The affordable Polar H9 chest strap tracks heart rate precisely even during HIIT workouts

For many of us, tracking heart rate during exercising means wearing a running watch. And that is fine, the best running watches have capable optical sensors which can monitor heart rate reasonably accurately, as long as you look at the average heart rate and not the lowest or highest heart-rates during the session. Wearables like the Fitbit Versa 2 and the Apple Watch 5 are also relatively precise as long as you don't want to track vigorous exercise.

But if you are interested in your actual heart rate during a full body HIIT workout, for example, you might need a different device. And lucky for you, Polar's new heart rate monitor, the Polar H9 heart rate sensor, is not only precise, but also way cheaper than your average fitness smartwatch.

• Buy the Polar H9 heart rate sensor directly from Polar

The Polar H9 uses Bluetooth and ANT+ technology to connect to your wearable device – my Garmin Fenix 6 Pro picked up the signal from the Polar H9 before the watch picked up the GPS – but even if you haven't got a fitness tracker or can't justify spending loads getting the best triathlon watch, you can track workouts with nothing but the Polar H9 and your phone, using the free Polar Beat app.

You can also use the Polar H9 if you plan on doing indoor training using turbo trainers, like the Wahoo Kickr Snap Bike Trainer: using the also free-of-charge Wahoo app, the heart rate tracked by the Polar H9 compliments the metrics already gathered from the smart trainer.

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How does the Polar H9 heart rate sensor work?

Unlike optical heart rate sensors found utilised on wrist heart rate monitors, the Polar H9 measures your pulse by sending electrical signals through your body, much like how modern digital scales measure body fat percentage.

The information from the Polar H9 then sent to your connected device (smartphone, running watch etc.) using Bluetooth or ANT+. There is no need to turn the Polar H9 on before you start using it, just make sure the back of the strap underneath the sensor is somewhat moist before you put on the chest strap.

The thin layer of water will serve as a transfer medium so the Polar H9 can read heart rate more accurately straight after being put on. There is no need to wet the strap during workout, you will start sweating (presumably) soon enough as your workout gets harder.

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Why should you buy the Polar H9 heart rate sensor chest strap?

For one, the Polar H9 heart rate sensor is affordable; it is around £55/$60, slightly more expensive than a fitness tracker but a hundred times more useful. It is definitely cheaper than buying a new running watch, even just a fitness smartwatch, and will provide you with the most important metric you need: accurate heart rate readings.

Not to mention, since the Polar H9 hasn't got a screen or any optical sensors, the battery life is extra long: it will last for over a year, even if you use it every day for an hour, which you probably won't. Polar states on its website that the battery life of the Polar H9 is up to 400 hours.

• Buy the Polar H9 heart rate sensor directly from Polar

Since the Polar H9 tracks heart rate reliably, this means you'll get more accurate calorie burn estimates too. The strap also sits close to the heart and is fastened securely, so it's ideal for intense HIIT workouts, among other types of exercises.

The Polar H9 can be paired with any compatible app or device that uses Bluetooth and/or ANT+ technology. Of course, you can just use the free Polar Beat app to track a million different exercises, your heart rate during these exercises anyway. To track cadence, you might want to get a Polar Cadence Sensor for your bike. If you want to measure running power (on the wrist), you might want to invest in a Polar Vantage V.

But if you want to get accurate heart rate readings and don't want to spend loads, the Polar H9 heart rate sensor is great choice.

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