HR Lactate Threshold can't be right? | 80/20 Endurance

HR Lactate Threshold can’t be right?

Viewing 5 posts - 1 through 5 (of 5 total)
  • Author
  • #8202

    Hi David,

    Please help me with this. I think my HR lactate threshold is bonkers.

    Some facts to start.

    January this year I did your 30 min test on a track. Ideal conditions. Result
    4:09 min/km. Last 20 min average HR 158 bpm. My max HR by the way is 182.

    Now yesterday I did a 10 km run fairly flat on a trail but wide dog walking trail. 4 laps for the 10 km. Actually ended up being 10.55 km.

    My result was 4:19 min/km pretty steady the whole way. I was trying to do a 4:15 but couldn’t manage it. Been doing the maintenance program since Covid. But my HR was way in zone 5 for most of the race.

    I was HR zone 3 for 5 min, zone 4 for another 3 min then zone 5 the remainder. It took 11 min to reach 172 bpm and didn’t change right up to the 36 min mark. Steady around the 172 bpm. That was the point I sped up a little for the last 1.5 km and it then climbed to 180 bpm and overall it was a 45 min run and 10.55 km.

    I’ve been training mainly on pace but I do use the HR as a cap when going up one of my many hills in the area.

    Of course training peaks says 158 needs to change to 165 as my threshold.

    Please don’t ask me to run another test. I have still 3 more 10 km races every 3 weeks and finish with a half marathon. May be the track ideal conditions isn’t the same as a race and more adrenaline but obviously my heart can handle the 172 for a good length of time and was real steady on that.

    I start your marathon plan this weekend so would like to be close to ball park with the HR threshold.

    Appreciate your help.

    Thanks David,


    David Warden


    I regret the only way to resolve this is a two-hour time trial in Zone 4.

    Ha! What good is Forum Moderator Power if I can’t wield it to entertain myself?

    Your experience demonstrates the pitfalls of using heart rate to measure intensity. Heart rate is a great solution, but it can be all over the place due to external factors. I’ve said it over and over but it bears repeating: heart rate is not an output, heart rate is an indicator of your body’s response to an output.

    I have some comments and proposed solutions.

    First, your LTHR test from January is a long time ago. In January we were still shaking hands, going out to eat and packing into movie theaters. Your LTHR has both a) possible changed in 6 months of training and b) was also possibly influenced by January weather which is fundamentally different than July weather.

    Second, your LTHR of 158 is certainly wrong based on the 10K. Your LTHR is the peak 20-minute HR over a 30-minute TT. It is impossible to spend 40 minutes in Zone 5. If you did, that’t not your Zone 5, that’s your Zone 3.

    Your 10K now becomes the most recent LTHR test. Fortunately, I’m able to review your data directly since you have one of our 80/20 Bundles. I can confirm that your new LTHR is 174.

    But, is there a way off of this heart rate crazy train? Yes! Consider moving to Pace instead of heart rate to measure intensity. I propose your threshold pace is 4:26 per K, based on your 10K result (why a slower pace than your 4:19 pace? That’s because when racing, we use 60 minutes TT and when solo we use 30 minutes).



    Hi David,

    Thanks for the 2 hour time trial 🙂

    Interesting your response. Did you mean LTHR is Peak 20 min HR? I think there was a typo. I’ll use that for future reference. You are aware the 174 is only 8 beats short of my max HR. I didn’t know I was such an athlete 🙂

    January in NZ is summer so it was warmer then than now but HR was lower. So I don’t think it was the temperature affect. I have just come off 2 weeks night shift on Friday morning and didn’t sleep well the Fri and Sat night before the race so my HR may have been elevated because of that this time around.

    In October 2019 before all this Covid stuff happened I did do a HM at 4:29 min/km so I think this might back up your 4:26. I certainly don’t feel fitter and not been doing as much running as then but I did run a 4:09 for 30 min on a track. You think my fitness has dropped in 6 months from a 4:09 to a 4:26 or just a 4:26 is more realistic out in the field run?

    Can you tell me how you come up with the 4:26? It would be nice to know for future races instead of always asking.

    I have got your marathon pace loaded in my calendar and not HR. I just use my HR as my limiting factor when running up a hill otherwise my zone 2 run will end up being a hill repeat based on my HR.


    David Warden


    2-minute typo corrected in my post, should be 20.

    How do you know your maxHR is 182? Only a lab test can determine this. Age-based estimates or highest HR observed in training are not valid.

    The 4:26 estimate is from our 80/20 Zone Calculator. However, that is also just an estimate and I’ll be the first to admit that even our estimates are…estimates. An average 4:09 30 minute TT bests my estimate from a 40-minutes 10K when determining threshold. Use 4:09 for sure.



    Hi David,

    For starters I love the support you give here.

    I’ve looked back at 2 HM races where as i crossed the finish line I didn’t know to take my drink and banana or walk straight to the first aid tent. My max HR was 183 & 176. 20 min peak was 173 & 170 respectively. These 2 races were Sep 2019 and Oct 2019. You’re right though I don’t know how high it will go to and to be honest i don’t want to find out based on my feelings then. Last weeks 10km you know was 174 peak 20 min and 180 max. Once again i felt maxed out. 174 does seem more accurate threshold and i will use that. Thanks.

    I’m glad you say to use my 4:09 min threshold because otherwise my pace will need to be zone 3 before i reach zone 1 HR.

    I know you are an advocate of pace over HR. I always have in the back of my mind the HR is my temperature gauge. Its affected by heat and hills just like my car. In my car in future I’ll ignore my temperature gauge and just chug along anyway (my turn to make fun). If my HR is up higher than normal I’m sure there is a good reason. Shift work for one but it is in pretty good tune with my perceived effort and don’t get me started on cardiac drift. At the end of a long run and my HR has drifted up its because I’m not fit enough for that length of run and i would need to work on my aerobic fitness some more. But that’s a whole new discussion 🙂 That’s why running is so much fun and more interesting than throwing on a pair of shoes and just getting out there.

    Thanks David. You’re a great guy.

Viewing 5 posts - 1 through 5 (of 5 total)
  • You must be logged in to reply to this topic.

You have races.

We have plans.



- Access to all 80/20 plans

- TrainingPeaks Premium

- Workout Library

- 80/20 Endurance Book


30 day money back guarentee

Unlock your full potential

with our subscriptions