Train heart coherence with a breath pacer that listens back.
Coherence guides slow breathing at your personal resonance pace and shows your heart responding in real time. Five minutes a day builds a calmer, more adaptable nervous system you can measure.
Coming soon: join the launch list below and get it first · What is HRV training?
- ✓ Works with just your camera, no wearable required
- ✓ Polar strap and Muse S supported
- ✓ Free. Outliyr members get every app we build
What is Coherence?
Coherence is a free iOS app that trains heart rate variability (HRV) through paced breathing. It reads your pulse from the rear camera, a Bluetooth chest strap, or a Muse S headband, finds the breathing rate your body responds to best, and scores every session so you can watch your nervous system adapt week by week.
How it works
Three steps to a measurably calmer baseline
Find your resonance pace
A guided sweep tests breathing rates from 4.5 to 6.5 breaths per minute and picks the one that produces your biggest heart rhythm wave. Most people land near 5.5, but yours is yours.
Breathe with the ocean
A natural wave sound swells as you inhale and recedes as you exhale, so you can train eyes closed. Your heart speeds up on the in-breath and slows on the out-breath, and the app shows that wave live.
Keep what works
Every session gets a coherence score. The weekly trend chart shows whether your practice is building, and adaptive pacing nudges your rate when the data says a neighboring pace works better.
Built for real training
Feedback quality decides whether breathwork actually trains anything
Start with zero hardware
Your fingertip on the rear camera lens gives a real pulse wave. When you want beat-to-beat precision, a Polar H10 chest strap plugs straight in, and a Muse S adds a heart-brain sync layer on top.
Adaptive pacing, bounded
Classical HRV biofeedback trains one fixed pace. Coherence can nudge yours by 0.5 breaths per minute inside the 4 to 7 range when a full window of live data shows a better rate, then remembers the winner for next session.
Progress you can audit
Weekly averages of coherence score and time in coherence, session history with scores, and HRV readiness snapshots with your recent baseline. Apple Health gets your mindful minutes, heart rate, and HRV.
Part of the Outliyr platform
Assess, don’t guess
Research averages describe groups, not you. Coherence sessions can sync to your Outliyr dashboard, where n=1 experiments tell you whether HRV training is moving your recovery, sleep, and stress markers, with an evidence-graded keep-it-or-drop-it verdict. Outliyr members get access to every app we build.
What is heart coherence?
Heart coherence is a state where your heart rate rises and falls in a smooth, regular wave synchronized with slow breathing. It reflects healthy communication between your heart and brain through the baroreflex, and it is trainable: breathing near your personal resonance rate, usually five to six breaths per minute, produces the biggest wave. Regular practice is associated with better stress recovery, emotional regulation, and higher heart rate variability.
Do I need a chest strap or wearable to use Coherence?
No. Coherence reads your pulse through the rear camera: you rest a fingertip on the lens and the flash lights up your skin. That is enough to see your heart rhythm wave and score sessions. A Polar H10 or similar chest strap upgrades you to beat-to-beat accuracy, and a Muse S headband adds a heart-brain sync layer. Watches like Apple Watch and Whoop send heart rate only, so they cannot drive coherence feedback.
How accurate is the camera pulse reading?
The camera method is photoplethysmography, the same optical principle wearables use, and it captures the rise and fall of your heart rhythm well when your finger stays still and covers the lens evenly. Treat it as a wellness estimate rather than a clinical measurement. For research-grade beat-to-beat intervals, use a chest strap, which measures the electrical signal of each heartbeat directly.
What breathing pace should I train at?
Your resonance pace, which is the rate that produces your largest heart rhythm wave. For most adults it falls between 4.5 and 6.5 breaths per minute. Coherence finds yours with a guided sweep that tests each rate against your live heart data and keeps the winner. If you turn on adaptive pacing, the app can also nudge your pace by half a breath per minute mid-session when a full window of data shows a neighboring rate working better.
Is Coherence free?
Yes. The app is free, sessions stay on your device, and no account is required. Connecting a free Outliyr profile is optional and adds dashboard sync, so your sessions feed n=1 experiments alongside your labs and wearables. Outliyr members get access to every app we build as part of one membership.
Is Coherence a medical device?
No. Coherence is a training and education tool for breathing practice and general wellness. It does not diagnose, treat, cure, or prevent any disease, and its readings are not a substitute for medical testing. If you have a heart condition or take medication that affects heart rhythm, talk with your clinician before starting intensive breathing practices.
Get the app
Be first when Coherence hits the App Store
Take the free three-minute baseline assessment below and you’re on the list: you’ll get the download link the day the app goes live, plus the five-minute protocol we recommend for your first week.
