Altitude and Aerobic Performance

In my first post on estimating your FTP (Functional Threshold Power) I mentioned that altitude was a factor since FTP is a metric based on aerobic function. The bottom line of that portion of my blog post was that as the altitude increases aerobic function decreases and so FTP decreases. And as you acclimate to a new, higher altitude your aerobic function and FTP improve, but they never attain the level you would have at a lower altitude.

So how much does increasing altitude decrease your aerobic performance? The accompanying chart is from studies by Basset et al (1) and Peronnet et al (2) to find the answer to that question (click to enlarge the chart). The data comes from world-class road cyclists and runners so there may well be some population-specific results here. But we can probably use the data with well-trained endurance athletes to get general estimates of the effect of altitude. Peronnet’s data is not divided by acclimatization, but the athletes were probably acclimated given that they were competing at world-class events.

Note the increasing spread in data between the two studies as the altitude increases beyond 5,000 feet (1,516m) with Peronnet’s showing slightly less loss of performance at increasing altitudes. Generally, however, they are quite close.

  So as you can see here, if you live and train at about 5,000 feet you could theoretically expect a 5% increase in FTP and performance if you went down to sea level to race. Conversely, if you came from sea level where you live and train to some place like Denver at about 5,000 feet you might expect, initially, about a 9% drop in FTP and performance. If you arrived a few weeks early allowing your body to fully adapt that loss of performance would theoretically and gradually shrink to about 5%.

At another time I’ll write about the adaptation process when traveling to races at a higher altitude.

1. Bassett, D.R. Jr., C.R. Kyle, L. Passfield, J.P. Broker, and E.R. Burke. Comparing cycling world hour records, 1967-1996: modeling with empirical data. Medicine and Science in Sports and Exercise 31:1665-76, 1999.

2. Peronnet, F., G. Thibault, and D.L. Cousineau. A theoretical analysis of the effect of altitude on running performance. Journal of Applied Physiology 70(1): 399-404, 1991.

Comments

[Don]

Near the end of your article you commented on "if you live and train at about 5,000 feet you could theoretically expect a 5% increase in FTP and performance if you went down to sea level to race" I have always wondered two things:
1. How long would the effect last?
2. Would tapering at 5000+ have a real impact if you train at 0 tapered at 5k and raced at 0?

[Joe Friel]

Don--thanks for your comment. The effect might last as long as 30 days but would probably decrease in the last several days. 'Tapering' essentially means resting (it's actually a bit more complex than just that). If you rested, regardless of the altitude, you would experience an increase in form.

[Racer Ex]

Joel, having lived and trained at altitude for quite a few years, the chart mirrors almost exactly the percentages that I use to adjust my FTP in WKO.

One thing that often gets lost in the altitude conversation is the impact on muscular endurance and power; while many people gain an aerobic advantage from altitude,there's the downside of training at lower power levels. Preparation strategy needs to take this into account.

[Joe Friel]

Racer Ex--Yes, you're exactly right. While aerobic power is gained at altitude, muscular power is lost. One simply can't train at as high an intensity (as measured by power, pace or speed--not HR) for endurance events. You'll simply be going slower/less powerfully at any given HR for extended periods of time.

[Andrew Coggan]

To give credit where credit is due: Charles Howe is the person who produced that table, which first first appeared in the FAQ for the wattage list way back when it was hosted on topica.com.

[Joe Friel]

Thanks, Andy. I had it in my archives but didn't recall where it came from.