Optical heart rate monitors have advanced over the last few years, such that they are found on devices across the wearable spectrum. Polar has now taken the tech full circle with the launch of the Polar OH1, stripped of any associated watch, we have a stand-alone optical heart rate monitor to be attached to your arm
Polar OH1 Review – Optical Heart Rate Monitor
Polar launched their foray in optical heart rate sensor devices with the Polar A360, which wasn’t the most accurate of monitors when it first launched – but improved with successive firmware updates. Last year, Polar launched an entirely new six LED optical heart rate sensor on the Polar M600 Android smartwatch. I was exceptionally impressed with the tracking seen on this sensor, both in terms of comparison to other optical HRMs, but also the standards set by the established electrical impulse measuring chest strap HRM technology.
Polar clearly know that they have a reliable sensor with their six LED unit, as we’ve seen the tech trickle down to other devices in Polar’s line up, such as the Polar M430. Now Polar have decided to take the optical HRM full circle and release the same unit as a stand-alone heart rate monitor in the form of the Polar OH1.
That, to me speaks of the confidence that Polar have in their six LED unit. Saying that this isn’t just a supplementary HRM on a sports watch, but is a sensor that can be relied upon in its own right! I think we need to put that to the test!
Polar OH1 Review – Device Design
So what is in the box?
Very little. No excess plastic, just the dead tree manual, the arm strap with attachment clip, a USB charging cradle and the actual Polar OH1 itself. The sensor is surprisingly small, almost comically so, when sat next to a regular HRM,
The small size also gives you an idea of just how much space is taken up by the other gubbins of a sports watch today. Yes, we are lacking a screen, but we’ve still got to have the memory, onboard computer, buttons, charging hardware and Bluetooth radios inside (We’ve not got ANT+ on the Polar OH1, just BLE). Yes, the battery may be on the small size at 45mAh, and is much smaller than a normal sports watch, for example with the Polar M430 having a 240 mAh cell, but we are still looking at a small package here.
In terms of diameter, looking at the sensors on the back of the Polar M600 and the Polar M430, I don’t think that the OH1 could have actually been made any smaller – the actual Polar OH1 alone weights only FIVE GRAMS
On the back of the OH1, we have four flat charging points, which match up with the USB A charging cradle
To the side is the one button, whilst on the opposite is the status light.
You can easily access the button on the side of the Polar OH1 to get things going, either alone or in the strap. I’m actually a real fan of the fact that the unit has a status LED on the outside of the device. I still frequently use the Stryd Pioneer as an HRM unit, simply as it has the status LED to tell me that things are working and that the battery is ok.
The charging puck makes the OH1 resemble a USB thumb drive. Now there is 4 Mb onboard memory, as you can use the OH1 to record your work out without having your phone or other gadgets with you. Wouldn’t it have been terrific, if Polar had added a touch of extra memory so that it could be used as a USB thumb drive as well!
On the arm strap, there is a little cradle to slot the OH1 into, which is quite easy to get the device into and out of. Interestingly enough the button controls are actually printed on the inside of the cradle in case you forget.
The strap, however, holds the unit tightly against your arm, so there is no real chance of the unit falling out even on the hardest of runs
Polar OH1 Review – Specifications
- Weight: 5g OH1 alone – including armband 17g
- The armband is one size fits all… ish – Medium to XXL
- Communication: BlueTooth 4.0 – for data transmission and live HR broadcast
- Size: 9.5mm high, 29.85mm diameter
- Sensors: 6 LED Optical Heart Rate
- Waterproofing: 30 m
- Battery: 45mAh 12 hours of recording
- Memory: 4Mb, enough for 200 hours of recording
The fact that the Polar OH1 does not have ANT+ on board is relatively daft in my opinion. Even if the number of people who are in an entirely ANT+ environment has to be relatively low today, it does still restrict the potential customers. Although from a Zwift perspective, if you are a dyed in the wool ANT+ puritan, you could look to a bridge device such as the WASP CABLE Bridge
Although the Polar OH1 is a pure HRM, and as such could be considered “simple” in function, if not in engineering, it is still worth connecting to the Polar Flow app, just in case you need a firmware update. But this connection is not a requirement, you can still use the Polar OH1 straight out of the box, and attached to any compatible Bluetooth receiver.
Polar OH1 Review – Using the HRM
Polar states that the OH1 has internal memory so that it can be used as a stand-alone device. The manual details easily how to set the OH1 recording internally:
In spite of this apparently ridiculously easy approach – just press the button twice – every time I have attempted to get the Polar OH1 to record when not connected to another device, all I have when I upload to Polar Flow is a blank recording
Maybe it’s me being hamfisted, but it’s certainly been irritating. Perhaps Polar could have changed the LED to flash a different pattern to indicate onboard recording has been activated! As a result, the rest of the testing has been done with Polar OH1 attached to another device
Polar OH1 Review – Optical Heart Rate Accuracy – Cycling
As we know, the vibration on a bike ride can cause issues for optical HRM units to lock on to your pulse when positioned at your wrist. Given the Polar OH1 is advised to be mounted either on your elbow or upper arm, we may see a better trace than a wrist HRM.
So how did things turn out?
All three units actually held up well, for about the first 3 mins the Polar OH1 was a little high, but a shortstop at some roadworks seemed to get everything to line up after. I have found that a brief warm-up is very effective before starting a ride if I’m using optical HRM kit for a personal event, but when testing, I like to just start straight away, as that is how more people will use these devices.
Clearly repositioning the optical sensor to the arm, and the dampening of the vibration at the wrist is a good idea, as the Polar OH1 does track more closely to the 4iiii than the Garmin optical sensor
Polar OH1 Review – Optical Heart Rate Accuracy – Running
I’m not a great fan of things on my arms when going for a run. I’ve tried phone cases attached to my arm in the past, and I just find it a bit of an irritation. Thankfully the OH1 is so light, once I had started running, I basically forgot about it, much the same with a chest strap, and just enjoyed my run
My run over the fields is relative undulating pushing the units to hold a heart rate. Below you can see the graph traces
On the run, as compared to the bike ride, the Polar OH1 holds much more closely to the 4iiii. The Fenix 5 is a little slow from the start, but that isn’t too unusual for that HRM. Even when pushing quite hard, all units track well, until we come towards the end of the run, and the completion of my 5km, where the three feeds start to diverge a little, however based on the rest of the run, I would expect them to come back into line again
Now a simple question may be, “Why have I only produced a chart with only three feeds on it?” Surely, one optical HRM on each wrist, the Polar OH1 and a chest HRM is easy. Well, I’ve done the above graph to look at the OH1, which tracks really nicely with the 4iiii Viiiiva. There was a fourth HRM used… the Suunto Spartan Trainer
Unfortunately, the Spartan didn’t want to play well, and so is waiting for a firmware replacement before I do any more testing with it.
Polar OH1 Review – Conclusion
I like the OH1. It is a VERY light, very reliable heart rate monitor. But it is hamstrung slightly by Polar’s own success. Why opt for an OH1 at £70, when you could actually upgrade totally to a Polar M430, which includes the ability to broadcast the same optical heart rate as well?
If you are dead set on an external heart rate sensor, the OH1 is a good device. For people who don’t like the feeling of a chest strap, the OH1 may be a really good option, especially given that you can use it in the pool! However, units such as the Mio Velo have similar accuracy, and also ANT broadcast, although can’t go into the pool.
Giving ratings on devices is sometimes difficult, I almost think that giving 4/5 is a little harsh, but for some people with ANT+ devices in their sports gear, Polar are cutting them out based on what seems to be old rivalries. Now that Garmin is using Bluetooth sensors as well, this choice simply makes Polar look a little short-sighted. So I’ll give 4/5, due to the acknowledgement that Polar OH1 would have had 5/5 if it supported dual channel comms. However the device as a stand-alone unit is still great, so I think a “recommend” award is still reasonable as well