Effect of elevation on long climb FTP test

[bsamm]

Last weekend I did what was basically an FTP test up a long climb that started at near sea level and ended just over 4000 ft. It took me 57 minutes at 276W. Would it be reasonable to assume that my sea level FTP is a few percent higher, say 276/.97 ~ 285? I should probably mention that I do almost all my training near sea level, so I wasn't at all acclimated.

 

[WattsAMatta]

I posted a related question a few years back and ACoggin responded with a link to some altitude/power data. The link is no longer valid, but I recall that the rule of thumb that applied to my situation (circa 7000') was to expect a 1.5-2.0% decrease in power output per 1000 feet of elevation gain. I think that the rate of decrease was smaller at lower elevations, and got progressively worse as you went higher. Sorry I don't have more than a vague memory of the data, but if you assume that the average elevation of the climb is 2000', then your 3% adjustment seems reasonable.
-- Bryan

 

[lanierb]

I don't think 4000' makes enough difference to worry about.

 

[hammonjj]

You could say it is a little higher, but is a handful of watts really going to matter?

 

[iZnoGouD]

4000 feet is nothing

 

[ric_stern/RST]

not to a lowlander!

Anyway, you'd expect to lose in the region of 4 to 7% of your FTP at ~4000 feet, depending on a variety of factors including whether you're acclimated or not, etc.

Of course though, your entire TT didn't take place at 4000 feet, but you'd expect a drop off in performance from about a 1000 ft (probably about 1% again depending on a variety of factors).

Ric