Fitbit killer Frontier X gives the most advanced heart and LUNG tracking ever

Paula Radcliffe-backed fitness and health strap can help advanced athletes AND those recovering from a heart attack

Frontier X
(Image credit: Fourth Frontier)

Sadly, wrist-worn fitness wearables will only ever get so accurate, but a new chest-worn device called Frontier X is here to change this. Manufactured by Fourth Frontier, the Frontier X continuously measures heart rate, breathing rate and cardiac strain, giving you real-time vibration alerts when you cross thresholds that could "damage your heart", as the company puts it.

Some of the best fitness trackers and best running watches, such as the Fitbit Sense and Withings ScanWatch, can already measure ECG and heart rate on the wrist, albeit not too accurately. On the other hand, the best heart rate monitors can measure heart rate more precisely but lack the user friendliness of wrist wearables.

Realistically, and despite our headline, this is not in the same space as Fitbit or even Apple Watch. It could, however, be very useful for both ambitious athletes and fitness fans, AND people at risk of, or recovering from, heart conditions. That’s thanks to its ability to offer long term ECG tracking of your heart and lung functions. 

Fourth Frontier describes the device as ‘a chest-worn device used for athletic training, cardiac rehabilitation and remote monitoring – made to keep you healthy and away from the hospital.’ It‘s worth noting, however, that it is not a certified medical device, at this point. 

Frontier X

(Image credit: Fourth Frontier)

The Frontier X promises to be more accurate and provide more comprehensive readings than existing wearables. It does so by correlating changes in your ECG with breathing rate, cardiac strain, heart rate, and other activity metrics. Fourth Frontier claims that by using the Frontier X, you can "avoid over-straining your heart" by monitoring cardiac strain and get real-time vibration alerts.

The Frontier X can also help you improve running pace using breathing rate (somehow), monitor ECG remotely, measure workload 'objectively', regardless of sport or environment and even prevent injury by measuring the shock your body suffers during each foot-strike to reduce injury.

Fourth Frontier also suggest that the device can both look out for potential heart conditions, and be used to monitor those who have been diagnosed with them, so it could save you a lot more than a few seconds on your 5k personal best.

Frontier X

(Image credit: Fourth Frontier)

The Frontier X is IP67 rated and waterproof up to 1.5 metres. Battery life is 'up to' 24 hours of continuous use or two weeks of 'typical use'. There is also an option to see real-time data on Apple watches and Apple/Android phones plus to live-stream and record ECG for up to 24 hours. Detailed ECG summary is available on the web app.

The Frontier X has a screen which seems a bit pointless as you can't really see it when the device is at work but it can at least send vibration alerts when you cross your effort and strain thresholds. Workout highlights can be viewed on the Frontier X's screen and workout summary on your phone afterwards.

As we mentioned before, this is not a medical device, but it could be a useful addition to your cardio training fitness arsenal. 

The Frontier X is available to buy directly from Fourth Frontier for $399 / £303.

Matt Kollat
Section Editor | Active

Matt Kollat is a journalist and content creator who works for and its magazine counterpart as an Active Editor. His areas of expertise include wearables, drones, fitness equipment, nutrition and outdoor gear. He joined T3 in 2019. His byline appears in several publications, including Techradar and Fit&Well, and more. Matt also collaborated with other content creators (e.g. Garage Gym Reviews) and judged many awards, such as the European Specialist Sports Nutrition Alliance's ESSNawards. When he isn't working out, running or cycling, you'll find him roaming the countryside and trying out new podcasting and content creation equipment.