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    HR sensor accuracy

    Scheduled Pinned Locked Moved Suunto Race
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    • Arnaud LclrA Offline
      Arnaud Lclr Bronze Member @David l
      last edited by

      @David-l Thanks @Brad_Olwin , and I don’t agree with you at all @David-l .

      This study does have the capacity to easily illustrate the difference between a competition medical device, a heart rate belt recognised as the best on the market (H10) and an optical reader, the Fenix 6.

      It’s much more scientific than a ‘youtuber’ review like DC Rainmaker, which does interesting practical tests but with a scientific veneer that makes the non-scientist think it’s very scientific and which is in any case incapable of remaining impartial !

      I don’t think the point of talking about this article is to excuse the inaccurate measurement of Suunto’s optical readers, or those of any other brand.
      If the article can make those on this forum understand that if you want the most reliable measurement possible to be able to interpret all the Suunto indicators, you need the most reliable measurement and that therefore: sport = heart rate belt, that’s already great…

      And I think it’s time for brands to stop claiming too much about optical readers 😉
      Or maybe for Suunto to come out with a heart rate monitor that’s even more accurate than the Polar H10.

      After 8 years with Garmin and several watches in different ranges, I switched to Suunto in 2023, with the Race.

      David lD D 2 Replies Last reply Reply Quote 2
      • David lD Offline
        David l @Arnaud Lclr
        last edited by

        @Arnaud-Lclr said in HR sensor accuracy:

        @David-l Thanks @Brad_Olwin , and I don’t agree with you at all @David-l .

        This study does have the capacity to easily illustrate the difference between a competition medical device, a heart rate belt recognised as the best on the market (H10) and an optical reader, the Fenix 6.

        It’s much more scientific than a ‘youtuber’ review like DC Rainmaker, which does interesting practical tests but with a scientific veneer that makes the non-scientist think it’s very scientific and which is in any case incapable of remaining impartial !

        I don’t think the point of talking about this article is to excuse the inaccurate measurement of Suunto’s optical readers, or those of any other brand.
        If the article can make those on this forum understand that if you want the most reliable measurement possible to be able to interpret all the Suunto indicators, you need the most reliable measurement and that therefore: sport = heart rate belt, that’s already great…

        And I think it’s time for brands to stop claiming too much about optical readers 😉
        Or maybe for Suunto to come out with a heart rate monitor that’s even more accurate than the Polar H10.

        Absolutely agree with this point! Just use OHR as a guide 👍

        1 Reply Last reply Reply Quote 0
        • D Offline
          duffman19 @Arnaud Lclr
          last edited by

          @Arnaud-Lclr I’m not sure anyone would consider the5krunner more reliable than someone like @dcrainmaker. Yes, the source of the graphs appears to be from a scientific paper, but there is no direct access to it and little to no context given. If you read the comments, it appears the5krunner didn’t even realize the results were taken while exercising. I think t5k went back and edited the (very short) article to clarify this. He/they even added that "we can’t infer the performance of RR recording at lower levels from thse [sic] results.”

          I agree with @David-l that we’re all well aware that OHR, specifically at the wrist, is less reliable than an electrical chest monitor. No news here.

          Vertical Ti

          Jean LamyJ Brad_OlwinB 2 Replies Last reply Reply Quote 1
          • Jean LamyJ Offline
            Jean Lamy @duffman19
            last edited by

            Hi guys,

            Very interesting readings here. Helps a bit understand my “bad HR sensor” impression since wearing the Race (titanium).

            Here are 2 photos taken from the same exercice (small fitness) wearing Race versus good old Suunto 5.

            I think I’ll try moving the watch up + resetting and I’ll see.

            HR sensor is not 100% a major issue for me but when you put a lot of money on a watch that is supposed to work (and be better than the previous one) you expect something better.

            PXL_20240112_163115177.jpg PXL_20240112_163110388.jpg

            1 Reply Last reply Reply Quote 0
            • Brad_OlwinB Offline
              Brad_Olwin Moderator @duffman19
              last edited by

              @duffman19 I can upload the manuscript if you wish. I have access.

              Vector/T6c/Ambit 3 Peak/S5 Copper/S3/S7 Ti/S9 baro Ti/S9P Ti/S9PP Ti/Vertical Ti/Race Ti/RaceS/Ocean/Wing

              1 Reply Last reply Reply Quote 0
              • Kurt68K Offline
                Kurt68
                last edited by

                Garmin with chest strap suunto on the wrist no major abnormalities. 🤷‍♂️

                7f2ed559-3800-4790-bd78-bc0b38d00322-image.jpeg

                1 Reply Last reply Reply Quote 5
                • A Offline
                  AnnaBi
                  last edited by

                  Have my Suunto Peak Pro 9 since January 2024. Almost ever since the beginning, once every couple of workouts (very randomly) I have been experiencing horrible HR sensor accuracy. Let’s say I go for a run - I tend to have very high HR during cardio workouts, so my HR will usually be around 160 or more. Then, all of the sudden, my Suunto will start showing something completely false like 90 or 100. It makes the watch absolutely unreliable.

                  Below is my Strava screenshot from 25 km nordic skiing competition I participated in recently - it was very heavy workout for me, as you can see from the first couple of kilometeres… and then the HR sensor went down to 80 or 90. sn’t HR measurement one of most important things that a sport watch should do?

                  It happens repeatedly, randomly and makes the HR measurement, which is a really crucial feature for me, completely unreliable.

                  I have sent the watch to Suunto service - they said that they ran all the tests and everything works fine, so I should consider buying the Suunto chest strap (!!).

                  My boyfriend has a Garmin of comparable class and the HR works fine for him. I am extremely disappointed with both the product and the service - this is certainly not the quality I had expected from the brand Suunto. I am definitely not getting another Suunto watch ever again.

                  Screenshot_20250316-214833.png

                  ? 1 Reply Last reply Reply Quote 0
                  • ? Offline
                    A Former User @AnnaBi
                    last edited by

                    @AnnaBi If HR is crucial, you need to use a chest strap. Wrist-based monitoring is garbage for sports, regardless of the brand. (It may seem to work at times, but the values are inaccurate, even if some models appear to perform better than others). The wrist-based heart rate sensor is simply not suited for sports but rather for daily tracking.

                    2 1 Reply Last reply Reply Quote 1
                    • 2 Offline
                      2b2bff @Guest
                      last edited by

                      @Ghost as this is true for Suunto, it isn’t for all watches on all brands.

                      My Epix Pro has really great HR accuracy, unless the software bug hits that prevents it from being. There is almost nothing to gain with a chest strap. I could show you examples, as Garmin records both external and wrist heart rate in the FIT file.

                      Suunto Race S
                      Garmin Epix Pro

                      SODIUMS ? 2 Replies Last reply Reply Quote 0
                      • SODIUMS Offline
                        SODIUM @2b2bff
                        last edited by

                        @2b2bff I think the reality is that the Optical heart rate sensor on watches in the world is not accurate enough to be comparable to a chest strap with a medical ECG cable.

                        2 1 Reply Last reply Reply Quote 0
                        • 2 Offline
                          2b2bff @SODIUM
                          last edited by

                          @SODIUM identical - no. Comparable and perfectly usable if you don’t need the last beat? Yes.
                          As an example: Threshold Run - Epix Pro against HRM-DUAL.

                          7d8aeacb-fe87-484c-8cdd-195d2bd217ce-image.png

                          Suunto Race S
                          Garmin Epix Pro

                          M 1 Reply Last reply Reply Quote 1
                          • M Offline
                            Matúš Bronze Member @2b2bff
                            last edited by

                            @2b2bff said in HR sensor accuracy:

                            @SODIUM identical - no. Comparable and perfectly usable if you don’t need the last beat? Yes.
                            As an example: Threshold Run - Epix Pro against HRM-DUAL.

                            7d8aeacb-fe87-484c-8cdd-195d2bd217ce-image.png

                            Activity type?

                            Suunto 9 Peak Pro Titanium Slate
                            Suunto Spartan Sport

                            #swatt

                            2 1 Reply Last reply Reply Quote 0
                            • 2 Offline
                              2b2bff @Matúš
                              last edited by

                              @Matúš Running, as I said…

                              Suunto Race S
                              Garmin Epix Pro

                              M 1 Reply Last reply Reply Quote 0
                              • W Offline
                                wakarimasen Silver Members
                                last edited by wakarimasen

                                I think the fact is that OHR is not reliable for all people and in all circumstances, whereas a chest strap is. One person could use a Garmin with great results and yet be no good with a Suunto or Polar. Someone else could have completely opposite results. The measurement method depends on too many things to be entirely accurate for all people, all of the time for all activities.

                                For me, Suunto works well, but I still use a chest strap for running and gym activities.

                                If accuracy matters - and it seems to for most people - buy a chest strap and stop worrying. 🙂

                                Suunto Race Titanium
                                Suunto Ambit3 Peak
                                Polar H10
                                Polar OH1

                                1 Reply Last reply Reply Quote 0
                                • M Offline
                                  Matúš Bronze Member @2b2bff
                                  last edited by

                                  @2b2bff, sorry, I’ve missed the “Threshold Run” tag.✌ Is this true even if you’re using poles (if you have ever tried)?

                                  Suunto 9 Peak Pro Titanium Slate
                                  Suunto Spartan Sport

                                  #swatt

                                  1 Reply Last reply Reply Quote 0
                                  • ? Offline
                                    A Former User @2b2bff
                                    last edited by

                                    @2b2bff I disagree. This has absolutely nothing to do with Garmin or the EPIX. You’re lucky because your wrist perfectly fits this model. You’re lucky because your running form is compatible, and you’re lucky because your arm movement isn’t excessive enough to disrupt the measurement.

                                    I invite you to South America, deep in the Amazonian forest, where you have to run through thick brush, cross muddy streams, and then we can talk again about the reliability of wrist-based heart rate measurement. For some individuals, it may work in specific conditions, but certainly not in multisport activities—especially not during intense efforts.

                                    On the other hand, a chest strap provides accurate heart rate measurement in any situation and for all body types, regardless of size, age, or weight. That’s why I’ve explained that wrist-based heart rate tracking is not reliable. It doesn’t work consistently, no matter the brand or model, with only a few morphological exceptions.

                                    2 1 Reply Last reply Reply Quote 1
                                    • dankcushionsD Offline
                                      dankcushions
                                      last edited by dankcushions

                                      it’s pretty extensively documented that suunto race (original) was worse OHR than competitors in the same scenarios. both desfit and dc rainmaker reached this conclusion. as it has the same gen sensor as the 9PP, you can assume OP has the same issues.

                                      the race s has a upgraded sensor with better results. if the race (original) and 9PP had decent OHR they wouldn’t have updated the sensor. yes, OHR is limited and never as good as a chest strap, but that doesn’t stop there being bad OHR sensors. stop gaslighting OP…

                                      ? 1 Reply Last reply Reply Quote 0
                                      • 2 Offline
                                        2b2bff @Guest
                                        last edited by

                                        @Ghost agree to disagree.

                                        I didn’t say wrist heart rate is perfect and a chest strap is unneeded und all circumstances. I’m just a bit allergic to the “wrist heart rate will always lie to you and you need a chest strap for anything that is more than a guess” approach. Simply because it is not true. If you are a casual street runner and don’t aim for perfection wrist heart rate might be all you need - if the values suit you.

                                        Sure chest strep will always be more accurate, but also it is more of a hassle when you add a vest or run for longer periods. And it is another device that could fail.

                                        TBH if I ever happen to run in the jungle, I don’t think I wouldn’t care about HR that much… 😉

                                        Suunto Race S
                                        Garmin Epix Pro

                                        ? 1 Reply Last reply Reply Quote 0
                                        • ? Offline
                                          A Former User @2b2bff
                                          last edited by

                                          @2b2bff Sure thing. But @AnnaBi said HR was crucial, so I responded: if it is crucial, it shouldn’t be based on casual, approximate data—it should be measured with a chest strap. And I always wear one during sports, to the point that I don’t even notice it anymore, enjoying ZoneSense, running in the jungle or doing jump rope.

                                          1 Reply Last reply Reply Quote 2
                                          • ? Offline
                                            A Former User @dankcushions
                                            last edited by

                                            @dankcushions It’s well-documented that wrist-based optical heart rate (OHR) has limitations, and yes, some sensors perform worse than others. The Suunto Race (original) using the same gen sensor as the 9PP did get criticism for its OHR accuracy, and the Race S upgrading the sensor suggests Suunto recognized the need for improvement. That said, OHR performance also depends on individual factors like wrist physiology, fit, and activity type.

                                            No one’s denying that bad OHR sensors exist, but calling it gaslighting is a stretch. If OP needs reliability, a chest strap remains the best option—no wrist sensor will consistently match it.

                                            dankcushionsD 1 Reply Last reply Reply Quote 2
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