Polar M430 and A370 heart rate sensors have a problem with dark skin

The company is addressing the issue with a firmware fix

When we reviewed the Polar M430 recently we raised one pretty big issue with the running watch - the heart rate sensor didn't provide readings on dark skin. In fact, I was not able to measure my heart rate with this device even once despite multiple attempts.

We raised the problem with Polar while a reader also got in touch with us to say they had experienced something similar with Polar's A370 fitness tracker. The company has been investigating the issue and has now responded admitting that it has "identified a small firmware issue with the M430 and A370", which has caused its heart rate monitor to struggle providing readings on dark skin. Oh dear.

Read this: Why Fitbit's sensor shake-up is a huge deal

It added that this has affected "a very limited amount of users" and that the issue will be addressed in a firmware update that will be due out in early September. We'll re-test the feature after the update.

This isn't the first time we've heard about wrist-based heart rate monitors struggle to produce readings on darker skin. The Apple Watch and the Xiaomi Mi Band 2 are just two devices that have come under scrutiny from some users in the past.

So why does it happen? Well, part of it is down to the green light-based optical sensors that these wearables rely on to provide heart rate data. As we've discussed in great detail before, skin tone and even tattoos have been known to affect the ability that these sensors have to generate the signal inside of the body it needs to provide HR data.

Is it acceptable that this happens? We're not so sure. While it's certainly good to see Polar is addressing the problem, it does raise more questions about whether the testing of these optical heart rate sensors is carried out on a wider range of people and skin tones before they are available to buy.

Here's hoping it doesn't happen again, but we have a feeling this won't be the last time we're talking about heart rate sensor issues.

Have you had problems with Polar's heart rate sensors? Let us know in the comments.

polar m430 a370 heart rate issues skin colour

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  • genial4pty·

    I had the similar issue and I found a physical solution and emailed them. They could create it and ship out to persons affected.

    Yes you are right they should test on a wider range of persons as they are global so this should never have happen.

    I am so sorry I missed these types of reviews but I think it was google filtering them out as I did search for reviews but only got some.

    The solution I found was to place two small pens on either side of the watch. Apparently once you have darker skin the sensor only works if it does not touch the skin so the pen kept it from touching. Obviously it would not work when running so I asked Polar to create a small platform that one could fit between the watch and their risk. It could even be transparent too but it should not interfere with the light reflecting on the skin for to work.

    I also noticed that if I touch the sensor with my fingers which are lighter as this is my palm it reads my heart rate so I figure it was something to do with the light and the different reaction to darker skin.

    I had the FitBit Surge and that worked great but it was not strong enough or had enough features to last a real hardcore runner So I switched to the Polar M400 but then had issues with the chest monitor falling off even in a race I had which caused me to have to slow down, so the Polar M430 was great news until this happened.

    Depending on how Polar responds I may not publicize this on forums or reviews for persons to be aware before they purchase, I think it is only fear as my Polar M400 was still great and still is so as it is now I wasted $230.

  • genial4pty·

    Hello I found a solution which works for me so just sharing to help others.

    I placed a thin plastic between my skin and the sensor on my wrist and that worked. Unfortunately I am not able to post images here to show exactly how but the aim is to not have the sensor touch the skin so the light can shine through the plastic.

    I have contacted Polar outlining two methods with the last I just mentioned and have not yet heard from them however I will publicize to help other persons know so they can get to use the hand wrist heart rate feature.

    • Katherley·

      Thank you sir. Your solution helped me with a similar problem with my expensive Garmin Fenix 5x Plus. It would not read oHR on my dark skin on. Consistent 24 hour basis. Garmin has not responded to queries either. Reading your post, I placed a 0.19mm round plastic stickon tab (Fix o Moll brand) on the sensor to take the sensor off the skin. It has worked 100% ever since. A $5.00 solution to a big problem.

      Maybe they need to find a software or hardware solution but this the problem in the interim.


  • bjhamltn·

    Due in early September. Does this mean they are now testing to see how well their fix worked? How is it that the A360 worked with dark skin users but these two new devices didn't. When I think of Polar I have to say that lack of diversity comes to mind.

    "a very limited amount of users"

    I guess Polar is not interested in expanding its customer base of non-caucasian users.

  • Bigaapl·

    HasĀ this issue been fixed??