ADAPTATION TO I liTUDE 



tional characteristics among people 

 who can be identified as: (a) high- 

 landers for many generations; (b) 

 lowlanders acclimatized to altitude; 

 (c) new arrivals at altitude; (d) high- 

 landers acclimatized to sea level; and 

 (e) lowlanders. 



It is not clear what these differences 

 mean. We do not know, for example, 

 whether these differences reflect sim- 

 ple adaptations to a new environment 

 or are the result of selective adaptive 

 processes or even, in some instances, 

 are detrimental to the individual. 



For the people who now live at 

 high altitude, and for those who will 

 move there, the most important area 

 of altitude physiology is that which 

 has to do with natural and acquired 

 acclimatization. Study of these proc- 

 esses should direct particular atten- 

 tion to the functional adaptation of 

 people of both sexes, of all ages, and 

 of those living under different work- 

 ing conditions. 



Of lesser importance to human 

 populations as a whole is the study 

 of the acute adaptive mechanisms, 

 which are of concern to the much 

 smaller groups of people moving be- 

 tween high and low altitude and for 

 whom residence at high altitude is 

 usually brief. 



Physiology of Exercise and Work 

 Capacity at Altitude — A number of 

 human populations at various levels 

 of altitude have for many generations 

 lived and worked while exposed to 

 low levels of ambient oxygen content, 

 although they have not necessarily 

 been exposed to continued tissue 

 hypoxia. The physical performance 

 capacity of these populations is not 

 adequately established. 



Studies were suggested on: the 

 basic work capacity of highlanders; 

 the maximum oxygen consumption of 

 altitude populations; the metabolic 

 response to work in various high- 

 lander populations (see Figure XI-5); 

 the effect of age and sex on work 

 capacity in altitude populations; the 

 relationship between heart rate and 



oxygen consumption in indigenous 

 highlanders. 



Altitude Limits for Acclimatiza- 

 tion — There is a need to specify 

 altitude tolerance limits for human 

 and other animal species. The tem- 

 poral maintenance of normal func- 

 tional integrity of organ systems, be- 

 havioral activity, and physical and 

 mental performance should be eval- 

 uated. 



Environmental Factors - 

 are needed to determine the si 

 cance of environmental factors other 

 than hypoxia in altitude acclimatiza- 

 tion such as the climatic conditions 

 and the socio-economic environment. 



Respiration — An important adap- 

 tation of the resident to altitude, 

 which is different from the lowlander, 

 is his pulmonary ventilatory response 

 to different concentrations of both 



Figure XI-5 — OXYGEN CONSUMPTION CAPACITY AMONG 

 HIGH-ALTITUDE NATIVES 



The maximum oxygen consumption capacity of native highlanders at high altitudes 

 is comparable to that of native lowlanders at low altitudes (see Figure XI— 4). Thus, 

 the work capacity of the two groups is similar in their native habitats, although 

 lowlanders are at a disadvantage when they migrate to high levels. 



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