ABSTRACT
This chapter considers the issue of acclimatization in greater detail. The transient phenomenon of acclimatization must be distinguished from the concept of adaptation, which refers to characteristics present in long-term high altitude residents that have arisen as a result of natural selection working on the gene pool. These characteristics serve to distinguish people born and bred at high altitude from even well-acclimatized lowlanders. While most people can acclimatize to moderate to high altitudes and do well when adhering to published guidelines, it is important to remember that there is significant inter individual variability in the pace of acclimatization and susceptibility to altitude illness. In the absence of dehydration and physical exhaustion, high altitude deterioration is characterized by weight loss, poor appetite, slow recovery from fatigue, lethargy, irritability, and an increasing lack of willpower to start new tasks. There is impaired cognitive function and dulling of affect and, in some cases, low systemic blood pressure.
