At just above sea level, the body makes physiological changes to adapt to the lower concentration of oxygen in the air. The starts at 10,152 feet and maxes out at 12,424 feet, so you鈥檙e right to be concerned about how your body will handle the jump in altitude from your home. Ideally, you鈥檇 arrive as long as you can before race day to allow yourself to acclimatize. Experts estimate that most people fully acclimatize after living at altitude for about .
What does 鈥渇ully acclimatize鈥 mean? 聽There are two big changes your body will undergo, says , a Canadian researcher who spent four months trekking in Nepal to study acclimatization: ventilatory and cardiovascular.
When you rise in altitude, the ventilatory system compensates by adjusting your respiratory rate, and how your breathing is controlled. 鈥淭he breathing system changes much faster than the changes in your blood,鈥 MacNutt says. 鈥淲ithin one to two days at lower altitudes [above 5,000 feet] you鈥檒l be as acclimatized as you鈥檙e going to get.鈥
The cardiovascular system, however, takes about three weeks to fully adjust, depending on how high you go. (The higher you go, the longer it takes.) Within of arriving at altitude, you鈥檒l likely have to urinate often because your body is flushing water from your blood in order to increase the concentration of oxygen-carrying red blood cells. It鈥檒l take for the body to produce more red blood cells and increase plasma levels back to normal鈥攖he effect professional athletes are after when they train at altitude.
One study found that athletes who spent 14 days training at altitude had the and the greatest stamina when racing at about 7,700 feet.
You probably don鈥檛 have several weeks off to hang out in Leadville and acclimatize unless you鈥檙e a pro, but that鈥檚 okay. Macnutt says she found that people who had previously experienced being at altitude seemed to acclimatize quicker when they returned than those who experienced altitude for the first time, though the reason may be more psychological than physiological.
If you can plan a few training weekends at altitude before your race, it may help reduce your chances of experiencing symptoms of altitude sickness, including nausea, headaches, and insomnia. It might also help reduce any anxiety you may have about racing across the sky. 聽