Need Help Setting HR Zones | 80/20 Endurance

Need Help Setting HR Zones

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    I’m having some trouble figuring out my HR zones. I’m a 49yo trail runner that’s trained with HR for 10+ years but only figuring out that I need to stay in my lower zones the majority of the time about 5 years ago (partly due to reading 80/20Running). The last couple of years I experimented with low zone training (MAF & UphillAhtlete) and wasn’t satisfied with the results I was getting so I’m back to 80/20 methodology.

    My problem is that I’m having trouble setting AnT and AeT as I’m getting mixed results from methodology testing.

    Using 80/20 zones, I have estimated my LTHR at around 162 which leads to the following zones:
    1-117 to 131
    2-131 to 146
    X-146 to 154
    3-154 to 162
    Y-162 to 165
    4-165 to 170

    I’ve been running at these zones for roughly the last 2 months – averaging about 35mpw. This has represented a transition/down cycle from a previously much higher volume when I was at 45-55mpw most of the time training for ultras (I also cross trained 3-5 hours per week).

    I ran a hard trail 7 miler about a month ago that took almost 55min to complete and I averaged 165bpm which might indicate my LTHR is higher than 162? Previously I based that LTHR on some time trials of 45min, taking the average of the last 20-30min.

    My concern is that my AeT or ventilatory threshold may be lower than 146 and therefore I’m doing my easy running too hard. Doing a nose-breathing or talk test on a treadmill seems to indicate a lower AeT and I concurrently performed an HRV testing using this protocol which showed the threshold more in the upper 130s.

    One of the tenets of the Uphill Athlete methodology is that if there is a wide discrepancy between AeT/VT and AnT/LTHR then that indicates significant aerobic deficiency. So even though I’ve sort of left that methodology behind I am still a little concerned that my 2 thresholds are so far apart – but mostly I just want to get my zones dialed in properly for 80/20 training. I’ve long trained by HR and I’m comfortable with it and can stick to zones but if the zones are wrong then I’m wasting my time.

    Any thoughts from others on what I’ve listed above? Appreciate any discussion or advice.


    Hi Brian – I generally like to keep things simple. I read in your post that you estimated your LTHR from a few different runs and you are getting some results that don’t feel right.

    My advice would be to do the gold standard field run test of 30 mins described in the 80/20 run or triathlon book. This run needs to be your all out effort but well paced such that when you get to the end there is nothing left. Your LTHR is the last 20 mins of the run, and your LTH pace is the average of the whole 30 mins. I did this last week and it’s very hard indeed – I have rarely reached my peak heart rate outside of this test.

    If you ran a race in which you had a higher Heart rate than your tests or estimates for LTHR, it probably indicates that they were not your “best effort”.

    So in summary I would recommend the 8020 field run test protocol and let that reset and redefine your zones.

    Hope that helps


    Matt Fitzgerald

    Thanks for weighing in, Gareth.

    Brian, as a supplement to Gareth’s advice I would just remind you that you can do informal talk tests at any time during low-intensity training sessions to ensure you’re below VT1. Doing this somewhat regularly will counteract the one-size-doesn’t-quite-fit-all nature of intensity zones and ensure you execute these sessions as intended.


    Thanks both.

    Matt – with regard to the talk test, is there a different talk test than what’s described in “8020 Running?” I know that one is mentioned specifically around the LTHR, meaning you should be able to recite the pledge of allegiance at just under LTHR.

    I’m familiar with the usual talk-test as well that you should be able to be “conversational” when under VT1/AeT. I’m assuming that’s the one you were referencing above.

    Matt Fitzgerald

    That is correct.

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