Sunday, 17 February 2013

Heart Rates. What a confusing thing they are

Right I've been worried about how high my heart rate (HR) goes when I'm running.

Now the question is should I be worried or is it just me. Let me explain.

According to t'internet your max HR can be worked out using the formula of 220bpm (beats per minute) minus your age.

For me this would equate to 189bpm given I am 31 years young.

Also about t'internet are estimations on what bpm your HR should be.

Using the following page. my HR zones should be as below.

Zone 1 (40-52%) - 108 - 124 bpm
which is described as healthy heart and could be apparently achieved by walking briskly

Zone 2 (52 - 64%) - 124 - 141 bpm
which is described as easy and could apparently be achieved by jogging

Zone 3 (64 - 76%) - 141 - 157 bpm
which is described as aerobic and could apparently be achieved by running

Zone 4 (76 - 88%) - 157 - 173 bpm
which is described as anaerobic threshold and could apparently be achieved by going hard

Zone 5 (88 - 100%) - 173 - 190 bpm
which is described as VO2 max and could apparently be achieved by going all out

Now using the above data when I go for my 10km runs I would expect my HR to be mostly be between 124 and 157 bpm which are the zones which cover "jogging" and "running". However if we compare my last three long runs of 10k using the data from my Garmin my HR's have been as follows.

17/02/13 - Distance 7.02 miles in 01:19:31, where my average HR was 161bpm and my maximum HR was 174bpm

10/02/13 - Distance 6.22 miles in 01:07:57, where my average HR was 155bpm and my maximum HR was 173bpm

02/02/13 - Distance 6.58 miles in 01:10:56, where my average HR was 163bpm and my maximum HR was 176bpm

As you can see the above puts me on the boundary between zones 3 and 4, which should mean I am being anaerobic. Now from my understanding anaerobic exercise should only be able to be maintained for a duration of about 2 minutes comfortably.

However I can maintain a "zone 4" HR for a period of longer than 2 minutes. I did maintain a "zone 4" HR for period of over 23 minutes today.

Thus the only conclusion I can make is that my zones are not as estimated by various sources on t'internet. I believe that my trigger HR between aerobic and anaerobic is 170bpm ish. I can carry on running for periods of 20+ minutes as long as my HR does not breach my 170bpm threshold. This makes estimating my other zones extremely difficult.

Joe Friel agrees on his blog ( with my estimations above and his esteemed colleague John Post MD states in this blog post that

"1)     No two of us are the same.
2)     No two of us fit the exact same formula/parameters relating heart rate to training."

Now if I throw in the bike things become even more complicated. I have no idea what my zones on the bike are which means that training in zones when running or cycling is difficult for me. I just have to learn to listen to my body and what it tells me. I know when I need to walk to lower my HR. I'm even debating ditching the HR monitor strap and

Who knew when I took up this triathlon lark that I would get so confused and involved with training and HR zones.

Sorry for the boring post but this whole HR mumbo jumbo has been on my mind for a few months. Remember I am doing this for charity, if you feel like sponsoring me you can do by going to

Thanks for reading.


1 comment:

  1. Everything you've got off the internet is a rule of thumb and not accurate or personal to you. If you want exact heart rates personalised to you then you will need to attend a sports science clinic for testing. That said though, stick with the rules of thumb for now as they pretty much work for the majority.

    I've taken my HR Zones from Don Fink's 'Be Iron Fit'. I did start to use Friel's system which is different, but I found his whole approach a touch complicated for a beginner like myself.

    Basically, MHR = 220 - age
    Zone 1: 65% - 74%
    Zone 2: 75% - 85%
    Zone 3: 86% - 89%
    Zone 4: 90% - 95%

    These zones work well for running, however since running and cycling impact he body differently, subtract a further 5% from you MHR before working out your cycling HR zones. (You can use the Garmin Connect website to input your HR Zones and transfer them to your watch)

    For endurance training you want to concentrate your efforts in Zone 2, ie. between 75-85% of your MHR.
    Zone 2 is described as a conversational pace. This may seem like an easy pace and you may feel you are not getting the full benefit from your exercise but stick with it as it is building your base fitness and endurance. After all it is aerobic endurance you want for the IM1

    Different activities effect the body and HR to a greater or lesser extent. Running is more impactive than cycling so results in a higher heart rate for the effort. You need to back off the pace while running so your HR does not go sky high. Set your HR alerts on the 910XT for Z2 and slow your pace down so that you stay in the zone. When I started running, my HR used to go through the roof almost instantly at a pace of 7 min/km. I started training with HR zones and now I can now hold zone 2 at a faster pace than used to send my HR sky-rocketing. If I attempt to go even a little faster, my heart rate soon reaches zone 4 or 5!
    You will find that running becomes easier as your base fitness improves and you'll be able to pick up the pace again.

    At the moment you sound like you are going 100%, hitting zone 4 and staying there. All this is doing is increasing you lactate threshold and anaerobic endurance, it's not doing anything to increase your aerobic fitness, which is what you need for the IM. You maybe able to run short distances using this approach (I was in Zones 4 & 5 for most of the London Triathlon) but try it during and IM and you'll bonk for sure and a DNF will be the result.

    Training in Zones 4 and 5 will help increase your VO2 Max, speed and anaerobic fitness, but continued training in these zones will more than likely result in injury. Everything I've read suggests not to introduce zone 4/5 training until the later stages of your training and even then, limit it to a max of 10% of your training time.

    My advice would be to re-calculate your HR zones to the values above and then program them into your watch. Set the HR alert for zone 2 and concentrate on staying in your zone. Don't worry about speed or distance as these will most definitely reduce when you first change the emphasis of your sessions to HR zones but they will build again and you will feel the benefit come race day!

    I hope this all makes some sort of sense.

    Good luck,