INTRODUCTION

Of all the ecozones in the tropics, one of the most challenging in terms of its effects on physical work capacity is found in the high altitude mountains. Not only does one have to contend with many of the health and nutritional problems associated with underdevelopment but one also has to adjust to the reduced atmospheric pressure and partial pressure of oxygen associated with high elevations. Since oxygen is required for all aerobic work, a reduction in oxygen tension will reduce aerobic work capacity unless substantial adaptations occur in systemic oxygen transport and utilisation.

Considering that all of the tropical high altitude populations also reside in less developed and economically poor countries, it is very likely that many environmental stressors act in concert to reduce the physical performance of these indigenous populations. Most previous studies of work capacity in high altitude natives of the South American Andes suggest that the maximum aerobic capacities are comparable to indigenous low altitude groups engaged in similar types of physical activities (Buskirk, 1978). This suggests that Andean natives have adapted to the stresses of hypobaric hypoxia to a large extent through improved oxygen transport and utilisation. This may be true for the samples studied. However, if one examines the physical characteristics of weight and height for these highland samples, there is some question as to how representative they are of the general population of highland natives.