The best ways to prepare would be to go to Colorado as much as three weeks early to acclimate to the altitude, or sleep in a specially designed tent that simulates the thinner air found at higher elevations. Both of these options stimulate your body to produce more oxygen-carrying red-blood cellsbut hey, who's got that kind of time or cash? If you can't increase your body's capacity for carrying oxygen, the next best thing to do is to minimize the negative effects high altitude has on your body. You can do this by:
1. Boosting your aerobic fitness before you go
Since there's less oxygen in the air at 9,000+ feet, you'll be a bit slower and more out of breath. Yet, endurance training gives you the ability to do more work (walk farther, climb faster, etc.) with the oxygen you take in. As a result, greater fitness means that altitude puts less of a dent in your hiking pace. The key is to go for hikes in Missouri, with a loaded pack, at a fast but sustainable pace. You want to be working and breathing hard, but not so hard that you're panting uncontrollably. Hiking at this hard but sustainable pace will increase the amount of oxygen your body can deliver to working musclesat any altitudeand that will help you hike at a steady and comfortable pace in Colorado.
2. Staying hydrated
Dehydration is the number one reason that flatlanders suffer when they go to the mountains. Thinner air is typically drier air, and you lose a lot of fluid very quickly at higher elevations. This is the main reason people get headaches when they go to even moderately high altitudes like Denver (5,280 feet). Running low on fluids diminishes your endurance, contributes to fatigue, and puts you at risk for heat-related illnesses. Start increasing your total daily fluid consumption to between 0.75 and one gallon a day in the weeks leading up to your hike, and then continue drinking plenty of fluids throughout your stay at high altitude.
3. Focus on optimizing sleep
People often have trouble sleeping at higher altitudes, and lack of sleep for a few nights will make your hiking experience far less fun. Staying hydrated will help you sleep better, and so will making sure you have the right equipment to be comfortable. The more you eliminate other factors that could keep you awake, the less chance you have that altitude will cause you sleepless nights. Get a good sleeping pad for your tent and visit an outdoors store to make sure you have the right weight sleeping bag for the conditions. Also consider ear plugs if you're a light sleeper.