Chest vs Wrist HR monitors?

Hello everyone!
This is my first post here - though I’m reading the forum already for a while - so Hi all :slight_smile:

My question:
Do you have a) personal experience and even more b) references to studies investigating HR measurement with wrist-based devices (e.g. Fitbit Charge) vs. chest-strip devices (e.g. your standard sport Garmin).
I would further like to distinguish between everyday usage (walking) and sport-usage (focused running and sport training).

Are there differences in accuracy? Or other factors that make a difference?

Looking forward to your responses!

Hi Florian! I suppose it all comes down to your goal for said tracker. Each does something different, but your end goal for measuring heart rate will depend on which you use.

The wrist based devices tend to measure on an average that will give you a close HR, but because it’s averaging, you don’t get a true beat to beat measurement. This is the advantage to the chest strap being more ECG based as it can measure every beat instead of averaging the perceived pulse. I’m not familiar with the details of the Garmin’s, but I know Polar’s H7 monitor has a VERY high sample rate upwards of 2500 samples per second if I remember correctly. This is actually higher than some medical grade devices (sample rate). This gives you a superior overall HR, and allows for measurements of HRV/autonomic function because you have a true R to R value to measure. The averaging function of the wrist models can’t do that at this time.

If you’re looking to track your HR throughout the day and a general sense of your HR for your workouts, the wrist-based devices will work fine. If you’re looking for more accurate measurements and examining your HRV function, you’re looking at a chest strap. Hope that helps.


Thank you Frederick.

Hi Florian,

This is my first post to the forum. I have been investigating this myself and just purchased and Apple Watch S2 for the purpose of tracking fitness via the heart rate.

In my quest I learnt the following things:

  • Optical heart rate monitors depend on the ability of light to penetrate the skin.
  • Things that can block the light resulting in lower accuracy: Hair, darker skin, tattoos, sweat, loose contact. So hairy men with accuracy problems should shave their wrists, sweat should be wiped, the band should be firmly tightened etc.
  • Optical HRM lose accuracy for higher heart rates (e.g. beyond 150bpm or so)
  • Optical HRMs operate at a lag to your actual heart rate. So if you pick up the pace and go from 100bpm to 120bpm for example, the optical HRM will take a while to catch up relative to the chest strap which is virtually instantaneous.

So if you are measuring steady low heart rate exercise like going for a casual bike ride, where you are not constantly speeding up and slowing down, the optical HRM will do a good job.

If you are doing interval training (deliberately oscillating between low heart rates and high heart rates) at high intensity and you are very sweaty and your hands are moving around a lot, the optical heart rate will do a lesser job.

My solution was to get a watch that has a good optical HRM but can also pair with a chest strap as I do both types of exercise. My options included things like the Polar M200, the Vivoactive HR, the Apple Watch S2. I ruled out things like the Samsung watches, Fitbits etc as they can’t pair with external HRMs.

I bought the Apple Watch as I preferred its looks to the M200 and the Vivoactive HR and I figured I would be more likely to wear it all the time. Between the Polar M200 and the Garmin Vivoactive HR I would have chosen the M200 since it plays better with Apple Health and Google Fit and therefore I could leave the watch behind and allow the phone to track steps and then combine both data sets.

So I have had the Apple Watch for a couple of days. I have exercised using the Apple optical HRM for cycling and compared it with a chest strap paired to an old Garmin watch. Actually I found the average HR captured by Apple’s optical HRM to be exactly spot on with the chest strap. I could see the lag, but to be honest, it was much better than I was expecting, so for tracking calories it is perfect (my main motivation). My HR went up to around 140. I have yet to try a proper exercise session with higher more variable heart rates. My HR when jogging goes up to 170-180bpm and I get very sweaty so I am expecting I will need the chest strap.

Below is a good video demonstrating a Polar M200 via optical HRM, a cheap watch with optical HRM and a chest strap via a Garmin and shows the relative accuracy.


Update: I just did a 10 minute treadmill run comparing the Garmin watch with chest strap and the Apple Watch S2 using the optical HRM. I oscillated between 130 and 170 bpm according to Garmin with chest strap. The average heart rate as calculated by Apple Watch with optical HRM was identical to the Garmin at 145bpm. Basically the optical HRM works very well.


Hi quicklime an thanks for the very nice read!
I think your solution to have a wrist-sensor for almost everything and then a chest-strap for these high intense sport session sounds most suitable for my situation.

Have you encountered any academic work on the comparison between these two types of sensors?

Enjoy your apple watch!

I have had 4 chest HR monitors over the years. Each has kept a running average of heart beats unlike an EKG. Several have averaged the last 10 heart beats. I don’t know what the others averaged.

Hi Florian,

This mentioned study compares optical HRM versus EKG:


Hi Florian,

I am an enthusiast cyclist and data geek. Many endurance athletes (runners, swimmers, cyclists, duo and tri) athletes collect and train with a lot of data. All pros (as I understand it) train with data – HR is one of the measures – there are lots of others.

In fact, endurance athletes use mathematical models like the TRIMP and Coggan models to guide their training.

These models incoporate data from sensors to estimate Fitness, Effort, impact of different workouts etc. As you can imagine a lot of attention goes into the devices.

This is a long introduction to set the stage for my reference to dcrainmaker’s website

DC Rainmaker (Ray) is the go to guy for all us endurance sport amateurs. He does lots of reviews of training devices and is the pretty much the trusted source. For example here is his review of the Mio Link complete with graphs and stuff.

Over the past years I’ve had HRM straps from Polar, Wahoo and Garmin. Based on Ray’s work I current use a Scosche RHYTHM optical sensor

You can see one the results of the accuracy testing here

His summary “Overall, the accuracy over the vast majority of the the time is very solid. There appears to be two fringe cases where it struggled, but in each of those cases it didn’t struggle every time. Meaning that I both crossed steel grates more than once without issue, and I crossed cobbles countless times without issue. It’s also of note that I didn’t see any issues with rough roads, which is also common in Paris as oftentimes the road is just cobbles poorly paved over.”

"Overall the RHYTHM+ performs very well on a day to day basis. While at first I was hesitant about wearing it in a non-wrist location, I actually grew to not mind it on my lower arm. And once I moved it to my upper arm, I loved that it was completely out of the way and ‘invisible’.

No doubt the optical sensor market is really just getting heated up. There are a slew of recently introduced products out there – some of them doing well and some of them are struggling. "

Hope this helps and good luck for your search.

(Oh by the way you want R-R recording if you are interested in HRV)

@quicklime Nice report and study. I wear an Apple watch but if I care about the workout I record with a Schosche RHYTHM which has dual channel BT and ANT. Garmin Connect is my exercise data “hub”.

Thanks for sharing!

@lotusflyer Thanks for the great post. I will read your recommendations!

Do you personally think (as an athlete) that optical HR sensors will replace the chest sensors in the future?


Well speaking as an athlete wannabe if Ray (DC Rainmaker) is using an optical sensor then I think optical sensors are well on their way.

As for the “big boys” – the pros – I don’t know – they will go to great lengths to get the smallest advantage. However in the cycling world – power – watts – is the big thing to measure and that is the focus. Pros use Power Meters (SRM) that cost many times what mine does (Stages).

BTW I meant to mention the Optical wrist sensor on my Garmin Vivoactive HR does not work at all for me – in my experience its not the technology so much as the way it is implemented. Here is a detailed review

Sorry to say but I think you might find different devices perform differently for different people. That said I love my rhythm. Its super comfortable, has decent battery life and seems pretty accurate. With both BT and ANT support you can use it with phones, Garmin devices and even my Mac :slight_smile: