Physiological Effects of High Altitude

The air we breath is a mixute of gasses, predominantly Nitrogen (78%) and Oxygen (20.9%). Although the percentages stay the same at high altitudes, lower atmoshperic pressure creates "thin-air."

When your body is exposed to "thin air," it compensates for reduced oxygen levels by increasing the bloods oxygen-carrying capacity, as well as its ability to use that oxygen. Specifically, your body reacts to the thin air at high altitude by:

  • Increasing natural hormone erythropoietin (EPO) production, which in turn increases red blood cell mass for delivering oxygen to muscle cells and converting it into energy.
  • Boosting total blood volume to move oxygen more efficiently through your bloodstream.
  • An increase in V02 max (the maximum amount of oxygen the body can convert to work) giving you more stamina for the long haul.
  • Cranking-up hematocrit levels to provide a greater percentage of cells carrying oxygen.
  • Elevating capillary volume, creating more blood pathways to muscle cells for improved muscle oxygenation.
  • Increasing the volume of mitochondria--the powerhouses in cells that help your body turn oxygen into energy.
  • Increasing the lungs' ability to exchange gases efficiently - so that every breath you take more oxygen gets into the bloodstream.

These changes result in greater aerobic capacity (VO2 max), anaerobic capacity (the body's ability for explosive performance) and improved endurance - meaning faster speeds at a given exertion level.

Studies have shown that athletes who spend an average of eight hours a day at high altitude will experience the same physiological changes as those who spend all their time at thigh altitude. It typically takes at least three weeks for your body to acclimate to high altitude, although improvements will continue for six months or more.