Frontier X2 Review: Brilliant Continuous ECG, But Is It Worth the Price?

The Fourth Frontier Frontier X2 isn't really competing with an ordinary heart-rate strap. While products such as the Polar H10, Garmin HRM 600 and Wahoo TRACKR concentrate on delivering highly accurate heart-rate information, the Frontier X2 goes much further by recording a continuous single-lead ECG during exercise. It also tracks HRV, breathing rate, training load and cardiac strain, with configurable vibration alerts to warn when selected thresholds are crossed.

That additional information is the X2's strongest reason for existing. Recent professional testing found its heart-rate readings responsive during changing exercise intensity, while reviewers have particularly praised the ability to review ECG information alongside workout data. The 25-gram sensor is light, can record without a phone and provides up to 24 hours of continuous recording.

There are compromises, however. Bluetooth is supported but ANT+ isn't, charging still uses Micro-USB, and continuous battery life is dramatically shorter than conventional heart-rate straps. Some advanced features—including VO₂ Max and readiness-related metrics—also require Frontier Premium despite the X2's already substantial purchase price. User feedback is more mixed than the manufacturer's strong storefront ratings suggest, with reports of connectivity problems, noisy recordings, charging issues and software frustration appearing alongside considerable praise for the ECG information and customer support.

The X2 should also not be mistaken for a medical ECG monitor. Fourth Frontier explicitly identifies it as a health-and-fitness product rather than a device intended to diagnose or treat medical conditions; the company's FDA-cleared prescription product is the separate Frontier X Plus.

The biggest challenge in 2026 may actually come from Fourth Frontier itself. The newer Frontier Zone retains most of the exercise-focused ECG functionality while adding USB-C, substantially improving battery life and reducing the upfront cost, although more functionality is tied to a Premium subscription.

For someone who specifically wants continuous ECG recordings during demanding exercise, the Frontier X2 remains a fascinating and capable device. For everyone simply seeking accurate heart-rate training, a Polar H10, Garmin HRM 600 or Wahoo TRACKR offers dramatically better value. The X2 is therefore a strong specialist tool rather than a universally great heart-rate monitor.