Training at altitude has been used to improve athletic performance for decades. Following the Olympic Games in Mexico City, numerous American running records fell, and soon after researchers discovered that altitude was the reason. Since that time, many teams and individuals have used altitude training as part of their preparation.
Exposure to reduced oxygen levels (altitude or hypoxia) is a challenge to the human body because oxygen is the primary source of energy for our cells. Under a state of hypoxia the body strives to produce required amounts of energy with less oxygen available. To do so, a protein called Hypoxia Inducible Factor (HIF-1) sets off a host of reactions geared toward improving the body’s ability to utilize oxygen.
There are 3 main training methods used to gain the benefits of Altitude Training: Sleeping at altitude, Exercising at altitude, and Intermittent Hypoxic Training. Here is a fantastic overview of the different training methods and the performance enhancements of each method.
Nick Grantham on: Methods and Explanations of Altitude Training