Fourth Frontier Frontier X2 Smart Heart Monitor

The Fourth Frontier Frontier X2 Smart Heart Monitor is claimed to be the first heart rate monitor that performs a continuous ECG, or electrocardiogram. It's a specialist bit of kit that delivers on its promise, offering valuable insights into your heart's activity during daily activities and exercise. The app is also easy to use, though the price tag means it's not for everyone (check out guide to the best heart rate monitors for more affordable options).

Measuring the electrical activity of your heart is not a novel concept, but conventional ECGs often require bulky and heavy devices that don't work well for daily activities and exercise.

You can measure lots of metrics while riding, such as heart rate, power, cadence, glycogen levels and core body temperature. The Fourth Frontier X2 adds to that list, providing continuous ECG monitoring.

How does it work?

In the box you get the Frontier X2 device, an adjustable chest strap, a micro-USB cable and a start-up guide. It's packaged well, and is pleasing to unbox.

The Frontier X2 clips onto the elastic chest strap in the same way as a standard heart rate monitor from the likes of Garmin or Wahoo, but has that unique selling point of performing continuous ECG monitoring, showing how your heart is beating.

In addition, it measures heart rate, heart rate variability, which is the regularity between the heart rate pulses, breathing rate, heart strain and body shock, which is body weight over seconds.

The device has the option to measure 20 different activity types, though it's not clear what would change if you picked one activity over another. It's IP67 rated so is waterproof up to 1.5 metres, making it suitable for swimming, though this is purely based on the rubber bung on the micro-USB port being fixed securely. One limitation of this is that the rubber bung comes off fully every time you need to charge it – it's not attached to the device. Something more integrated would be better; I can easily imagine this falling on the floor when I'm charging the device, and since it's such a tiny piece there's a high risk of losing it.

While I have no way of testing the accuracy of the ECG graphs, it recorded in a way that you would expect it to, and hasn't missed a beat.

In use

The Frontier X2 can be used during exercise and daily activities and will be of most benefit to people who are worried about their heart health, but it could also be useful to any sportsperson to help them understand their heart's response during training and racing. And, if you love data, it adds another dimension to your training with other metrics alongside ECG and heart rate, as previously mentioned.

It's designed to work continuously with the Frontier X app, which is available on Android and iOS. You receive feedback through the app on things such as whether you're under or over-training, need more cardio, more power, and so on.

The app is well laid out, intuitive and easy to use. You can see your live ECG through the app, and you can continuously stream this to another person by generating a link.

All workouts are saved to the cloud unlimited for free. However, since it does a lot of analysis of data after an activity has been recorded, it takes a while before you can view the ECG data. I'd say it took around 10 minutes between finishing a ride and the ECG data becoming available.

The device features one button and easy-to-understand LEDs that flash at you – for example, blue when it's looking for devices. Connecting the device to both my Hammerhead Karoo 2 and the app was straightforward. Apart from one pairing mishap at the start, it has worked seamlessly ever since, and you can pair both simultaneously by pressing the button once. Viewing your ECG data needs to be done through the app, but you can see your heart rate through your bike computer.

It's worth noting that you need to press the button on the device to start an activity before it will start recording heart rate or ECG data, which is different to a standard heart rate monitor.

Usefully, if you have some kind of episode during a ride – like a spike in heart rate or you feel lightheaded – you can log it by pressing the button on the Frontier X2 once and it will set a marker at this point, so you can easily find the event when the data uploads to the app or web.

You can set two alerts while you're exercising – a single buzz and a double buzz. You could, for example, set upper limits for both breathing rate and heart rate, or upper and lower limits for just heart rate (or just breathing rate), so it will vibrate when you're outside of those limits. This will be useful if you have a heart condition and you don't want to exceed a certain heart rate, but setting a lower limit to make sure you're not riding too easy could also be useful.

The Frontier X2 features an LED screen, which I was intrigued by, but I think the device could be made lighter and sleeker by getting rid of it, as it's redundant once the chest strap is on and recording. It serves little purpose beyond indicating battery status because you can't read it easily; you need to access the ECG data through the app and your heart rate data on either your bike computer or the app instead.

Despite it being bulkier than a standard heart rate monitor, I did find the Frontier X2 comfortable to wear. It features an elasticated strap that is highly adjustable and fastens in a similar way to that of a Wahoo or Garmin heart rate strap.

Data

As I've said above, you can access your data using both the app and a computer. You can see much more detail when viewing the graphs on a computer, as below, but the app still offers sufficient detail to see whether your rhythm is regular or irregular, and alert you to any issues that may need a closer look on the computer.

The ECG data has good granularity – you can clearly see the spikes in the line rather than it being smoothed out – and the Frontier X2 records data in a way that you would expect it to, which could be valuable to show to healthcare professionals. You also have access to one follow-up session with an expert to gain a better understanding of how the device works.

Battery life

The Frontier X2 has a claimed battery life of up to 24 hours of continuous use, and 12-15 days under typical usage. I wore it on a day-long expedition (10 hours) with no sign of a low battery warning, so I have no trouble believing those claimed run-times.

I'd say battery life is more than adequate for this device, and will likely outlast your bike computer, although it's short compared with a standard heart rate monitor, and you are going to need to remember to charge it up.

It fully charges in 45 minutes, but it's micro-USB charging rather than the more modern and faster USB-C.

Value

The Frontier X2 is a specialist, niche bit of kit that I would recommend if you need the special features, such as the continuous full ECG trace. Although personally I would find the price off-putting, it garnered a lot of interest from members of the local cycling club who have concerns about heart health, particularly middle-aged riders, one of whom has a heart condition.

Compared with a standard heart rate monitor, the Frontier X2 is expensive. For example, Polar's H9 heart rate sensor, which Ed reviewed last year, is £51.50, super comfortable and reliable, with many features of its big brother, the H10, but in a more affordable package.

The H10 costs £76.50 and has some ECG tracking but not real-time streaming of ECG or the ability to perform alerts; the Frontier X2 is unique in its ability to continuously monitor and store ECG data.

Conclusion

Overall, the Frontier X2 Smart Heart Monitor does what it says on the tin, performing continuous ECG, along with recording heart rate, heart rate variability, breathing rate, heart strain and body shock. Although it's comfortable to wear, I think the device could be made sleeker by getting rid of the screen, as you can't read it once the chest strap is on. Personally, I would struggle to justify the price, but it does what it's meant to very well, so if you're concerned about your heart health it's well worth considering.

Verdict

Specialist device that comes at a cost, but particularly useful if you are concerned about your heart health