Pace-Based Zones—How bad is it to be in Zones 3 or 4 in foundation runs? | 80/20 Endurance

Pace-Based Zones—How bad is it to be in Zones 3 or 4 in foundation runs?

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    Okay, “bad” may not be the right word. Unhelpful may be better (but there is a character limit on the titles!).

    I keep getting stuck in pace-based Zones 3 and 4 on my easy runs.

    (I am slow; 11 min/mile threshold pace.)

    The runs themselves feel fine and easy. I don’t feel like I’m pressing.

    However, trying to stick at the slower Zones 1 and 2 in foundational runs ends up hurting. Hurts my knees; hurts my shins; hurts my achilles. My stride is less efficient at handling the weight and pounding at these slower zones, and I feel it.

    My stride at the faster zones, however, doesn’t seem to create the same wear and tear issues.

    I know foundational runs are intended to help build up stamina——both cardio-stamina and sheer physical stamina. My understanding is this is one key to avoiding injuries as mileage increases.

    However, if I’m getting injured trying to stay in Zone 1 or 2, but Zone 3 or 4 seems to be fine, how unhelpful is it to do my slower runs in these zones (and my slower intervals)?

    Is it possible I need to try and recalculate my threshold?

    I’ve run it based on a trial mile I did on a track and on a recent 5k distance (not race). Both end up around 11 min/mile threshold.

    Maybe I need to go do that mile again and push harder?

    Alternatively, I think I could actually hit the HR or Pace-based Zone 1 walking. Is walking a better solution?

    I’m just struggling to figure all this out, lol.

    Matt Fitzgerald

    Overall, tissue stress is lower at slower paces. You’re just not used to running that slow, so your body is adjusting. It will adjust, though, if you stick with it. And the other thing that will happen if you stick with it is that your Zone 2 pace will get faster.

    You can ease the adjustment somewhat by replacing some of your Foundation Runs with nonimpact cross-training sessions for a while.

    A one-mile time trial is not a valid test for determining pace zones, but it wouldn’t hurt to try another 5K time trial.


    Would hiking instead of cross training work? Hiking I can get into the HR zones for Zone 1 and 2, and it does not cause the nagging injury issues. (I live near some great hiking trails.) Previously I was training using a Couch to 5K plan and would use the off days for recovery by hiking.

    I guess here’s another question——if my legs can handle the pounding at Zone 3 or 4 (let’s presume), do those zones create more of an issue for building my cardio systems up?

    To be honest, my cardio is more my worry. My legs have never been my weak point, but my breathing always has. In high school cross country I could run sub 20 5ks, but would always perform stronger at longer distances. (I ran a sub 55 minute 10 mile, and a sub 38 10k.)

    In reading more later in life on training, it seems I was hitting my threshold too soon in the shorter, faster races, while the longer races let me stay sub-threshold and perform better. (I was also always that runner at the end heaving for air, jealous of my teammates who’d be barely out of breath and catch it back up in a few moments post-finish. Lol.)

    I’d like to push my HR/cardio thresholds up.

    So, to sum up, if I am in Zone 3 (assume HR, since the HR and pace zones for my runs track fairly on point) on foundational runs, will that be detrimental to the 80/20 approach to improving HR thresholds?

    (And I’d love to HR train, but I have an Apple Watch. Looking into a Garmin, but don’t have it yet.)

    I will try and do a 5k trial. The 1-mile is more time accessible (and I have a track next to my house; an old, 1970s concrete track, but still 400 meters roughly, maybe 440 yards since it’s from that time). But yeah, I’d imagine a 5k is better, and my 5k route is still fairly flat.

    In the end, I suspect you’re right and I just need to suck it up and try and run slower and get used to it.

    Thanks for the input! And apologies for my rambling. Still getting going and only now getting to my second cup of coffee.



    My experience is that building your “aerobic engine” can take quite some time (years), so I would recommend patience and sticking with the slow pace. Over the last 2 years or so my “slow” pace has become reasonably fast with 80/20.

    With the 5k or 30 minute test, it’s an absolutely all out effort and nothing left at the end. If you are new to this it can be difficult to master. Practice makes perfect here. For your run test it’s probably best to look at the pace you ran last time and see if you started off to slow / too fast etc, and see how you can adjust accordingly. Your HR zones will be an outcome of your paced effort.

    Keep with it, as your body will adapt and adjust, and you will see the benefits!

    Hope that helps



    I think this was answered in the above but just want to make sure. Just started looking at 8020 and also Training Peaks so don’t fully get Threshold pace.

    According to TP, based on my 5k time (36:15), my 8020 Z1 is 15:22-19:27 and Z2 13:46-15:22. Z1 is a walk, but for Z2 should I really try to “run” that slowly or can I run a little faster with frequent walk breaks to build up running form?

    Just want to ask from the perspective of the truly slow since so much running advice seems to consider 10-11M/M as “slow”, not sure how much of it applies to the even slower 13-15m/m crowd 🙂

    Matt Fitzgerald

    I wish there were a solid scientific answer to this question, but alas there is not. What I can tell you is that the human body does not respond to average intensities, it responds to specific intensities, so a run-walk is not the same as a slower run resulting in the same average pace or heart rate. We can also be reasonably certain that the 80/20 rule applies to even the slowest runners, meaning you will get fitter faster if you do 80 percent of your training in Z1-Z2, even if this requires a lot of walking. That being said, I think a more creative approach to 80/20 training might be needed for the “13-15m/m crowd,” as you call it. Specifically, I’m thinking it might be helpful to distribute the higher-intensity work across a greater number of weekly training sessions rather than concentrating it in a couple of sessions, as our existing plans do. I’ll put some more thought into this.


    I was in that crowd.

    Looking back, I would have benefited from an introductory plan in order to develop the foundational fitness and establish reliable thresholds necessary to begin one of the race specific plans (which are already great).


    Thanks for the reply Matt. The “responds to specific intensities” nails it for me.

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