Using a 5k to establish zones | 80/20 Endurance

Using a 5k to establish zones

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    I know how to use the 5k to establish pace zones using the calculator. For HR, I think I take the last 20 minutes of the 25:11 5k to establish my LTHR. I’m a little lost on power, though.

    Do I take the average power for the entire 5k, the last 20 minutes, or a percentage of either of those? I did 333 watts for the last 20 minutes, and 338 for the entire race.


    Hi Seth – this Intensity guidance resource has the info you’re looking for:

    Intensity Guidelines for 80/20 Running

    You can find your answers under “pace testing”. Given that it was a race I would use the full 5k power number and enter that into the 80/20 calculator, but Matt or David may have other recommendations.

    Good luck!



    If you’re using Stryd, you can calculate your power zones on the app using a 5K time.

    1. Go to the summary page
    2. Scroll down to the CP information
    3. Select the arrow to the right of your listed CP
    4. Deselect auto-calculate and select recalculate
    5. On the next screen, you can select 5K

    Then, once you enter your time, Stryd will calculate. If it’s a flat course without much wind, it should be accurate. But if you ran a hilly course, it might be off.

    However, if you recorded the 5K with Stryd, it will be on your power curve. You could do a couple of shorter best effort runs (3 min, 10-12 minute, both done the same day separated by about 30 minutes) which would dial in an accurate auto-CP.


    Thanks. I’ve been running with the Stryd pod for about 6 weeks now, just collecting data until I ran this race, then I wanted to switch to power for my next plan.

    My critical power is 339
    My 30 minute power is 318, modeled curve says 344
    My 20 minute power is 342, modeled 348

    Are any of these numbers useful as my run FTP?


    Hey Seth – Since you’ve only been using Stryd for 6 weeks, these would all be fairly recent runs. How old is the 30 minute test run? Also, what training program will you be following? One of the 80/20 programs? A Stryd program? Or another?

    I’ve done the 30 minute test run and Steve Palladino’s 3/10 and 3/12 tests to measure my CP. What I noticed is that Steve’s test always results in a higher CP for me. However, Steve’s training programs are more conservative with their easy run recommendations. Steve’s recommend easy effort is 80% of CP or lower, and 80-83% on long runs, whereas the 80/20 zone 2 goes up to 88% of CP. Using Steve’s test, but then basing your easy runs on 80/20 zones could have you pushing too hard on your easy runs.

    So I would recommend using the recommended method of whatever training program you will be following. If you’re using an 80/20 program, I would either use the 30 minute best effort run or do the 20 minute modified version. If you’re using a Stryd program, then I would recommend Steve’s test. That way, your training intensity should be correct. Does this mostly make sense? I hope this helps.

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