Racing at high altitude: a myth exposed

August 27, 2007

My friend Henry Wigglesworth said the following in a recent email:

I just got back from New Mexico, where I had a disappointing race at the La Luz Trail Run. I was 90 seconds slower that last year, which is not a lot (1:43:03 vs. 1:41:33), but I frankly thought I was in a little better shape. Also, after the race this year, I felt like crap for about two hours. The main difference I can point to is that this year, I only had 18 hours to get used to the elevation change whereas last year (and the year before when I ran 1:36), I had 4 days. I know that the conventional wisdom is that it takes about 2-3 weeks to acclimate, and if you don’t have that amount of time (i.e., you have a job), then the best thing is to arrive the day before a race. But in my case, that did not seem to be true. I would love to hear your thoughts on this topic, since I know (along with the many well-intentioned volunteers at Western States) that you have a Ph.D. in physiology.

Henry, the conventional wisdom is not especially wise in this case. A close inspection of the relevant data suggests a very simple rule: the more acclimation time, the better. Yes, two to three weeks of preparation at altitude can be very helpful (and four to eight weeks is even better), but if you can’t get out to the race site weeks in advance, four days of acclimation is probably better than one.

The questionable “arrive right before the race” advice arose from an interesting observation made back in the 1960s by David Dill and his colleagues. Dill et al. found that, if someone was put in a low-oxygen chamber and immediately subjected to a VO2max test on a bicycle ergometer, he or she performed better than if transported to high altitude (with oxygen levels equivalent to those in the chamber) and given the same VO2max test after a couple of days there (Journal of Applied Physiology 21: 1168, 1966; Journal of Applied Physiology 23: 555, 1967; JAMA 205: 747, 1968).

Dill concluded that a gradual decline in exercise capacity takes place during the first two to three days of residence at altitude. This conclusion led to the recommendation that athletes should arrive at a high-altitude race shortly before it starts — that is, before the body suffers through its two- to three-day decline.

Dill never proved that performance is worse after two days at altitude than after, say, a few hours. However, his assumption of a gradual multi-day decline went largely unchallenged until a 2001 report by Adele Weston and coworkers (Medicine and Science in Sports and Exercise 33: 298, 2001). The subjects of this study performed various exercise tests 6, 18, and 47 hours after reaching an altitude of 5600 feet; they did significantly better after 18 or 47 hours than after 6 hours. A subsequent study (Burtscher et al., International Journal of Sports Medicine 27: 629, 2006) found that cyclists fared better in a 50-minute time trial at 10,500 feet when they had 45 hours of exposure to high altitude, rather than two hours.

Do these two papers give us the final, infallible word on high-altitude racing? No, of course not. But they do suggest that endurance performance bottoms out within the first few hours of arrival at altitude and then improves steadily after that. In other words, the more pre-race time you are able to log at altitude, the more success you are likely to have.

Better luck next year, Henry!


  1. The otherside of this issue is that not everybody has the opportunity, because of work and other obligations, to get out to higher elevations before race day. In this case if you can get the job done by showing up the day/night before the event then why not? I've finished a number of high altitude races (Hardrock 100 twice and San Juan Solstice twice and others…) by just showing up from near sea-level (Huntsville, Alabama ~600feet) the day/night before the event. The key for me is to try and be in as good a shape as I can before I go and race day realize that I won't be able to go 100% that I just lower my expectations a bit and enjoy the event. I agree that I could never be competitive unless I allowed for more acclimitization but for somebody who wants to just finish I think the day/night before routine can work. Also, is there any evidence that training in relatively hot and very humid environment helps someone adapt more quickly to running at altitude? I always wondered if that was a factor in my success at races at altitude with limited acclimitization having coming from training in a very hot and humid environment?

  2. Thanks for posting this Greg — I agree completely (fwiw), and had sent something similar to the ultralist on one of the occasions that this topic came up there. I've had a fair bit of experience around mountains (up to 6350m) and have spent time with others who have a lot more experience, as well as reading about it. Yet I'd never heard this idea about showing up right before an event, so I was quite dubious.But I hadn't seen any of the original research until you included the links to the papers, which is very helpful. As far as I can tell, the first Dill paper reports data on only four subjects, who just happen to be the four authors of the paper (??). Not very inspiring methods.

  3. Robert: I believe that training in a hot environment can lead to an expansion of plasma volume, which should mitigate the dehydration problems that often occur shortly after arriving at altitude. Living and exercising in the heat might also have put you in the habit of rehydrating aggressively, which would likewise help prevent dehydration…. Or maybe you're just really, really tough!

  4. I believe every additional day provides benefits. I ran the Leadville Marathon twice. The first time, I ran it in 6:01 – with a week's acclimation and felt fine afterward. The second time, I ran it in 6:19 and felt dizzy – I flew out the night before.I recently took a week's vacation in Utah at 6,500'. On day 2, I ran at 11:40 min/mi pace over hilly trails at an average heart rate of 123. On day 8 (last day), I ran 9:30 min/mi pace over the same trails at an average heart rate of 115. The facts for me are there…. one week is a lot better than no acclimation.

  5. Jay Birmingham observed that he had no problem going from (the heat of) Florida to (the altitude of) Colorado and running the Pike's Peak race, I believe, in his book "The Longest Hill".

  6. As someone who gets disproportionally affected by altitude, thanks, Greg (or should I say Doctor Crowther), for posting this with the references. An RD gave me the advice to show up late if you don't have a full week, but I wasn't adept at Googling the literature.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

%d bloggers like this: