Changes

Training at high altitude has been shown to improve endurance. And high-altitude there is less oxygen available, and this forces adaptations such as increased red blood count and improved [[Muscle|muscle ]] metabolism that help with endurance both at altitude and at sea level. Initial [[Altitude Training Approaches]] involved living at a high altitude location for some time, and this approach is still used by many of the athletes. However, this is expensive and impractical for many people, so various altitude simulation approaches have been developed. Most of these approaches reduce the oxygen content of normal pressure air at low altitude.