Hypoxia (Hypoxic Training)

  
This is the term that means low oxygen content.  Hypoxic Training refers to a method of training in which athletes train while restricting their breathing.  The idea is similar to that of elevation training, which conditions the body and muscle groups to operate with the use of less oxygen.  

This method of training is the cardiovascular equivalent of swim training with a drag suit.  The body acclimates itself to its conditions and can reap benefits if it overcompensates for resistance and/or the lack of oxygen during training.

What happens (in simple terms) in hypoxic training, is that the blood and muscles are forced to develop the ability to absorb oxygen more efficiently in order to perform rigorous activity.  When the athlete goes to compete, his or her capacity to efficiently utilize the oxygen will be greater than those athletes that didn't develop increased oxygen capacity.  This should equate to better performances.

Hypoxic training, however, is not very comfortable.  Especially since it runs contrary to our sense of survival.  We need to breath to survive!  As a result, many athletes hate this type of training.  However, athletes that have altitude trained have reaped the benefits time and time again.  Using hypoxic techniques, within reason, should provide similar results.  As we always say, every 100th of a second counts, and as long as it can't hurt your performance, it is worth a try.  In this case, the benefits are proven--so give it a go!

Note: when breath holding techniques are practiced during exercise, there is a large increase in the desire to breath.  This in not due to hypoxia, it is due to an increasing concentration of carbon dioxide within the blood, which triggers the breathing reflex muscles.  The hypoxia merely refers to the lack of oxygen being introduced into the body, it is not what causes the body to want to breath.  That is from the CO2 buildup.  Do not go nuts with this type of training, and always try to practice this under the supervision of someone who is familiar with this technique and can monitor you as you perform.