Polar OH1 Review (2019 Update) | Optical HR Sensor, Arm-Worn

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Polar OH1 Review

This Polar OH1 Review (2019 Update) will look in detail at Polar’s first arm-worn optical heart rate monitor.


When the OH1 was first announced I was excited.

As it’s ‘only’ a heart rate monitor this will be a fairly short, but detailed review.

In my opinion, Polar have pressed quite a few tasty sports buttons with the OH1, it should sell well for a variety of sports uses which I have previously covered in more detail here (link to: and here (link to:

Don’t worry. I’m still excited.


It’s a Bluetooth SMART optical Heart Rate (HR) monitor (oHRM) intended to be worn on the arm.

You can pair it with apps and sports watches as you would do any other Bluetooth SMART heart rate monitor. There are many apps and lots of sports watches that will be compatible.


It’s waterproof and it can record and store (cache) HR data to be retrieved later. Initially, only the Polar FLOW app can retrieve this cached data.

The downside is that IT IS NOT ANT+ compatible and cannot be used with some Garmin-compatible sports devices BUT new high-end sports devices from Garmin such as the Fenix 5 and Edge 1030, are starting to support Bluetooth SMART.

The OH1 is similar to the Scosche RHYTHM+ product (Reviewed, link to: but the OH1 caches data, is waterproof and has a superior battery life. The only reason to buy the SCOSCHE would be the ANT+ connection – favourable review permitting, of course.


You can use this device in one of three ways:

  1. As a Bluetooth heart rate monitor, just as you would with a chest strap….but on your arm;
  2. As a CACHING heart rate monitor linking and syncing later ONLY to Polar FLOW; or
  3. Those two ways simultaneously, effectively creating two separate, potentially identical, workouts.


Polar’s initial marketing seems to be focussing on ‘women doing gym classes‘. That’s probably a relatively large market but there are also many other sports markets for the OH1 including ‘men doing Monday night soccer/football‘. Gender stereotyping aside, it is great for sports that require: a safe, comfortable wear-position; a separation of the recording device from the sensor; and/or waterproofing. 18 months after release and I still use my OH1 as one source of HR when testing new sports watches.

So that should at least cover these quite nicely: swimming; open water swimming; team sports; gym classes; any regular sport where you just don’t want to wear a chest strap; and 24×7 HR tracking.

*IF* it’s accurate then many people could switch to it.

Let’s not get ahead of ourselves. The accuracy stats will follow further below, so let’s start off this Polar OH1 Review with a bit more detail on the OH1 itself.


I’ll keep this simple. You get a box; the strap; the sensor; a charging cradle; and, of course, lots of bits of paper that you will never, ever read.


The circular pod has all the clever stuff inside it. The strap just holds the pod in place against the skin on the arm (or wherever you put it).

To charge the OH1, the proprietary cradle is required. That cradle will plug into any standard USB port – for example in a wall socket port or in a computer. When mounted into horizontal computer ports it might be tricky to use adjacent ports and vertical ports are better – as shown below.

Either way, you could buy a £/$/Eu2.00 USB extension cable and leave it to dangle in lots of exciting places.


The stated battery life of 12 hours is approximately correct. I have got somewhere between 11.5 and 12 hours of mixed broadcasting-only and broadcasting+caching usage on a single, full charge.

It is likely that caching and use in different sports will make little, or no, difference at all to the 12 hours of battery life. It only has one job to do.

Like any rechargeable battery, those 12 hours may fall over time and usage. Although Polar do say that you will not notice any degradation in life until after at least 300 full charges.

The biggest danger to the battery life is forgetting to turn it off !

This Polar OH1 review will now turn to the performance characteristics of the product.

In caching mode the ‘battery low’ warning message appears about 2 HOURS prior to total depletion of the battery. The LED flashes change to include RED.

18 months later than has reduced by a couple of hours and, annoyingly, the OH1 loses charge when not in use.


It’s super small (dia 29.85mm x 9.5mm high) and super light (5g sensor + 12g armband). to put that into a real-world context here are some comparisons to an AAA and AA battery, the ones most of us use all over the world, although probably with different names. You know the ones I mean.

This ruler might help even more 😉 as well as a penny/cent.

So IT’S SMALL. Perhaps not ‘tiny’. Here it is compared to the SCOSCHE RHYTHM+ which, by comparison, looks like a bit of a beast.

The pod is even smaller than the Suunto pod and Polar’s relatively new H10 chest strap. H10 reviewed here (link to:

But it looks like the exact same 6-LED sensor used in Polar’s recent higher-end watches, the M430 and M600



Setting up the OH1 will involve pairing it to the Polar FLOW app and then to other apps or devices of your choice.


Out of the box, it DOES immediately pair to other devices and apps. However, it is prudent to take one minute to ‘set up’ the OH1 using the Polar Flow app (v3.6.0 and above). This simply involves pairing to the FLOW smartphone app and setting the wear-position – upper left arm for me.

It’s likely you’ll be asked to update the firmware, which is automatic and takes 10-20 minutes.

Conceptaully, see Polar FLOW app as the ‘maintenance’ app and the app to view your stats. Polar BEAT records the workout.

I reckon there’s a good chance that Polar will add several features to the OH1 over time and so you should return to Polar FLOW periodically to check if there are any updates to firmware.


All apps will pair to the OH1 in subtly different ways. I paired to all these apps to at least prove to myself that they displayed my heart rate: Polar Beat; WAHOO Fitness; and STRAVA.

If you simultaneously try to pair to more than one OPEN app on your smartphone the last app you try won’t work. Close the apps down. Minimising them is NOT closing them.

Here it is paired and working in Polar BEAT.

And similarly, here it is paired and working in the WAHOO Fitness app

Polar does not specifically state which apps the OH1 is compatible with. It’s likely to be a long list and there’s no reason why it will be any different to those supported by Scosche as this image indicates:

Image Source:



The initial pairing of the OH1 to several devices I tried seemed to take several 10s of seconds. If you just leave it, the pairing figures itself out, unless actively paired elsewhere. In that latter case you will NOT be able to pair it to a new device.

I specifically tested the pairing with several of Polar’s devices as well as to a Suunto SPARTAN, a WAHOO bike computer and several apps via an Android smartphone. Everything I tried worked. Indeed any modern device that supports Bluetooth SMART should work and that includes newer high-end Garmins. So, basically, as a broad guide to you, pretty much everything MODERN SHOULD work with the OH1 except older & lower spec’d Garmins (using ANT+).

You might have problems with how some smartphone manufacturers implement Android and there could be other vagaries. Polar haven’t tested all of the thousands of combinations and neither have I. Sorry.

Points on pairing

  1. You can store the pairing of your OH1 simultaneously on lots of devices and/or simultaneously in lots of apps. HOWEVER only one of those pairings can be active. So if you have Polar BEAT either open or open and ‘minimised’ then you will NOT be able to pair to ANYTHING else. Fully close Polar BEAT (or whatever active app is open)
  2. If your device appears to have suddenly stopped working then there’s a good chance your smartphone in the next room is the cause of your problems 😉 ie the smartphone+app is actively paired to your OH1. That’s Bluetooth SMART for you…Polar can’t change that.
  3. If Polar FLOW is synchronising in the background then you will not be able to pair or connect to your OH1.
  4. If you use many smartphone apps on any one smartphone then you have to pair the OH1 with every app. ie you do NOT pair it with the smartphone, you pair it WITHIN the app. Every app. It will only work with one at once.


This Polar OH1 Review will now cover general usage considerations before going on to look at how to start, stop and cache your workout.


Polar does not specifically recommend wearing the OH1 on the wrist. They show ‘models’ wearing the OH1 on the upper arm or the upper part of the lower forearm. Indeed, those wear-locations are the ones that can be selected when setting up the OH1 in the Polar FLOW app. However, there is no reason at all why you couldn’t wear it anywhere else; you will even get a reading if you hold the sensor against your thumb.

You would typically wear it with the OH1 sensor on the OUTSIDE of the upper arm – that’s what I do.

I found the adjustable strap to be relatively comfortable. You will see later that I got good accuracy results and there was no need to have the strap fastened tightly.

It is one continuous elasticated strap and there is no clasp to unbuckle. You just slide it up your arm into position and ensure it is tight enough. This probably takes 5 seconds and there’s no reason why you would not do that in a leisurely triathlon.

The LEDs clearly indicate the mode the OH1 is in. If you don’t wear the OH1 the ‘right way’ around then you won’t be able to see the LED when it’s on your arm. ie point the LED upwards

It can be worn under a wetsuit. My wetsuit is relatively thin and I would suggest you take a degree of care when getting into and out of your wetsuit. I did wear it under a wetsuit, everything WAS good but I would NOT recommend it. Eventually you will rip your expensive wetsuit.


You might also want to consider these general usage points:

Polar OH1 Transmitting underwater – note the bubbles


A short, single button press turns the OH1 on. If you’ve already paired it to another watch or app then you are good to go.

Next, you can press the button twice to enable cached recording on the OH1.

A long button press turns it off.

A subsequent section looks at the various LED colours/flashes, some of which you will need to familiarise yourself with over time to ensure that the OH1 is doing what you think it is.


The Polar FLOW app helpfully tells us that cached data is automatically synchronised after training. It’s not quite so simple.

Cached data can be sent to Polar FLOW in one of two ways.

Firstly, with the OH1 turned back on after you have stopped recording then all you have to do is start the Polar FLOW APP on your smartphone and your workout will be sent to FLOW on both your smartphone and online. The blue light on the OH1 will flash and your smartphone will probably display two arrows going round in a circle on the top status bar, or similar, as shown below. You will probably also get the message “Polar Flow is syncing” in your notifications, or similar. If you close the Polar FLOW app too soon then your workout may not have completed synchronisation. Open FLOW again and all will be good if you let it finish.

Secondly, even if the device is turned off, when charging on your computer it will automatically sync through Polar FLOW SYNC, if you have that software installed.



The speed of synchronisation will depend on many factors such as number of sessions to be sync’d; duration of settings to be sync’d; whether you use the FLOW app or FLOW SYNC (latter is faster); speed of your Bluetooth/wifi/internet connections. To generalise I would say it will take tens of seconds or a minute, or so, rather than minutes or tens of minutes. It’s relatively quick but not instant on a smartphone.

Synchronisation via Polar Flow Sync on your computer takes seconds and is much quicker than Flow Sync with Polar’s watches.

During synchronisation, the time and date will be set on the OH1. There could be quite a few scenarios where the time used for cached data is a few seconds out from the exact, correct time. When comparing to other devices I sometimes had discrepancies of over a minute, which I was not expecting.

When using cached data it is always assigned to the ‘Other Indoor’ sport profile by default. This default sport setting cannot be changed but the sport can be manually changed in FLOW once your specific workout has been sync’d to FLOW.

Change the sport type in Polar FLOW here

When paired to a watch or used in an app, no sport profile is activated on the OH1, it is just the sports profile on the watch which is active. However, if you enable recording/caching then the ‘other indoor’ profile will be used for the recorded/cached workout regardless of what may be happening simultaneously on a paired Polar sports watch…confused yet? 🙂


This is one of those ‘heads-up’ sections. Especially for those of you with experience of how other vendors implement caching.

If you turn on your Polar BEAT app and then you turn on your OH1, everything should be hunky dory as you start to record the session.

However, if you go out of range then this will happen

ie when you are out of range NOTHING is recorded.

Even when you return to range NOTHING is retrieved from the cache. You will only ever have what is shown above…ie a gap in your recording.


A: You forgot to specifically turn the caching on.


Even if you had turned the caching on Polar Beat would still have recorded the same track as shown above.

BUT with caching enabled it would have recorded a separate heart rate track. This separately cached track will find its way back to Polar FLOW when it synchronises. There will then be a (partial) duplicate workout. There is no way to combine these tracks.

Note Well: I imagined Polar have implemented the functionality this way because it is the easiest way to get the technology working and to quickly start selling the product. I would hope & imagine that the way this functionality works will be expanded upon and improved throughout 2018.

To be clear: the retrieval of cached workout data is CURRENTLY only supported within the Polar FLOW APP environment.


There are no kinds of vibrations or audible functionality on the OH1. However, there appears to be only one LED on the device yet it can blink and flash in many and varied colour combinations. These colour combinations are included in the Polar OH1 review but are from In reality, some of the colours are not as obviously different as you would think..but it’s fine:

LED Guide





This LED Flash = No Heart Rate…Obviously



Blue flashing LED = Sync’ing


Any Polar OH1 Review is not complete without a good look at the accuracy of the product.

The Polar OH1 is bravely targeting the indoor gym/fitness crowd as well as the outdoor endurance crowd. Accuracy is hard to achieve in gyms/classes and when cycling and when running hard intervals and when swimming.

Talking about the accuracy of GENERAL optical technology: For wrist-based optical HR accuracy, I think it would be fair to say that we have only seen widely acceptable levels of accuracy for steady-state running. Running intervals are hit and miss. Cycling is hit and miss. Swimming is hit and miss and miss again. For indoor usage, when there is very significant wrist movement impacting on optical HR accuracy, then acceptable levels of wrist-based optical heart rate performance are as rare as the lesser-spotted, Outer-Mongolian Scosche.

I’ve had to overcome significant difficulties coming up with the accuracy comparisons that follow. You might call it the results of a labour of love. Or not. There are some more comparison to add fro teh tests where all 4 devices played nice.

Hopefully what is shown will give you an insight into the accuracy of the OH1 compared to various devices: wrist-based optical HR sports watch; chest straps (used as a control and assumed to be ‘correct’); and an upper-arm worn Scosche RHYTHM+.

I’ve had several tests with ‘perfect’ results for all devices. Some of those are shown. But I’ve also included some of the ‘warts-and-all’ tests just to ground the concept of ‘accuracy’ within some form of the reality you are likely to experience.


I did a 20-minute workout to simulate a weights and gym session. 75% upper body where the arms were moving. But even with the 25% of the time on the lower body, I was holding weights which should affect/restrict blood flow in the arms to some degree.

The blue line is for the WRIST-WORN oHR device, in this case, it was the Suunto Spartan Trainer. The wrist has the greatest number of potential bad movement for optical technology so you could equally substitute any other wrist device here and possibly get the same sort of inaccurate results.

Even the Scosche was struggling a little at times.

In this workout, the OH1 is clearly the closest to the chest strap (Suunto Spartan Sport). Not perfect, but pretty good.

Below is a similar workout on the following day but this time the Garmin 235 is the source of optical HR. Again, the wrist-based device has the most problems. You could then criticise the Scosche or the OH1 as being equally as good, or equally as bad as each other – depending on your perspective. The only thing of note here would be several ‘straight lines’ from the Scosche, presumably where it read nothing and guessed at what was in between the readings it did have.

I would say that the Scosche and the Polar OH1 are just about acceptable in the above scenario.

Personally, I would use a chest strap in a gym. But, to be brutally frank, there isn’t much point in recording heart rates as low as these. I typically combine weights with, say, a Wattbike in the same session. So really I’m wearing the HRM for the bike that comes later.

However, the charts above represent a typical ‘worst case scenario’. YOU may well be looking at indoor classes rather than weights. My guess would be that for the CLASS scenario you will typically get better results than I got for weights but not as good as those for running. So, I’d say the OH1 should be good enough for recording reasonably accurate HR in classes.


I draw the line at wearing a plethora of electronic gadgets whilst swimming for any review let alone this Polar OH1 review. So here we have to assume that the Suunto SMARTBelt is correct. As you can see the wetsuit hold the OH1 in place and everything is good (enough).

Not sure why avgHR is zero. Strange (was created as part of a Suunto multisport session)

This time it’s a pool swim. And I have to say this is probably the best ever optical HR I’ve seen in a pool. It’s not perfect. but it’s the first time I’ve been able to use an arm-worn sensor. There was a wristwatch at the same time but the results were not good and distracted from the message about how good the OH1 is when compared to the Suunto chest strap below. I really tried to dislodge the OH1 but failed, I tried so hard I got cramp. I tried all sorts of paces and rests and, as you can see, it’s pretty cool.



Things look great on this steady state run with all 4 devices performing in a manner that I would consider acceptable for my needs. A good sign is that they all give the exact same average HR but, more importantly, drilling down to the detail shows a great match. The Garmin 235 (optical, wrist) is the worst of the 4. Visually inspecting the lines when the chart is enlarged shows that the Polar OH1 is perhaps even a closer match to the Suunto chest strap than the SCOSCHE

Slightly different run and one of the better I’ve ever had with 4 devices concurrently. This time the Polar M430 (with the same Polar 6-LED sensor) takes the role of the wrist-based HR device, with the Polar OH1 data being cached. Only a very slight dropout of the M430 near the start. This session was under-over aerobic threshold with a fast bit at the end to see how the devices reacted to an immediate stop afterwards. All good.

Finally here are some half-hearted hill reps. Awesome performance against the HRM-TRI.

They REALLY are different if you look VERY closely


Here is another chart that illustrates that wrist-worn oHR is prone to issues, with the SCOSCHE and Polar OH1 performing well. The Scosche got it notably wrong in a couple of places, the Polar OH1 performed slightly better but didn’t quite make it all the way down to the true troughs that the Suunto SMART Belt recorded – very close though.


And here is a 5 device HR extravaganza. It is no coincidence that the two wrist-worn sensors effectively fail miserably – the Garmin 235 and the Polar M430. Over a 2.5 hour ride, there is no hiding the potentially obvious conclusion that wrist based optical HR can be inaccurate when cycling (we already knew that).

At about 23 minutes there is a blue spike. This is potentially the only interesting anomaly of the non-wrist devices. Here the chest strap spikes…so we are in a situation where the Scosche and OH1 are probably right and the chest strap wrong. the chest strap may have moved, for example.

Here’s another saying pretty much the same thing. This time it’s the two devices to show how close the OH1 is to a chest strap.

They REALLY are different if you look VERY closely


A key aspect of the Polar OH1 review is that we, at least, get a feel for its accuracy.

When worn on the upper arm both the Scosche and the Polar OH1 can be classed as ‘ACCURATE’ across all the sports tested.

From previous experience, I would have called the Scosche ‘the most accurate optical HR sensor’. The OH1 provisionally deserves that same accolade.

Polar OH1 – Jointly and provisionally; the most accurate optical HR sensor.


The Scosche RHYTHM+ (link to: Scosche RHYTHM Review) is the only directly comparable alternative that I would even recommend you to consider. Broad alternatives include chest straps and optical wrist watches and optical bands of various flavours.

DETAILED REVIEW: SCOSCHE RHYTHM+ Optical HR Band Review Dual Bluetooth Smart + ANT+

Staying with Polar you could instead upgrade to their best chest strap which is the H10 (link to: Polar H10 Review)

Polar H10 Review (2019 update) Comparisons, Polar’s Greatest HRM

Or you could use Polar’s exact same LED sensor on their M430 sports watch (link to: Polar M430 Review) but you might not find the WRIST to be able to produce as accurate data as the OH1 worn on the upper arm.

Polar M430 Review + Discount | Detailed | GPS & Optical Run Watch

2018 sees the arrival of a directly competing product from Wahoo Fitness called the TICKR FIT. I’ve not yet tested the accuracy of that but it should be good enough to give the OH1 a run for its money. As well as having ANT+ and BLE support it also beats Polar with the battery life and a slightly wider strap. The Polar OH1 would still win on its ability to cache workout data for the Polar environment and both may well morph in 2018 to include extra metrics – but it would then only be likely that such metrics will only work on the manufacturer’s own branded hardware. Tread carefully, you Polar owners.

Edit: Here is the review!

Wahoo Tickr Fit Review | Best Optical Heart Rate Monitor?



This Polar OH1 Review has mostly contained my experiences, here is the stated compatibility of the OH1:


Source: Polar (link to:

Product Manual (link to:


Courtesy @hrdlpn


I like the OH1 and would recommend it and I hope this Polar OH1 review demonstrates that. I’m including these problems for completeness. Most of them are minor.



Best REI/Wiggle/PMC price is linked to. $/Eu/£70 and UNlikely to fall in 2018/9.


At the end of this Polar OH1 Review all I can say is that this is a great product that I do not hesitate to recommend

Its strengths lie in the support for the increasing number of sporting APP users and the comfort of the wear-position. It has many and varied uses across lots of sports.

It’s one of the most accurate optical HR devices I’ve used. If not, THE most accurate one.

Polar addresses the needs of its target markets very well.

It’s not perfect. If Polar had only addressed these 3 areas then it would be a world beater and would address the needs of wider sporting markets:

  1. Does not support ANT+ (older Garmin devices, lower end Garmin devices and some gym equipment);
  2. Does not support GYMLINK 5Khz transmission (for some gym uses and underwater live usage to the V800); and
  3. Strap performance could be improved and the longevity of strap is suspect.

Still. None of that is going to stop me using it A LOT.


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