Iten is a town of a little over 42,000 people on the edge of Kenya's Rift Valley, sitting at roughly 2,400 meters above sea level. It has produced enough Olympic and world champions that locals and visiting journalists alike have nicknamed it the Home of Champions. Nine hundred kilometers north, Addis Ababa spreads across hills between 2,200 and 2,650 meters, with training routes on nearby Mount Entoto climbing past 3,200 meters. Both cities have become fixtures on the calendar of any serious distance runner, and both sit inside the specific elevation band that decades of exercise physiology research keeps pointing back to.
The pattern is easy to observe. What is harder is separating what the science has actually confirmed from what is assumed because Kenyan and Ethiopian runners keep winning. Here is what the published research says, question by question, without straying into advice about what any individual runner should do with it.
