Improvement for acclimated athlete going from 13’k to 4’k elevation?

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  • #61044

    I realize that I am asking the opposite of the usual question, but…

    Any quantifiable estimate of how much faster a fully acclimated skimo racer would be at merely ~4,000′ elevation than she was at ~13,000′ elevation?

    I am certainly familiar (on a personal level alas) with the reverse, i.e., how much *slower* a non-acclimated racer is at ~13,000′ elevation as compared to ~4,000′ elevation.

    The reason for my question is that the vertical ascent rate per hour of our fastest woman this past weekend at our Vertical race was almost exactly the same as the fastest woman at the A-Basin Vertical race the weekend prior to that.
    Our course was ~200′ vertical longer than the A-Basin course, and the final 200′ vertical was also flatter than optimal for skinning.
    Plus snow conditions were suboptimal. (We were skinning up under a blaze of snowguns — the uphill route was the only site of snowmaking activity! — producing a range of weird glop.)

    So those factors imply that our fastest woman would beat the fastest woman at A-Basin … except that even an athlete optimally (or closely thereof) acclimated to ~13,000′ feet must speed up significantly were she to compete at ~4,000′?
    (Our top guys though were definitely slower … even though their Strava segment rates at a popular dawn patrol route have been just as fast as the male A-Basin winners, but that dawn patrol route is only 1,000′ vertical as compared to 1,600′ for A-Basin, so their paces must be dropping off over a longer course.)

    Here is a spreadsheet for the data and calcs:
    https://docs.google.com/spreadsheets/d/1ieZbkzf9SJpkmqhJG9OJ-2RUStKcNCXNATGmUcGbR0s/edit?usp=sharing

Posted In: Skimo-racing

  • Keymaster
    Scott Johnston on #61324

    I’m not 100% confident in this but starting from first principles……..

    At seal level the amount of oxygen in the atmosphere is 21%. Are you go higher the the atmosphere becomes dense so the amount of oxygen take in with each breath will decrease.

    The “effective” amount of oxygen available at 13,000ft is 12.7%

    The “effective” amount of oxygen available at 4000ft is 17.9%

    So the air is 40% denser at 4000ft which means 40% more O2 molecules taken in with each breath. It stands to reason that the same person in identical conditions would be able to produce 40% more aerobic power at 4000ft than she would at 13,000ft.

    Sports like swimming a running have adjustment factors for times run at altitude and the adjustment factors correlate directly with the density of the air at the racing altitude. At 5000ft the air is about 25% less dense than at sea level and the correct factor is about 25%.

    I hope this helps.
    Scott

    Participant
    NE Rando Race Series on #62068

    So I updated my calcs to assess how much faster the A-Basin winner would have been at Stratton, also factoring in the reduced efficiency of the Stratton route.
    My conclusion was that, alas, the A-Basin female winner is faster than our Stratton female winner.
    As a test, I ran the calculations in reverse for myself, and almost perfectly predicted my actual A-Basin result based on my Stratton result.

    Participant
    brianbauer on #62162

    the problem is that math does not predict how an individual athlete will actually perform going from sea level to 10k feet etc. going from sea level to altitude is highly personal. some people suffer from Edema at 10k feet, some people can go from sea level to climb Mt Everest. There is however plenty of evidence that describes how altitude acclimated athletes perform when they compete at sea level. the only way to know how an individual will perform at altitude is empirical evidence…they need to do it. even then the advice is complicated: arrive at altitude 2 weeks early vs arrive as close to the altitude event as possible. when I ran Broken Arrow at the end of summer last year, I arrived from sea level 3 days early. I did short training runs and hikes for 2 days before the race. what I wanted to know was “how did I feel at altitude”. turned out I felt great, and this gave me the confidence I needed and went on to have a great race. for what its worth, on one of my prep days at Squaw, I randomly bumped into Courtney Dewalter as I was running down part of the course. she asked how I was feeling( she’s such a cool person !). I said surprisingly good. I explained that I had spent the summer running Ultras in east coast heat and humidity …she replied “ah, poor mans altitude training”…I believe she was right…stress is stress.

    Participant
    NE Rando Race Series on #62163

    Heh, poor man’s altitude training, I’ll have to remember that line!

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