Why do athletes train at high altitudes?

At high altitudes (e.g. on the top of a mountain), the air is ‘thin’ and the oxygen content is much lower.  So in order to make up for this reduced level of oxygen, the body manufactures more red blood cells.  This is what athletes want-so that when they compete and return to ‘normal’ altitudes, their blood is still adapted to ‘thin air’ with many more red blood cells than normal-and therefore more oxygen is available to the muscles.

What is ‘thin’ air?

As the human body travels up in altitude, it is exposed to a state of hypoxia (low oxygen).  The actual percentage of oxygen in the air doesn’t change, but the barometric pressure decreases, and this in-turn decreases the amount of oxygen that can be extracted during respiration.  This is what is meant by ‘thin-air’ at altitude.  

Concerns

Hypoxia results in two main concerns for a training distance runner;

• a decreased maximal oxygen consumption and,
• the kidneys give out an increase in enthropoietin (protein hormone given out when the oxygen concentration is low).

Longer term changes of high altitude training

1. A decrease in maximum cardiac output, a decreased maximum heart rate
2. An increased number of red blood cells
3. Excretion of base via the kidneys to restore acid-base balance (this results in a lower tolerance for lactic acid)
4. A chemical change within the red blood cells that makes them more efficient at unloading oxygen to the tissues
5. An increase in the number of mitochondria and oxidative enzymes.

                                                                                 RED BONE

KIDNEYS                                                                  MARROW

LOW TENSION

STIMULATES

                   TISSUE ORGAN                                  RED BLOOD CELLS

                                   INCREASED NUMBERS RAISE

                                  OXYGEN CARRYING CAPACITY