Northern Arizona University

The Effect of Altitude

As you ascend to altitudes above about 1000 meters (a little over 3000 feet), the amount of oxygen that is carried by the hemoglobin in the blood is reduced, resulting in less oxygen being delivered to exercising muscles.  In endurance sporting events that rely on the availability of large amounts of oxygen, a decrease in delivery results in below-normal performance.  However, this is true only in low-speed endurance events, such as running, swimming, paddling and rowing.  In high speed endurance events, such as speed skating and cycling, the lessened air resistance experienced at altitude is more beneficial than is the loss of aerobic power and performance is actually better at moderate altitude.  With time spent training at altitude, the body makes some adjustments and performance at altitude will improve over a period of several weeks. But regardless of the time spent at altitude, sea-level performances in slow-speed endurance events will never be matched at altitude.  In fact, if previous sea-level times are matched at altitude, this simply means that sea-level times will now reach new bests upon return to sea level.

How long does it take to adjust to altitude?
As already mentioned, in slow-speed endurance events, altitude-best performances will never match sea-level bests, but they will definitely improve with altitude training. In as few as two weeks, altitude performance will be noticeably improved.  Within about six weeks of altitude training, acclimatization will be quite complete.  However, improvement in altitude performance may continue for much longer as you learn to compete in the unfamiliar environment of altitude.  There are two distinctly different types of acclimatization taking place: a physiological one and a competitive one, with the latter type staying with you even after long periods of time back at sea level. You tend to always remember how to race at altitude.

What is the best altitude for living and training high?
Any altitude at which you can perform quality training is useful, but moderate altitudes, in the range of 1600-2600 meters (5000-8500 feet), are felt to be ideal. Flagstaff’s 2134 meter (7000 feet) elevation is certainly right in the middle of that range.  At this altitude there are seldom any problems with altitude sickness and normal amounts and relative intensities of training are generally easy to maintain.

How much improvement will take place with acclimatization?
Performance at altitude will probably improve about 4% with adequate acclimatization.  When returning to sea level, any improvement in performance there is more a function of how much room the individual has for making improvements.  There have been major improvements by some athletes, but, when this is the case, it is usually a matter of the individual not being in top fitness prior to the altitude stay.  Think of altitude training as just another type of training, and if you improve, then it was the right thing for you; if not, then, just like making a major change in weekly mileage, the change may have not been right for you at that particular time.

Does everyone respond the same to altitude training?
The answer to this question is definitely no, but more for personal reasons than physiological ones.  Those who respond best are the ones who have a positive experience at altitude, in terms of good weather, good training facilities, a friendly atmosphere, and all other things that make any training site enjoyable.  This is a big advantage to training in Flagstaff – there are great training venues, outstanding weather most of the year, good facilities and lots of support from throughout the community.  Being at altitude is just one of the factors that makes Flagstaff a great place to train.

How long at sea level can you take advantage of any altitude improvement?
It is best to think of any sea-level improvements in performance that are realized as a result of altitude training as permanent in nature, not limited by any number of days or weeks back at sea level.  Of course, to continue performing well for an extended period of time back at sea level, the athlete must continue to subject the body to adequate stress so that no de-training takes effect.