical Performance . . . . . . . . . . . . . . . . . . . 569
Nutrition during Sojourns at High Altitude . . . . . . . . . . . . . . . . . . . . . 570 High-Altitude Weight Loss: Energy and Water Balance . . . . . . . . . 570 Macronutrient Requirements at High Altitude . . . . . . . . . . . . . . . . 572 Micronutrient Requirements at High Altitude . . . . . . . . . . . . . . . . 573
Nutritional Needs in Hot and Cold Environments . . . . . . . . . . . . . . . . . . . . 573 Regulation of Thermal Balance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 573
Biophysics of Heat Exchange Between Humans and Environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 573 Human Thermoregulatory Control System . . . . . . . . . . . . . . . . . . 574
Cold Stress . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 575 Physiological Responses During Cold Exposure . . . . . . . . . . . . . . 575 Factors Modifying Physiological Responses to Cold. . . . . . . . . . . 576 Impact of Cold Exposure on Nutritional Requirements. . . . . . . . . . 578
Heat Stress . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 580
Physiological Responses to Heat Stress . . . . . . . . . . . . . . . . . . . . . 580 Factors Modifying Physiological Responses to Heat Stress . . . . . . 582 Impact of Heat Stress on Nutritional Requirements . . . . . . . . . . . . 583
Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 585 Disclaimer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 586
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 586
Millions of people live, work, and play in regions of the world where weather is intemperate or at terrestrial elevations where ambient oxygen pressure is less than at sea level. Exposure to extremes of heat, cold, or hypobaric hypoxia can elicit a variety of physiological responses in humans, which assist the body to re-establish and/or maintain homeostasis under the influence of new environmental conditions. Those physiological responses can have nutritional implications.
