Pace or HR for foundation runs? | 80/20 Endurance

Pace or HR for foundation runs?

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    Hi folks,

    My first post in the forum. Hope you are all well!

    I’ve been doing the Build Run Endurance plan for a while now and loving it. I’m using pace as the metric, but I also have a HR monitor. I have a question about which metric to use on foundation runs.

    The 80/20 Running book says that HR should be the main metric for zone 1 & 2 runs (text below). When I do this, my pace drops off quite a bit (and quite soon) as the HR increases.

    Meanwhile, the workout card for Endurance Run 5 talks about cardiac drift, and how it’s ok for the HR to go above zone 2 as long as I’m maintaining zone 2 pace (text below).

    So, I’m wondering which approach I should follow, and thinking that it might be different for different runs or even different within longer runs.

    Appreciate any guidance. Thanks, Simon.

    Text from 80/20 Running (book):
    “In low-intensity workouts (Zones 1 and 2), pace should not be your primary intensity metric. Runners more often derail their progress by consistently running too fast in low-intensity workouts than they do by occasionally running too fast in moderate- and high-intensity workouts.”

    Text from the TPs workout card for ER5:
    “Note that heart rate tends to rise over the course of an Endurance Run and may exceed Zone 2 toward the end even if you maintain a steady pace. This phenomenon, known as cardiac drift, is caused by fatigue-related efficiency loss and dehydration. When it happens, you do NOT need to slow down to lower your heart rate unless your pace or power is also above the Zone 2 range.”


    I’ve struggled with this as well. My HR tends to be all over the place due to variable weather, fatigue, hydration, stress, etc. I find it very difficult to keep my HR in Zone 2 without sacrificing form, even when I feel like I am running very very easy. It’s especially bad in hotter months (Arizona). So I prefer to use RPE to gauge my intensity as much as possible. From what I’ve read, RPE seems to correlate well with physiological metrics, so as long as you have a really good sense of what different levels of intensity feel like (and the discipline to be honest with yourself), it seems like it should produce good results.

    There is some great info about this in chapter six of the 80/20 Running book.

    But I am not a professional so please take what I say with a grain of salt 🙂


    When I returned to regular running last year after years of not running, I religiously used HR for all of my zones for the first 3 months. For me it was a ‘can’t go wrong’ approach from the perspective of making sure I wasn’t going too hard and injury prevention. It also helped me dial in RPE a bit.

    That being said I know David and Leyla have emphatically said that pacing is much better for training and more reliable, and I whole heartedly agree…now 😉

    After I felt I had a decent foundation, I switched to pace for my speed workouts, but kept my foundation runs and endurance runs to HR. This helped me transition to pacing, but still keep me honest in my long runs. I did this for 2 months.

    Now I’m only using pacing and it’s the BEST lol. So much easier honestly. But I have to say that I think I feel good with the pacing based plans because I built up a good foundation over many months AND I had 4 races that helped me dial in my zones. Pace can be controlled and honed in, which is good practice anyways. HR has too many factors and while it can be ballpark controlled, it can’t be done in a refined way.

    Now any time that I look at my HR after workouts, my HR is always really solid. There are discrepancies, but minor. For zone 1, sometimes for whatever reason, either my body or garmin is whacky, my hr says it’s above zone 1 for 5 minutes in the beginning, then settles way down, even though pacing was consistent. Zone 2 is like a glove, never ever off. Anything above Zone 3 is kind of silly for me to look at and HR is utterly useless. It never lines up due to lag, structure of workout, etc.

    Anyways, tldr: after a strong enough foundation, with really dialed in TT to set zones, I just don’t worry about HR and think it lines up pretty nicely anyways.

    • This reply was modified 6 days, 18 hours ago by ryanoelke.
    • This reply was modified 6 days, 18 hours ago by ryanoelke.

    Ok, thanks guys, interesting information. Being fairly new to running, I haven’t explored perceived effort much. Maybe it’s also my mindset, which tends more towards the empirical. I have a decent base now though, so maybe I will experiment more. I know from running on pace alone though that my HR zones can be quite disparate … maybe time for another test.

    Thanks for the input!


    BTW, Matt just published a great blog post last week that I think you may find relevant!


    Great article, thank you Desertrat!

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