I'm reasonably fit, I run and cycle fairly regularly (at least 10k run total a week and 40k cycle) as well as some weightlifting (3x a week, currently running GSLP).

My running schedule usually consists of:

  • 5K race once a week (parkrun).
  • 5-10k endurance 'jog' (very comfortable pace).
  • 40mins interval/hill-repeats.

This weekend I did a 14k run for the first time at a comfortable jogging pace. I have done 6-7 10k runs in the last 6 months but had got some energy gels and wanted to push to a higher number with a view to doing a half-marathon next year. My 5k race pace is 5:10min/km and my 10k relaxed pace is 6:20min/km

I also recently invested in a heart-rate monitor (HRM) from Wahoo fitness (I have also checked its data against another HRM to confirm my findings). I used it on this run and knowing my maximum measured heart rate (from interval training) as 200...


Surely something is wrong? I could have happily continued running for at least another 5k.

Question: Would continuing to train at this intensity on my endurance runs eventually lead to a reduction in AvgHR?


Is this a sensible HR graph for a half-marathon?

Are the heart rate zones about right? If not, how could I work them out?

Should I re-evaluate what is a "comfortable pace"?

  • 1
    As much as I love technology, it could just be an error. I had a Garmin GPS watch that worked perfectly for about two years then suddenly told me I ran a half marathon in 15 minutes. A record I have never since been able to even come close to.
    – DeeV
    Oct 24, 2016 at 20:54
  • May I ask why you want to base training around heart rate? HR is widely variable day to day.
    – JohnP
    Oct 25, 2016 at 1:48
  • @DeeV I thought that might be the case but the data from another 10K run backs it up. It measures my resting heart rate correctly too.
    – John
    Oct 25, 2016 at 7:05

1 Answer 1


I think your maximum heart rate is programmed in too low, or the HRM is incorrect. It is possible to run as much as 95% during a half marathon, and I've actually managed just under 92% in one race. Ive heard somewhere that some professionals aim for just as much for the marathon, but per McMillan's Zone Graph this unlikely for marathon times that are 2.5 hours or more.

McMillan's Zone Graph can be used for determining your heart rate zones. I use these following rules for myself based on that and other reading. Threshold for Z2 to Z3 is approximately around the limit of what an easy effort is and around the time you start to breath more. Threshold for Z3 to Z4 is the lactate threshold which is your hour race pace. Threshold for Z4 to Z5 is the VO2max threshold which is your eight minute race pace.

Optical based HRMs seem to get off track by several different things, and I have to wear my kinda tight thanks to my monkey hairy wrists. A few runs ago it seems to have measured my cadence when I wore it one notch looser, and at your pace I bet the recorded heart rate is pretty close to your running cadence.

Figuring out your maximum heart rate is difficult and many people seem to have a problem determining this. This question has some good information on trying to determine it, how it changes from different exercises, and how much it might matter to your training.

Beware of any heart rate that is too far off from the common estimate of HRmax = 220 - age. This formula is not accurate but it is generally not too far off, so anything 20 bpm or more off should be suspect. Technically maximum heart rate occurs right before passing out so keep this in mind when using intervals to estimate your HRmax.

Use effort to determine your comfortable pace. Usually this will occur for the same HR but many things can change your HR from normal including heat, caffeine, and sore muscles. Cant rule out a health condition too - see your Doctor just in case.

The heart rate is a great truth-meter that can tell you if your pushing too much or not hard enough, but keep in mind the zones will change as your fitness changes. Enjoy your running.

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