Tuesday, October 10, 2017

Polar OH1 Optical Heart Rate Sensor Review: a comfortable, accurate, and much-welcome alternative to the standard chest strap

Editor's Note: We are thrilled to have Larisa Dannis test and review the Polar OH1 optical heart rate sensor for her first article as a contributing writer at RoadTrailRun.  Larisa is a huge proponent of heart rate based pacing over all kinds of road and trail terrain. Reliable sensing is key for her.  She tested the OH1 while preparing for the Javelina 100 later this month on the trails of New Hampshire's rugged White Mountains, at the Vermont 50, and on the roads.  
The results of her heart rate based training and racing approach shows as among many great results she was 2nd at the Western States 100 in 2014, was US 50 Mile Road Champion (5:59:11), ran 2:44.14 at the 2014 Boston Marathon, and qualified for the 2016 Olympic Marathon Trials. Her personal web site is here.

Article by Larisa Elaine Dannis

Polar OH1 Optical Heart Rate Sensor
$79.95. Available now.

Up until this opportunity to test an optical heart rate sensor, I’ll admit I was doubtful of the technology. Early reviews – especially those covering wrist-based devices – spoke of questionable accuracy, data transmission issues, and a need to cinch the sensors down uncomfortably tightly.

As a gal who’s relied heavily on heart rate data in training and when racing (something I talk about in detail here), I went into this testing period thinking nothing could replace my ever-reliable heart rate chest sensor.

37 hours and 220.6 miles later, the Polar OH1 has thoroughly changed my mind. In fact, at this stage I can’t imagine going back to using a chest strap again .


Note that I tested a beta unit.

The Polar OH1 unit consists of an optical heart rate sensor, a wrist strap, and a USB charger.

Sensor and armband
The sensor and armband are incredibly light, weighing in at 17g (5g for the sensor, 12g for the strap). For reference, here’s a comparison of the OH1 sensor vs. the Polar H7 heart rate transmitter. 

In terms of width, it's certainly tiny; no wider than a small stack of 3-4 quarters.

The sensor battery is rechargeable – and charges remarkably quickly at that – via a separate USB charger. Battery life is advertised at 12 hours, though I’ve yet to take it on an adventure of that length! However, the battery has yet to fail me on multiple 3-4 hour mountain runs.

The armband is discreet and seems to be made of the same material as a Polar heart rate chest strap.  Polar uses six LED lights to illuminate blood flow for its center sensor. Most other optical heart rate monitors use 2-3 LED lights. The Polar M430 GPS watch with wrist heart rate shares the same sensor configuration. (RTR review).

Polar recommends placing the strap on one’s upper arm or forearm. I went with the former, as wearing the strap on my forearm felt a bit strange.

Note: it took me a few runs to dial in on the ideal placement of the armband and sensor. I’ve found that positioning the sensor on my triceps (outer arm, shown below) resulted in the most accurate readings, which is in line with Polar’s recommended placement.

Positioning the sensor on my bicep (inner arm) resulted in some brief data transmission issues between the sensor and my watch.

The OH1 works with all Polar Bluetooth-compatible watches and computers and paired immediately with my Polar V800 watch. It also works with Bluetooth-compatible iOS and Android devices so if you use a run app such as Strava as your tracker, instead of a watch, you can pair the OH1 to the phone and see and capture heart rate data in the app. 

Note that the sensor’s built-in memory can store up to 200 hours of data, making it possible to use the OH1 as a standalone unit for swimming, storing data for viewing after, and the gym, neither I have  tested yet. Wrist heart rate sensors are known to struggle when hands are clenched, reducing blood flow, so the OH1 should be a good option for these uses.


I certainly put my OH1 through its paces – from flatter, faster efforts all the way up to multi-hour mountain runs. Here is where it shined:

Once I dialed in on the placement of the sensor, I found the OH1 to be wonderfully accurate on runs up to 4 hours. As mentioned previously, I monitor my heart rate closely in training, especially during workouts. The OH1 proved to be impressively reliable in this regard (see heart rate track below or on Strava).

Windy conditions, minor temperature fluctuations, rain, and covering the unit with an armband did not impact its ability to transmit data to my watch. I’ll be interested to see if/how colder conditions impact the sensor as we transition into winter here in New Hampshire.

Once adjusted, the armband is comfortable and stays put at all paces. Not once did I have to adjust it on the fly, and compared with a chest strap it’s barely noticeable. Additionally, I was thrilled to note that I didn’t have to cinch it down in order to get accurate readings.

The OH1 is discreet and slim. Dare I say it actually looks good on one’s arm? In the future, I’d love to see Polar come out with additional armband colors, as they do for heart rate chest straps.


We all know technology can be fickle. The only time the OH1 failed me was during a 50 mile race in Vermont. Approximately 37 miles into the run, the unit suddenly stopped transmitting data to my watch (see red arrow below). The screen displayed two dashes (indicating that it wasn’t picking up data), and I was unable to get the sensor to connect to my watch again even after trying to re-position it and switching it on/off a couple times.

The issue did not appear to be battery-related, as the sensor continued to blink green which indicates it’s on. My hunch is that the problem came about due to the unseasonably brutal conditions. Temperatures in Vermont climbed to 90 degrees (at 90% humidity) during the heat of the day, which happens to be when the OH1 stopped working. It’s also possible that the problem is specific to my unit, which happens to be a beta one.


Polar has hit a home run with their first standalone optical heart rate sensor. I highly recommend the OH1 for short-to-mid-duration runs in all but the most extreme of conditions. It’s a reliable, comfortable and much-welcome alternative to the standard heart rate chest strap, and at this stage has replaced my own chest strap entirely.

I’ll be giving it another ultra-distance shot at the Javelina Jundred at the end of October, and look forward to seeing how it performs in the desert.

For Larisa's run bio see our Reviewers Bio Page here

The OH1 was provided at no cost.The opinions herein are entirely the author's.

Comments and Questions Welcome Below!
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Great review