Fourth Frontier X2 – Adds advanced, Premium fitness, Wellness and Sleep Features
Fourth Frontier X2 – Adds advanced, Premium fitness, Wellness and Sleep FeaturesFourth Frontier X2 Detailed Review
Fourth Frontier X2 is a good and unusual continuous ECG chest strap. It features all the standard components of a high-quality chest strap. Still, it adds several unique features, including recording a detailed and continuous ECG trace as a precursor to conversations you might have with your doctor about heart issues. It also features active alerts to warn you about heart events instantly. These features are specifically targeted at older athletes concerned about developing heart issues and those with known or suspected heart conditions.
Fourth Frontier X2
24x7 ECG, Real-Time Alerts and Sports Tracking.
new VO2max – the most accurate measured outside a lab (claim)
The Fourth Frontier X2 now features an ECG-based VO2max estimation, determined during exercise, which reflects cardiovascular fitness and overall health. Higher VO2max levels are associated with improved athletic performance, reduced risk of heart disease, and increased longevity. It is probably the key metric to improve for any human to experience the best possible health span.
The X2’s ECG-driven technology improves accuracy over legacy straps and even the latest optical heart rate monitors on watches, susceptible to motion and skin tone variations. Unlike typical fitness trackers, the X2 provides continuous, real-time, high-quality ECG data that accurately tracks workout measurements. Combined with Fourth Frontier’s Metabolic Profile Analysis, this accuracy allows users to estimate VO2max outside a lab.
This method also enables Fourth Frontier to determine VT1 and VT2, ventilatory thresholds, which may be more beneficial to regular athletes than lactate thresholds defined by a one-off lab test. To generalise: those two threshold types will be broadly similar and actionable in the same way.
The algorithms used by Fourth Frontier are outlined in the VO2 Max Validation Study.
new Readiness Score
The Fourth Frontier X2’s readiness score is based on multiple inputs, providing a comprehensive view of daily preparedness.
Heart Rate Variability (HRV) is a primary factor that reflects stress and recovery through the autonomic nervous system’s control of heartbeat intervals. Other vital inputs include sleep quality (especially deep and REM sleep) for recovery and physical and mental stress levels, influencing HRV and resting heart rate. Training Load, based on recent workout intensity and duration, also affects readiness by adding muscle fatigue and cardiovascular strain.
Nutrition and hydration play a further role, as balanced intake supports recovery, while illness or injury can lower readiness as the body prioritises healing. Finally, alcohol and stimulants, like excessive caffeine, can disrupt sleep and impair recovery, further reducing the readiness score. Together, these inputs help users gauge and optimise their daily activity levels.
To use the readiness score on the Fourth Frontier X2, check it daily to see how prepared your body is for physical or mental activity. A high score means you’re ready for intense workouts, while a low score suggests taking it easy with activities like yoga, recovery running, or even walking.
To improve your readiness score, focus on quality sleep, manage stress with relaxation techniques, and balance intense workouts with rest days. Maintaining good nutrition and hydration also supports recovery. By monitoring and adjusting activities based on your readiness score, you can make steady fitness gains while reducing the risk of injury.
new Sleep Stage Analysis
Broadly speaking, deep sleep is for physical restoration, while REM sleep is for cognitive restoration.
Fourth Frontier X2’s Sleep Stage analysis offers Premium Subscribers valuable insights into the quality of their sleep and the duration spent in each stage. Understanding these patterns can optimise sleep habits, ultimately enhancing overall well-being and performance. The Frontier X2 utilises advanced sensors to track heart rate, movement, and breathing continuously. Unusually, Fourth Frontier X2 stands out by utilising continuous ECG technology, which theoretically provides superior sleep stage tracking due to its highest level of accuracy in raw metrics, including heart rate and HRV data.
Few, if any, wearables are validated for accurate sleep stage determination against a lab-grade polysomnograph. No reviewer can do this.
Take Out
Some valuable features for premium subscribers.
I like that consumers use the most accurate raw inputs possible for the algorithms. That said, the algorithms have limitations, notably the sleep stage algorithm.
Fourth Frontier X2
24x7 ECG, Real-Time Alerts and Sports Tracking.
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Continous chest strap monitor to get reliable overnight HRV is something I’m interested in. But not at any monthly cost let alone £14 a month!
DFA a1 is a very interesting metric, but fixed thresholds aren’t the best from the most recent studies. You can also use it via Garmin and AlphaHRV for free with any chest strap. AlphaHRV also reports ventilation rate.
fourth Frontier reference dfa a1 in some of its communiations eg the VT study linked to. However I don’t know if they use it in their algorithms…they might.
dfa a1 uses somewhat abitrary fixed values for its ‘threshold’ and yes you can use it if you have a high end ecg strap working in the garmin environment
DDFA is perhaps the new one that you were talking about which is more dynamic than dfa a1?
I was more referencing Bruce Rogers team’s latest paper on how dfa a1 thresholds need to be personalised. If you check his blog he has a paper on it. Or check the intervals.icu forum thread on Alpha HRV.
This strap is £450 a cheap H9 will do for AlphaHRV!
yes to all !
Fourth Frontier is coming at the market from the angle of people who have health concerns and may do sports (even to a high level).
They offer a one-product solution to quite a few issues. Yes you could more cheaply buy an H9/H10 and other apps to go with it if you have the time to curate and setup such apps.