JEPonline Physiological Responses to Altitude: A Brief Review

Wyatt, FB. Physiological Responses to Altitude: A Brief Review. JEPonline 2014;17(1):90-96. Hypoxia has been defined as conditions with lower than normal oxygen availability. Altitude exposure and acclimatization have been areas of research for a considerable time. The immediate (acute) effects of lowered ambient pressure of oxygen (PO2) pertaining to the human response and the adaptations to prolonged exposure (chronic) are complex. Several systems (i.e., cardiovascular, pulmonary, and endocrine) react to the hypoxia associated with altitude exposure. Adding to the complexity, these systems rarely react in isolation but rather interact to allow the work of the individual to be accomplished in this type of environment. While generalities exist relating to acute and chronic adaptations (acclimatization) to altitude exposure, current evidence indicates individual responses may facilitate or hinder the acclimatization process. Responders and non-responders have been identified in the literature during attempts to understand the human response to a lowered partial pressure of oxygen. This review summarizes the affects of acute and chronic exposure to altitude as it relates to exercise and work output. Several sub-categories will be addressed. Included in these categories are the following: (a) acute and chronic exposure; (b) performance and length of events; (c) substrate utilization; and (d) various adaptations associated with various increasing altitudes. While much research has been conducted regarding living high/training low (LHTL) scenarios, this review will only discuss findings associated with acute and chronic exposure to altitude. Thus, the purpose of this brief review is to summarize two basic tenets of altitude and exercise: (a) acute exposure response; and (b) chronic adaptations.