Long Run Intensity | 80/20 Endurance

Long Run Intensity

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    I have a question about long run intensity. Obviously, the 80/20 programs suggest zone 2, after warming up for half a mile. But there’s a pretty good range within zone 2. I’ve heard some say that you should just keep it easy for aerobic development, which would usually equate to the lower part of zone 2. But I’ve heard others say that you should push the top of zone 2 for more fatigue resistance.

    Any suggestions here?

    Matt Fitzgerald

    Runners with lower levels of fitness are almost automatically going to be near the high end of Zone 2 in long runs. For them, it’s important to limit the long runs to a duration that doesn’t lead them into exhaustion.

    For fitter runners like you, I recommend treating most long runs as long easy runs, and pacing them accordingly:

    Why Your Easy Run Paces Should Be Wildly Erratic

    Your friends who tell you to do your long runs well below the VT1 are right. Your friends who tell you to do your long runs at or very near the VT1 are also right. In other words, you should do both, depending on how you feel. This ensures you get what you need from each of them.

    As a final note, fitter runners should do some structured long runs with moderate- or high-intensity segments built into them. This takes the pressure off Zone 2 long runs to effect high-level aerobic development.


    Thanks for the response. That helps. For the past few weeks, I’ve been doing everything designated as easy (warmups, easy runs, recovery intervals, cool downs, long runs, etc.) by RPE. Some days, this is really slow and other days it’s faster. Some days it’s a fairly consistent pace and other days it’s really erratic. But it’s always based on what feels comfortable and easy that particular day, plus it’s trending faster.

    Since I started doing this, everything zone 3 and up is getting faster with less effort. So as far as I can tell, it’s working.


    Long runs terrify me. We recently laid in the Endurance Plan to my calendar, and at Level I it builds to a 3-hour run at the same intensity as my daily foundation runs. I’ll give it a try, but it made me look at some possible accommodations for this old middle distance runner.

    I’ve experimented with converting the pace based long runs to heart rate workouts. Simple to do on Training Peaks; just go into the workout builder and change from % Threshold Pace to % Threshold Heart Rate, then save the change. This exploits the fact that the 80/20 Calculators and Plans use higher percentages for heart rate, so the zones are reduced by 5-6 bpm.

    Using heart rate instead of pace appears to be in line with Matt’s article, and this accommodation “should” allow me to get the time in on the rolling hills I run and the summer temperatures quickly approaching…


    This thread gave me an idea to use on my endurance run last Saturday. It called for a 1:20 run at Z2. I use pace as the intensity metric, so my zone alarms on my Garmin are based on my pace zones. I was running along at my normal pace/RPE for a zone 2 run. I noticed my HR was 10 bpm or so below my HR zone 2 limit. I figured what the heck. I uppped my pace a bit to bring my HR to within 2-3 bpm of my upper limit. Going up any incline, I dialed it back a bit, and any decline I bumped the pace up. I finished it a good 30 seconds/mile faster and my HR never touched zone X. Thanks for the great idea!

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