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 1 year, 4 months ago by ryanoelke.
    • This reply was modified 1 year, 4 months 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!


    Personally, I find Pace is my ideal metric for workouts. I generally use pace for foundation runs. However, if it’s a Foundation or Long Run that’s going to be on a hilly route, a trail run, or a very hot day, I’ll use HR or RPE, most often HR. That helps to ensure I’m not going too fast. Sometimes, if I’m doing a Foundation run on one of those routes and it’s with other people, I’ll turn off the HR alarm and just run for fun/feel.

    Either way, the key with Foundation runs is to ensure you’re not going out too hard and showing up fatigued for your 20% workouts.


    I have more the less the same issue.
    In most of my z1 and z2 runs my HR goes almost instantly outside of the zone, and if I have to keep my HR in the zone, I have to slow my pace to almost a brisk walk 🙂

    But if I look at the calculators on this page:

    The pace it gives sounds much better than what the HR zones would mean.
    Should I change from an HR-based plan to a pace-based plan?


    @marsnielson I recently have been exploring HR spiking in the first 5-10 minutes of my workouts before settling down. Now, it looks like in the end for me it’s my HRM being whacky because I’ve cross checked it against my Apple Watch and Whoop at the same time, which show a much lower HR to start, and ramping up like normal.

    However, in doing my research, a lot of folks have this happen because they’re not warmed up enough and your heart is just working to catch up with the work you’re doing, and then it will settle down into the zone.

    But funny enough, I was at first going off of the assumption that it wasn’t my HRM being whacky, but instead me not warming up enough, and so in the last few weeks I decided to go super slow in my foundation runs, either high zone 1 or barely zone 2, and you know what, it actually feels better to do that! I also then use my HR to check myself during the run, trying to stay on the lower end. My HR in foundation runs has improved a bunch, staying way lower than before on avg, and yet I’m also starting to speed up naturally, which is the crazy part, but not crazy given 80/20, slow = fast.

    Anyways, I definitely prefer pace now and get why they say it’s better than HR. I liked HR when I started off to make sure I didn’t over exert myself (including walking sometimes), but not I use HR as a secondary measure to help me dial in my workouts as needed, but mainly only for foundation runs.


    ALL of the better runners I know warmup fully. Especially when racing, they will arrive so they can spend as much as an hour loosing up and jogging to be ready.

    Heart rate alone cannot fully guide a race plan, heart rate becomes ineffective above the acidosis level. A pace or power plan can address all of the workouts.

    A workaround is to take the easy runs and open the workout on the Training Peaks workout builder and adjust the warmup to end on a lap button press. You can track heart rate on a data screen, then end the warmup when your heart rate settles, adjusting your effort accordingly, then continue with the rest of your workout.


    Hi folks. After reading all your comments, let me give you my thoughts on this issue, which has been widely discussed with Matt and David on previous forum posts and blogs.
    As a rule of thumb, the hierarchy of metrics for running intensity (from best to least reliable) goes like this:

    1. POWER.- (Gold standard for measuring intensity).But also the one that people are least familiar with and it’s pretty tricky to get the hang of it at first.
    2. PACE.- The easiest to use and the one that’s almost as reliable as power. (the only downside is that it’s not very reliable on hilly or technical terrain)
    3. HEART RATE.- Used preferably as reference or as a backup metric, since its highly influenced by a number or external factors (fatigue, weather, hydration, caffeine, etc..)
    4. RPE (Perceived Exertion).- Least reliable. Highly Subjective.

    All that being said, there’s a couple of caveats or best practice tips. If you don’t have a running power meter (Stryd Pod or newer generation Garmin devices) your best bet is to stick to pace, but keeping a close eye on your heart rate.
    So, for example, let’s say you Zone 2 pace is 6:00 – 7:00 min/km and your Zone 2 HR is 140 – 160 bpm.
    You want to star within that 6:00 – 7:00 min/km window as long as possible, but without your HR going over 160bpm.
    If you start seeing your HR creep above that limit, try aiming for the lower end of your zone 2 pace (7:00 min/km), but without going below. If your HR still goes above that 160 bpm limit; DON’T WORRY. Stay on pace even if the HR is a bit higher than it should (as long as it is slightly higher but not TOO HIGH). As a rule of thumb, you can get away with having your HR a zone above your target pace.
    So if you’re running in Zone 2 pace, its ok to be in Zone X HR, but not Zone 3 and above.
    Being in Zone 3 HR while running in Zone 2 pace could indicate that your Zone 2 pace is higher than it should be and you may need to re-test in order to properly set your zones.


    If only life could be so simple…

    Yesterday I did a fast finish run. The finish into a strong head wind. I prefer heart rate for this type of run, but I run with stryd and collect the power data.

    The finish was at a Zone III effort and both average power and heart rate correlated at the target effort. But, running into a headwind my pace was at the top end of my Zone II pace. The contribution of wind resistance is reported by Stryd a several percent increase.

    I run a hilly route, so I expect both pace and power to be all over the place. In my circumstance the averaging effect on heart rate provides a much better measure of the effort I am trying to achieve – while I am running.

    It was a successful workout, but had I attempted to use pace at the time I would have trained much harder than desired.

    My point is that one size doesn’t fit all and it is important to understand the strength and weakness of the tools and measures.


    “3. HEART RATE.- Used preferably as reference or as a backup metric, since its highly influenced by a number or external factors (fatigue, weather, hydration, caffeine, etc..)”

    I still have a lot to learn. I have been using HR to train. In regard to the above comment. Isn’t that why using HR is a good idea? As long as the HR monitor is accurate/consistent and your HR is high, for whatever reason, isn’t that a good indicator of how hard you are working? (other than caffeine)

    I have had races where I used pace, and even though my pace was in range, for whatever reason my HR was higher than it should have been. Which for me was a great predictor of how the race would develop. Which was me crashing and burning.

    My last two HMs I strictly used HR for the first 12km. In both races I finished strong with PRs. No burnout and no crash.

    I know I’m wrong as the experts above say pace training is better. Still, for me, pace training is what you “want” to do and HR training is what your body is telling you what you can actually do.

    Good reads here!


    “HR training is what your body is telling you what you can actually do”.

    Actually your body or HR are not the ones that tell you what you can or can’t do. It’s your mind. If you convince yourself that you can’t do something 10 out of 10 times you’re gonna be right. And if you teach yourself to cope with discomfort and with a little suffering; most likely you’re gonna surprise yourself.

    Using HR to regulate effort (specially in competition) can even be counterproductive. Because usually people tend to have higher HR in a race, due to excitement, adrenaline (the “heat of the moment”), so if you start convincing yourself that you’re working too hard just because your HR is higher than normal, then your brain is gonna start playing tricks on you and you’re gonna start thinking you’re tired when you’re actually not.
    We usually TRAIN by numbers “power, pace or HR” so that we are able to RACE by feel.
    A great piece of advice that I once got was: “Don’t look at your watch on race day. Don’t be biased by HR or pace and just let yourself go”
    More often than not, you’re gonna surprise yourself by the result and you’re gonna end up going faster than you thought.


    This thread is getting kind of long. I can see why, there is a lot of confusion on the issue. There is confusion about training vs racing, workout metrics, and the application of 80/20 plans to a wide community vs individual best practices. It would really help if the coaches could provide a resource explaining compromises.

    I’m pleased to see the evolution of 80/20 Endurance. The recently introduced coaching program could benefit with a discussion on when we might rely on a prebuilt plan, and when we should consider contacting a coach.

    I’ll confess, I’m a running junky. I follow the competitions on-line and examine the best runners in the world, trying to learn. I can’t say that I have seen but a handful of record attempts where athletes didn’t use pacers for a significant portion or all of their races (with lights). While I was watching the master’s competition last week I was struck by the number of times the winner of the 3000m race was consulting his watch throughout the race; and this is a world masters record holder. He’s not the only one, look at almost any distance race and you will see the leaders checking their splits.

    I would agree that there is a mental place where these athletes know when (and if) they can break. But that comes from what they leaned in their training…

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