exercising at altitude??

i was just wondering what are some of the effects of exercising at a high altitude or just living in a high altitude climate. i read that colorado has the thinest people in america per capita. is this because of the altitude? also how high is a high elevation? there is a mountain by my house that is 4,000 feet high and i was thinking about going to the top every now and then to do some cardio. im trying to slim down. any body in here from denver or does anybody know about how elevation effects the body??

Because the air is thinner it is much more difficult to perform. Many endurance athletes will train at higher altitudes than what the competition is at.

As I understand it, this helps them perform better when oxygen is more abundant. For example, an endurance athlete may get to a 3 mile run in 17 minutes while training at high altitudes. When they come down to lower altitudes it is much easier for them - and they will shave major time off their high altitude time. Resulting in perhaps a 16 minute run time.

The air is thinner up there meaning there is less oxygen. If you stay up there for a week or 2 your body will adapt by generating more Hemoglobin to make up for the missing Oxygen your body needs. Hemoglobin is what carries the oxygen around in your blood. When you come back down to sea-level, you will still have an elevated level of Hemoglobin in your system. That means you'll be pushing more oxygen per breath than other athletes.

The way high level athletes train is to live in a high altitude place and train at sea-level. Becuz training at sea-level will give you the best performance. There's no point in training at altitude and then come down to sealevel to compete at a different pace that you haven't practiced.
There's also a thing called a Hyperbaric chamber. It's just a chamber that can change air pressure. Anyways, they use it for athletes beds. So they sleep their at night so they can benefit from altitude adaptation while living and training at sea-level.

Down side to this is your blood will be thicker, therefore harder to pump through your veins. Of course the benefits out weigh the downside which is evident in performace times. Altitude training is like the legal man's way of blood doping.