Running a marathon by Heart Rate


I've been training for the Berlin marathon which is coming up the last Sunday of September 2015. I'm trying to calculate my optimum pace currently so I can really start focusing on my pacing and race management rather than increasing aerobic and anaerobic ability. I'm feeling confident of completing the distance and initially my plan was to complete the course in around 3hr45mins or less. 

According to my running watch my VO2 level is 50; I'm aware this won't be 100% accurate. My maximum heart rate appears to be 190bpm. What other information would you require to predict my target race pace? I'd like to run by heart rate as I find it easier to monitor.

I've previously managed a 19:45 - 5k // but currently at about 21:30

44.45 - 10k // currently at 47:30

1:43:00 Half-Marathon // currently at 1:48:00(ish)

Another recent time was 10 miles - 1:22:02


Again, my watch predicts a 3:20:00 marathon (This seems ludicrous to me though!)


Please feel free to ask for any other information you might require.






  • I'm not keen on running a marathon to heart rate. I always suffered with cardiac drift - so as the speed kept the same - the HR elevated with distance.

    How can your watch predict a 3.20 marathon if your half PB is slower than the time you'd need to be at in the marathon ? thats bobbins that is.

    You'd be better off getting a half under your belt so you have an accurate half time.

    Say its 1.45.

    Then Double it - give you 3.30 and add 20 mins - gives you 3.50.

    8.46 minute miles is what I'd pace to.

    Make sure you have your 20 milers in, and that you aren't racing them.
  • MillsyMillsy ✭✭✭
    If you run the whole race at a set heart rate then you will just slow down at the end.

    Try to run at an even pace for the whole thing and not really worry about heart rate.

    Edit, looks like Cougie beat me to it. "Cardiac drift" that's what I was trying to describe but couldn't think of the word.
  • PhilPubPhilPub ✭✭✭

    First off, I agree that your watch is being rather optimistic.  McMillan reckons your 3:45 target is a lot more realistic; according to his time predictor that's equivalent to:

    HM 1:46 / 10 miles 1:20 / 10k 47:57

    ...although from this, I would say that you might want to be even more conservative, since on current form you're inside the pace at 10k but outside for the HM, which suggests a lack of endurance.  (But still plenty of time to work on this!)

    As for using HR for pacing, I think you need to be careful. You can read about estimates for what % max HR you should run for a marathon but as with all these things, people vary.  (For the record my figures are roughly: max HR 200, marathon HR 170 = 85%...)

    Are you used to using a HR monitor in training?  Do you know what typical values you get for easy pace/different race distances?  I think some trial and error might be called for; try out a few "marathon pace" tempo runs, working at say 3:45 target pace, and see what HR readings you get.  Then flip things around; do another run sticking rigidly to a target HR, say 85% max, and see what pace comes out.  How do the figures come out?  What pace feels sustainable?  Repeat each session maybe fortnightly, see if your pace improves/HR drops...  

    This might help you decide on a target pace nearer race day, and also you'll have a better handle on what your HR target will be for the race, if that's how you want to pace it.  OR go out at a target pace, and just monitor HR to make sure that your effort level is stable.

  • PhilPubPhilPub ✭✭✭

    x-posts.  I didn't factor in cardiac drift, which is definitely a consideration, although I DO think that pacing according to HR is useful, particularly to ensure you're not going off too quick and that your effort, as opposed to actual pace, is even.  Hopefully if you're well trained, cardiac drift will only come into play very late into the race, at which stage you can safely ignore the HR monitor and just run with whatever you've got left.

  • NayanNayan ✭✭✭
    The 'HADD' document (link at start of thd HADD thread) is quite useful for this kind of thing. If you have a good idea of your heart rate at vo2 Max pace, threshold pace etc you can use this to work out what sort of average pace might be sensible over a marathon.

    Ie if your max HR is 185, then the sort of pace you could run at for an hour but holding your HR dead flat at 150bpm won't be too far from marathon pace. And I mean run for an hour with no drift, and feel confident you could Cary on for another half hour at that pace without blowing up. And thAts assuming you do s proper marathon build up in training

    Works for me anyway.

    As other have said- when you put this into practice over 26.2 miles your heart rate will drift up towards the end and it'll eventually feel like a hard 5k race effort to simply hold goal pace.
  • I use the HRM for marathon training and for the marathon.  My HR goes from 75% of max for the first few miles to 85 / 86% of max for the last few miles, and it repeats it self in most of the marathons I have ran.  Averaging about 82 / 83 % of max.                                                                                                                                  You say your max  "appears to be 190 " how did you come to that figure ?. Without knowing what your max is the training that you do will be in error.

    One further point

    Looking at your times for 5k and half marathon, you do need to do some aerobic training ie long slow runs.

    As the others have already written and I agree with, train, train, and train and then work out what you can expect to run the marathon in.

    Hope this helps in any way yours Mok



  • VDOT52VDOT52 ✭✭✭
    Look up the marco calculator. It uses a recent 10k or half marathon and your max heart rate and sets out a race plan. I've not used it but it looks good and some people swear by it. Having looked at it it shows/allows for cardiac drift. Well worth a look.
  • I could be wrong - but it looks like you're almost running the marathon on autopilot with the fancy watch.

    Its great that it can give you estimates of marathon time (somehow) but its clearly well off the mark and its good that you can see that.

    If you had some kind of history of running to HR and you can see that it works then I'd feel happier about doing it. I used to train religiously by HR for my cycling events but it seemed easier on a bike and they were only up to 2 hours long.

    If you're running a marathon and doing over 3 hours then I think its likely that your HR will drift. I know mine did the one time I went by it.

    For me - I'm better off pacing to a realistic time and not worrying/knowing what my HR is.
  • VDOT52VDOT52 ✭✭✭
    Should have added that The marco gives paces plus expected HR at that pace, so is sort of a half way house towards raving by HR.

    The times predicted look fairly realistic too.
  • Ok thank you everyone. I'm going to strive to provide some info relating to my ability and training.

    As far as training goes. I've been averaging 33 miles each month since January. A mixture of intervals, hill repeats, tempo runs and long slow runs. I'm up to 16 miles now. I'm planning on doing an 18 mile run within the next week and a 20 mile run before 2nd/3rd weekend of August. 

    May - 34.00 miles

    June - 42.60

    July - 46.86 (likely another 18ish miles to add)

    August - 65/70 miles forecast

    September 30-35(ish)

    So I'm more then confident in doing the distance without any major surprises. Perhaps I'd ask what distance long slow runs should I do between now and September 1st?

    I have a Garmin Forerunner 620 and that's where I'm getting my readings from. I'm very sceptical of them thus far and that's why I'm providing all the information. As it stands my readings are:-

    VO2 Max of 51 - Which I assume is based on HRM.

    5K - 20:24 

    10K 42.19

    HM - 1:33:41

    Marathon - 3:15:07

    I feel that 5K time is reasonably accurate. I just, this evening, ran 10K in 46:21, so the predictor is well out. And huge discrepancies between HM & M times.

    I think I'd be delighted with a time between 3hr50 & 3hr40 - So my question to you all would be is there anything that I've stated that would suggest that I'm seriously incapable of that finish?

    I was fond of the heart rate method as the other day I warmed into my run at 150. Moved up to 160 after a few miles. Stuck and 165 for a good period and finished in at 175. I just felt very strong and comfortable the whole time. But I understand most of you are more experienced and respect and understand your suggestions.

    Lastly, I'm very quick more of a sprinter and I often find that I've got a great kick at the end even if I feel like the pace is getting to me earlier on. For example, I finished with a 6:40 mile at the end of a 13mile run recently. - Here is my profile if anybody wants to have a look and see. 


  • MillsyMillsy ✭✭✭
    Is that 33 miles a month or a week?

    How are you working out those times above?
  • A month

    "How are you working out those times above?"


    Sorry I don't follow

  • TeknikTeknik ✭✭✭

    "I think I'd be delighted with a time between 3hr50 & 3hr40 - So my question to you all would be is there anything that I've stated that would suggest that I'm seriously incapable of that finish?"



    The bit where you said you're running on average about one mile per day?

  • So how many miles a day do I need to average Teknik?

  • VDOT52VDOT52 ✭✭✭
    Is this a wind up? image image
  • No. I'm really lost. Not sure how this has gone so off on a tangent? 

    If it makes everybody feel better. I shall run 20 miles on Monday/Tuesday so we have another time.

  • MillsyMillsy ✭✭✭
    What marathon plan are you following that prescribes 30 miles A MONTH!!!

    The times you are mentioning are ones that people on 30 miles a WEEK would be proud of.

    I wouldn't worry about heart rate, VO2 whatevers , tempos fancy watches etc. You need to get out there and just run more miles.
  • TeknikTeknik ✭✭✭

    I'm sorry Kenton if I appeared so dismissive: having checked your profile I applaud you for slimming down from 20 stone to have been able to run a 19:45 5k. image

    I do however feel that even your August peak, planned at about 15m per week, is going to mean you'll be walking the last 8 miles of your marathon...

  • Millsy. My runs do not take into account that I was playing football matches Saturday and Sunday between January & April - You could add at least 10 miles a week to those months. I decided to knuckle down between June and August (solely running) and my mileage for July and August will be in access of 130 miles (forecast minimum)?

    Thanks Teknik. I understand your queries and concerns and was well aware to expect this type of feedback. I need to get in 2 x 20 milers and maybe something longer between now and 3rd week of August I guess. How many miles per week would you prescribe between now and end August? 


  • MillsyMillsy ✭✭✭
    Are you following a proper training plan?

    Your 5k time shows you have some natural talent and speed but you need to work on your endurance base which will come from more easy miles.

    How did you get on in the Berlin Half last year?
  • Honestly, no. I'm doing a mixture of long-slow-runs, tempo runs hill repeats and interval sessions. I do my long-slow-runs very slow etc... So not a complete novice. A lot of holidays in June hindered my training for that month. But I feel 70-75 miles in July and 80(ish) in August is ample amount for someone with a decent base. Then I'll ease off in September and just keep myself ticking over. 

    Ye. I'm at 14st5lbs as well currently. So loosing 12-18lbs would make a big big difference.

    I managed 1:42:21 

    - Terrible IT Band Syndrome problems 4-6 weeks before

    - Foolishly wore a Nike Combat Long Sleeve layer under my running top - it was something like 22-24 degrees from memory and I was very uncomfortable.


  • MillsyMillsy ✭✭✭
    Apologies for another couple of questions

    If you are averaging 80 miles a month in August what distance are your long runs like and what other running are you doing in the week.

    In your last big month you would be looking at a long run of 20 is miles every week so 4 of those brings up your 80 for the month already.
  • VDOT52VDOT52 ✭✭✭
    A definite wind up. A funny one too image
  • A typical week would include:-

    1 tempo run - 20 minutes at 6.40 // 6.50 pace. (+10 min warm-up and cool-down).

    A long slow run - (Between 12-15 miles - at 9:00 // 9:30(ish) min miles)

    A 5mile run at 7:30 // 7:45 pace


    1 Mile repeats at 6:45 pace - (4x or 5x)

    Hill Repeats (4 or 5 x 1km at 4:20(/km) pace - All ran consistent.


  • VDOT51 wrote (see)
    A definite wind up. A funny one too image

    Please ellaborate?

  • OK I think you have 9 weeks left to train ? You can allow 2 weeks for taper.

    The predicted time I gave before relied upon you being as well trained for the marathon as you are for a half. I don't think you are/will be. It's far easier to run the shorter distances.

    Your typical week would seem to be about 20 miles ? So a typical month would be 80-100 miles ? But it isn't ? So you must be overstating the typical week ?

    Assuming you are up to 15 milers then., I;d think about putting the long runs in something like this

    Week 1 18 miles LR

    Week 2 15 miles LR

    Week 3 20 miles LR

    Week 4 14 miles LR

    Week 5 20 miles LR

    Week 6 14 miles LR

    Week 7 22 miles LR

    Week 8 10 miles LR

    Week 9 RACE

    I'd also swap your faster 5 mile run for a longer 9 or 10 mile run.

    And look at your LSR pace - it is going to be pretty much what your marathon race pace is. If you do that for the 20 milers - you;ll have blown for the marathon itself. I think you need to slow them down more.
  • MillsyMillsy ✭✭✭
    Great advice from Cougie. Couldn't have said it better myself.
  • Week 1 18 miles LR 
    Week 2 15 miles LR 
    Week 3 20 miles LR 
    Week 4 14 miles LR 
    Week 5 20 miles LR 
    Week 6 14 miles LR 
    Week 7 22 miles LR 
    Week 8 10 miles LR 
    Week 9 RACE 


    That seems good. I need to get up to 20 soon. The only objection I would have is to week 7. I don't think I'll gain much from running that distance that close to the race? By all means correct me if I'm wrong. I think I'll strive to run 22miles in week 5.

    I don't think 8:45 min/miles are outside my parameters - which equates to 3hr50?. Bearing in mind I think I'm capable currently of a 1hr45 HM if raced.

  • MillsyMillsy ✭✭✭
    But you don't run your 20 mile training runs at race pace.
  • If you struggle to do a slow 22 - then how will you race 26 ?
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