Fourth Frontier launches Frontier X2, a $599 heart rate monitor with continuous ECG

A premium device with continuous ECG and heart rate tracking

The Frontier X2 is a chest-worn heart rate monitor developed by Fourth Frontier, designed to offer continuous ECG functionality and highly accurate heart rate tracking. According to TechRadar, the device uses electrodes to deliver readings that match top-of-the-range wrist-based wearables like the Polar H10, a long-standing favorite among athletes and fitness enthusiasts.

Unlike many competitors, the Frontier X2 includes a screen and a tactile button, features that help users confirm the device is powered on and properly connected. It also supports USB recharging, addressing a common pain point with older models like the Polar H10, which relied on micro-USB chargers.

The device streams ECG data in real time to the Frontier app, allowing users or medical professionals to monitor heart activity during workouts or daily activities. It also calculates metrics such as Strain score, Stress score, Heart Rate Variability (HRV), and Breathing Rate using heart rate data.

Limitations and trade-offs

Despite its advanced features, the Frontier X2 has notable limitations. It lacks ANT+ connectivity, a standard in many fitness devices, which may disappoint users who rely on it for compatibility with other equipment. Additionally, while the device provides calorie burn estimates based on heart rate, TechRadar notes these estimates are unreliable, as they measure effort rather than actual energy expenditure.

The Frontier X2’s price—$599 in the US, £449 in the UK, and AU$775 in Australia—positions it as a premium offering, significantly higher than competitors like the Polar H10. TechRadar awarded the device a value score of 3.5 out of 5, reflecting concerns about its cost relative to its features.

Some of the Frontier X2’s functionality is locked behind a subscription paywall. The premium tier, priced at $119.99 or £109.99 per year, unlocks features like Readiness score, VO2 Max, and sleep stage analysis, which may deter budget-conscious users.

What this means

Lazyfounder analysis — our interpretation, not reported fact.

The Frontier X2 enters a crowded market dominated by established players like Polar, Apple, and Garmin, but it differentiates itself with continuous ECG functionality and a user-friendly design. For founders and operators in the wearables space, the device highlights two key trends: the growing demand for medical-grade health monitoring and the challenges of justifying high price points in a competitive segment.

The subscription model for premium features is a double-edged sword. While it creates a recurring revenue stream, it risks alienating users who expect core functionality to be included upfront. The lack of ANT+ support is another gap that may limit adoption among serious athletes, who often rely on this protocol for compatibility with gym equipment and cycling computers.

For health tech startups, the Frontier X2’s real-time ECG streaming capability could set a new benchmark for consumer-grade wearables. If Fourth Frontier can demonstrate clinical utility—such as detecting arrhythmias or other cardiac anomalies—the device could appeal to a broader audience, including older users or those with pre-existing conditions. However, achieving this will require partnerships with healthcare providers and regulatory clearances, which are not trivial hurdles.

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