ZONE 2 COACHStop policing your heart rate. Let it talk back.
Zone 2 Coach turns any Bluetooth chest strap into a coach on your phone. A tone sounds the moment you leave your zone, even with the screen off and the phone on silent.
Three things it does
It talks
A distinct tone above your ceiling, a lower one below your floor, a chime when you are back. A separate hard ceiling always sounds. It plays on the alarm stream, so it works with the phone on silent.
It keeps running
A foreground service holds the strap connection with the screen off or the app in the background. There is no time limit on recording.
It remembers
Time in zone, HR drift, training load, recovery at 30, 60 and 120 seconds, session HRV and a history you can scroll back through.
8 mornings. 1 baseline that's yours.
Sit still for three minutes each morning with your chest strap. The first minute is thrown away so your heart rate can settle; RMSSD comes from the rest.
For your first seven readings the score is on an absolute scale, which compares you to the crowd and says little. From the eighth, it is compared to your own average and spread: 50 is your normal day.
It describes your own trend. It is not a health assessment.
Free, and Pro
Free, with no time limit
- Zone alerts and the hard ceiling
- Recording with the screen off
- Recovery at 30, 60 and 120 s
- HR drift and training load (TRIMP)
- Session HRV: RMSSD, SDNN, pNN50, Poincaré
- Session history
- Demo mode, no strap needed
- Your first 8 Readiness readings
Pro, one-time, no subscription
- Readiness: a daily 3-minute HRV score against your own baseline, the 7-day trend and the score history
- Raw ECG recorder (Polar H10), saved to CSV
- CSV export of sessions and readings
Price shown in Google Play for your country (3.99 EUR in Italy).
Built on established measures
Nothing here is invented. The numbers are the ones sports science already uses, worked out on your phone:
- RMSSD
- the standard time-domain measure of short-term heart rate variability (Task Force of the ESC and NASPE, 1996).
- HR drift
- how much your heart rate climbs at the same effort between the first and last five minutes of the block. Under 5% the effort is aerobic.
- TRIMP
- training load as duration times intensity, weighted on your heart rate reserve (Banister).
- Recovery
- how many beats your heart rate falls 30, 60 and 120 seconds after you stop.
Reference: Task Force of the European Society of Cardiology and the North American Society of Pacing and Electrophysiology (1996). Heart rate variability: standards of measurement, physiological interpretation and clinical use. Circulation 93(5):1043-1065.
Made by one person
Zone 2 Coach has no account, no ads and no analytics, so a message is the only way I hear what works and what does not. Tell me what is missing or broken: I read and answer everything.
Questions
Which straps work?
Any Bluetooth LE strap that uses the standard heart-rate profile: Polar, Garmin, Wahoo, Coospo, Magene and most others. A wrist optical sensor will not do: for HRV you need beat-to-beat intervals from a chest strap. The raw ECG recorder needs a Polar H10.
Does it work with the screen off?
Yes. A foreground service keeps the strap connected with the screen off or the app in the background, and the alerts play on the alarm stream, so they are heard even with the phone on silent.
Can I try it without a strap?
Yes. Demo mode simulates a heart rate, so you can hear the zone alerts and see every screen before you wear anything.
What happens to my data?
It stays on your phone. There is no account, no analytics, no ads and no server. The only part that talks to Google is Google Play's own billing, and only for the optional Pro purchase.
Is it a medical device?
No. It is training software. It does not diagnose anything and it is not a substitute for medical advice. The ECG feature is a recorder, not an analyser.
iPhone? Another language?
Android only for now, and the interface is in English. If enough people ask, that can change.