For access to all of our training, gear, and race coverage, plus exclusive training plans, FinisherPix photos, event discounts, and GPS apps, sign up for Outside+.
What you need to know before training or racing at altitude.
To escape the heat, many athletes take to the mountains. The only problem? The air is much (much!) different than at sea level.
Because we see decreased oxygen pressures and availability at altitude, there is a huge impact on performance. Your VO2max decreases by 7.7 percent for every 1,000 meters of altitude, so you must pace yourself differently. Thankfully our bodies are good at sensing oxygen availability and adjusting our efforts accordingly.
When to acclimate
Upon arrival at altitude, your body begins a process of acclimatization. Within minutes, it goes into respiratory alkalosis (breathing harder and expelling more carbon dioxide). The next day, hemoglobin levels are increased because plasma volume is contracted. Over weeks at altitude, the body begins producing red cells through the natural production of the hormone EPO, increasing our capacity to bind oxygen. Acclimatization happens in stages, with many adaptations happening in the first three weeks, but it can take eight months to get to the levels of someone who lives at altitude.
There is always a big question of when to arrive at a high elevation race. The idea of arriving the day before has been largely debunked. It is better to arrive a few hours before than 24–48 hours before, but since the former is really not possible for triathlon, arriving three days before is much better than two; seven to 10 days is even better.
Training at altitude
While it is tempting to believe that training at altitude will result in a supercharged athlete, living and training at altitude is generally a wash. Why? The benefits of living at high altitude—in this instance, 8,000-plus feet—are counteracted by the reduced ability to train hard at altitude. So maximal and even threshold efforts will be compromised. Base training at altitude is fine, but those intervals on your training plan will be really hard to nail.
In fact, recent studies have shown that living and training at altitude may actually be detrimental, reducing the athlete’s capacity for exercise and delaying recovery. Triathlon hotspot Boulder, Colo., at 5,400 feet above sea level, is technically below the point of “moderate altitude”—which begins at 6,000 feet.
“Live high, train low”
Research has demonstrated that intermittent altitude training is best, and that maximal benefit results from living high and training low. Athletes who lived high and were also able to do interval training at lower elevations showed increased VO2 at lactate threshold. These athletes showed an increase in productions of EPO at 30 hours and again at 2 weeks of living at altitude, with a corresponding increase in red cell mass. The best effect is seen after 3–4 weeks of living high and training low.
There are few environments that allow athletes to live high enough to optimize their adaptation to altitude and still be able to do interval training at lower elevations, making the “live high, train low” protocol inconvenient at best.
Instead of dealing with living in the perfect location, some athletes turn to an altitude tent. Researchers have looked at the benefits of creating an artificial environment with decreased oxygen pressure. Before you drop thousands of dollars your own tent, it’s important to note that you must spend at least 16 hours a day for three weeks in the hypoxic environment to achieve an EPO response. Despite this, in a study of athletes confined to an artificially created “altitude house” for 16 hours a day, performance failed to improve, likely due to the enforced sedentary lifestyle and boredom associated with living in confinement. Even though these athletes achieved the desired EPO response, there was no improvement in their performance.
Preparing for a race at altitude
– Your best option is to plan a block of base training at altitude, if possible. Athletes will need at least one week to acclimatize sufficiently and benefit from this block. If possible plan a week (or longer) altitude training camp 4–5 weeks out from your race. Increase your rest and recovery cycles after such a block. Peak performance will happen three weeks after this training block.
– Do some harder VO2 sessions at sea level to prepare for the race. Hill sessions are particularly helpful in simulating the feeling of working harder at altitude.
– Dehydration is a common problem experienced when racing at altitude. Relative humidity levels are lower and fluid losses are increased. Don’t forget to hydrate.
– Understand that your paces will be slower at these venues, and perceived exertion will be greater for any given pace or power. Be smart with your pacing and don’t go out too fast.