How accurate are wrist-based HR monitors?


On the bike I use a Tickr HR strap and wear a Garmin Vivoactive 3 ‘watch’.

Today on the trainer doing thesthold work the strap said 176 while the Garmin optical said 88, and never rose above 116. :rofl: The optical HR figures for me on the bike are just nonsense, and so I make no use of them whatsoever.

When running, the Garmin optical has been better, but only up to a point, frequently under-reading, sometimes dramatically. Sat around, the figures from the Garmin optical seem correct.

But for my partner, the same Garmin optical wrist-based seems to work fine for her when running, every time.


My Vivoactive 3 tracks my HR with less obvious errors than a Wahoo Tickr chest strap, even up to a HR of 201. But, my skin color is quite light, I have low body fat, little hair and visible veins. Overall, I prefer VA3 over Wahoo Tickr.


My WHOOP band tracks perfectly with my chest strap both on and off the bike. I’ve been very happy with the performance, thus far! As an alternative, they also have a bicep band for their sensor. Totally worth checking out - for multiple reasons!


That’s funny, because your physical characteristics describes me to a tee!

Yet totally opposite results :laughing:


My experience with Garman FR235 bulleted for easy consumption… I am somewhat fair skinned with not much arm hair, low body fat:

  • Not accurate enough for consistent Hr based zone training in running or cycling. I would use a strap (love my Wahoo Tickr) for this.
  • Pretty good for resting HR.
  • Accurate enough for monitoring HR as a secondary metric when running. I use pace or power as primary effort metrics when running. I don’t wear it when cycling very much anymore.
  • Accurate enough for some pacing when running once you’re dialed in to RPE with pace or power. I didn’t wear my HR strap for my recent 70.3 A race (who does)? The run featured about 6 miles of sand running where Stryd power wasn’t useable and pace wasn’t a consistent metric due to the inconsistent pack of the sand. Therefore, HR and RPE were my best bets. I had the 235 on my wrist fairly snug, and it did a good enough job tracking my HR to give me a good idea of my pacing effort for those sand sections.

Bottom line: my 235 is accurate enough for occasional HR use, HR tracking for info, or as a backup, and probably accurate enough for most people’s exercise tracking, but I would recommend a HR strap to any serious racer who wants to use HR as a primary training metric or training zone basis.


I have found the Apple Watch Series 4 optical heart rate tracks very well against my Wahoo TickrX strap when I’m warm - on the indoor trainer it’s an almost perfect match - with perhaps up to 5s of lag against the HR strap.

But outdoors, when it’s cold - or more importantly my hands are cold it’s useless. I was hoping it would replace a HR strap for running, but unfortunately not - at least while the temperatures are lower (<5C).

I do get cold hands, and I don’t wear gloves for running. But often the HR will just stick at some random value for some time. I’ve tried everything and I just can’t rely on it. So back to HR strap for me - but if you’re running in warmer climates, or perhaps you have better circulation you’ll probably find it just fine. Outside cycling’s ok since I tend to be dressed up warmer and with gloves.


My VivoSmart 4 optical works well throughout the day (compared w chest strap & Edge) but during a trainer workout it’s WAY off, usually 30-50bpm lower than the chest strap is reporting.

I’ve tried moving it around, flipping it to inside of wrist, etc but have been told that’s just a limitation of optical :man_shrugging: Not really a big deal as I still use a strap during actual workouts but it’d be nice to see the accuracy increase.


I noticed that when I have my VivoSmart 4 record an activity during the actual workout the accuracy inproves dramatically. It seems that the sampling of data is increased when in an activity. It is still a bit off and much slower to react to changes off course, but this is indeed a limitation of an optical HR sensor.


Like many here, I was very skeptical at first but I end up moving away from a Garmin watch to an apple watch. I have compared my Apple watch with my Heart Rate Strap during a workout, apple watch seems to be pretty accurate


So, I just did Dade +1 and my Garmin Fenix 5 watch gave me

and my chest monitor gave me

So I’m happy that the Fenix is as usefully accurate as the chest monitor.


I’ve had the Garmin forerunner 935 for over a year now. The heart rate was so inaccurate initially that I emailed Garmin and they sent another one. My chest strap would read 150 and my watch would go as low as 38bpm!!! Unfortunately, the second watch was no different. After being in contact with Garmin numerous times they basically said that the sensor is racist :joy: jk! Buuuuuuut that it doesn’t respond as well to skin with low melatonin (ie. this white girl), which is even funnier because I’m sooooooo pale where my watch goes.

I got over it pretty quickly, and find it amusing jowadays when I’m dying on the trainer and my watch says 55bpm, ha! It does appear to be accurate during general gym weight lifting and every day activities such as walks, sleeping, chasing the dog around. It just doesn’t work for me with higher intensity work (140-200bpm), whether I’m sweating or not, or if it’s cycling or other high intensity workouts.


In my experiences it seems accurate enough, it just takes a while for it to reach the correct level. Especially in intervals.

For example a 3min interval:
Power is instant, chest heart rate stabilizes in around 30seconds. Wrist based takes longer.

Those are based on my personal experiences.

In normal everyday use it seems ok. Tested my Fenix 5 vs a pulseoximetry device, heartrate was the same on both.


That’s consistent with dcrainmaker’s findings who sang the praises of the Apple Watch 4’s heart rate sensor.