This research will help us provide you with the facts about running at altitude (physiology, adaptation, training). Summary: At altitudes above 5,000 feet, running becomes more difficult, and performance capacity begins to decline markedly. However, training at high altitudes for as few as three weeks will enable runners to gradually improve their performance capacities at such heights. In addition, while altitude training has been shown to improve the body's ability to transport and process oxygen, this does not necessarily mean that sea level racing performance will be enhanced. One of the reasons for this is that, at high altitudes, one cannot train at speeds that approximate sea level race pace. There are also many potential complications associated with altitude training - from dehydration and insomnia to headaches and blood pressure instability. Still, many world-class coaches have successfully incorporated altitude training into their overall training programs. These coaches break altitude training into adaptation phases in order to derive maximum benefits and avoid the complications that come with overstressing the body's system. These same coaches report that peak performances occur at sea level 10 to 40 days after completing the high altitude phase of their training programs. While there is no scientific evidence that high altitude training can improve sea level performance, many experts still believe you can use altitude training to lift your performances to new and higher heights!