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My heart rate zones are incorrect and inaccurate for the effort I am putting into my running

MTS80
5 months ago

When on an 'Easy Run' which should be in Z2 according to my Training Plan, my Garmin Fenix 7 is showing that I am in Z3 for the majority and sometimes Z4. My so called Z2 runs are easy and I could quite easily hold a conversation (and I am often signing to myself as I jog along). 

Zones are currently set at:

Z1: 89 - 106 BPM

Z2: 107 - 124 BPM

Z3: 125 - 141 BPM

Z4: 142 - 159 BPM

Z5: 159 and above BPM

My max BPM is 178 according to Garmin although it should be 176 (220 BPM - 44 for my age). I have customized my HR zones to what I think is more reasonable according to the effort I am putting it but I think this is almost 'cheating' Garmin and is not giving me a realistic and accurate 'Training Status'  and 'Training Load', which is what I need in order to improve my overall fitness and performance.  

My target race pace for my next Half Marathon is approximately 7:40 mins per mile. so, if easy runs are supposed to be 90 seconds slower that would put me at 9:10 mins per mile (according to various articles available online). A recent run at 9:10 min per mile average pace which I would definitely class as easy has me running in Z4!

I recently bought the Garmin HRM ProPlus to try and get more accurate HR zones as I was under the impression after it been worn for a number of activities it will automatically re calculate the zones for me. Can anyone confirm if this is correct? I have only worn it for 3 or 4 short runs so far and nothing seems to have changed, do I just need to be patient and wait for it to auto calculate and update my zones? 

For added context, my 1/2 marathon PB is 1:44.06 and 10k is 45.57 and these were both set in September 2024. 

Any help or advice would be much appreciated. 

  • 0 5 months ago

    The 220 - age formula may work for some people, but not always. I'm 62 years old, with the formula putting my max at 158. So far in 2025 I've reached 180 or more on five occasions and can comfortably average 160+ for an hour or more. You need to establish YOUR true max and a formula won't cut it. I do it with a balls out effort after a good warm up. 

    As for the strap estimating your max - it's not the strap that makes the estimate - it's the device it's connected to, if it has that function. In my experience it might get you in a better ballpark than the formula, but it won't be as exact as following a proper max HR test protocol.

    My Epix has my max estimated as 191 right now. That's pretty close, maybe even spot on, although I haven't tested the limit for many months, but it's way, way better than that formula (for me).

  • 0 5 months ago in reply to eezytiger

    Thanks for your response. When I have ran with a bit more effort, usually towards the end of a long run, I have had notification that my Max HR has changed but this is usually just a very slight fluctuation up or down.

    I think I will follow your advise and have a warm up tonight and then run all out for as long as I can to see what max HR it gives me. 

  • 0 5 months ago in reply to MTS80

    Try to finish your run on a climb. It will help push the heart to the max before your legs run out of speed. GrinningAlso, don't drag out your fast finish too much. Maybe a progressive pace increase with max effort saved for  the final 400m. You don't want to tire before you get to the main event.

  • 0 5 months ago

    I would suggest to set your HR zones in %LTHR not to HRMax.
    LTHR is much more reliable factor which might change with your fitness level.

  • 0 5 months ago

    If you have an HRM, there is a lactate threshold test built in the Fenix 7 that you can utilize. Then set your zones accordingly, based on %LTHR.

    Or you take your last 4km of that 10k - or 3km of a 5k where you put much effort in. Take the average heart rate in those 4 or 3km and it will be close to your lactate threshold.

    If you want to fine tune the zones you can do it like in this article: www.suunto.com/.../

  • 0 5 months ago in reply to eezytiger

    Just ran a steady mile warm up, gradually increasing pace then went full at it! Maximum HR was.... 176bpm ThinkingPunch tone1
    Rofl. I think maybe I might have peaked too early so I'll try again tomorrow, pretty sure I've got more in the tank!

  • 0 5 months ago in reply to Adam-1972

    I actually tried that tonight, was wondering what the best option would be so thanks for suggesting and making helping me decide.

  • 0 5 months ago in reply to 2b2bff

    Thanks for this, I'll look at doing a LT test tomorrow. Really interesting article as well, I'll follow that advice at the weekend Thumbsup tone1 

  • 0 5 months ago in reply to MTS80

    There is no longer LTHR test build in, it was removed by Garmin couple SW versions ago.
    Now watch will estimate your LTHR on each run, of course if something will change.

  • 0 5 months ago in reply to Adam-1972

    I realized this after much searching last night! Rofl. I have found that my LTHR is 162BPM. I looked at various websites last night with LTHR calculators that show you what your HR zones should in relation to my LT. Although there are some slight deviations, the general consensus seems to be:

    Z1: upto 120 (ish) BPM

    Z2: upto 140 (ish) BPM

    Z3: upto 150 (ish) BPM

    Z4: upto 160 (ish) BPM

    Z5: 165 BPM and above

    Whilst not exact figures due to the various articles that I looked at, it does show that the range for Z2 should be from around 120BPm to 140BPM. This would make sense to me as my 'Easy Runs' average at 140 ish BPM but Garmin thinks that I am running in Z3. 

    My HR zones are now set and based on %LTHR and are as follows:

    Z1: 65% - 79%

    Z2: 80% - 89% **** (manually calculated to 130 - 144BPM) Thumbsup

    Z3: 89% - 94%

    Z4: 95% - 99%

    Z5: 100% to 109%

    So as long as my Garmin follows these zones on my run tonight, I should a much more accurate reading.