Vagal HRV: Guided Breathing
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About this app
Vagal HRV trains your breathing with real-time biofeedback — and it starts working with no equipment at all. When you want to measure heart rate variability (HRV), it uses a Polar H10 chest strap.
STARTS WITH NO SENSOR AT ALL
Guided breathing runs on the phone alone: pick a protocol (Coherence 6, Box 4-4-4-4, Relax 4-7-8, extended exhale), follow the pulsing circle, done. No strap, no account, no subscription.
When you want to measure your HRV, that is when the Polar H10 comes in.
FREE, NO SUBSCRIPTION
No ads, no mandatory account, no hidden paid tier. Everything below is available the first time you open the app.
VAGUS NERVE, VAGAL TONE AND HRV
The vagus nerve is the main pathway of the parasympathetic branch of the autonomic nervous system, the side that slows the heart down between one beat and the next. The variation in those intervals is exactly what HRV describes — which is why RMSSD is used as a readout of vagal tone in exercise physiology and in research on stress and recovery.
Breathing slowly, with the exhale longer than the inhale, widens that variation while you breathe. The phenomenon has a name: respiratory sinus arrhythmia (RSA). In Vagal HRV you watch it happen live, beat by beat, instead of reading about it.
KEY FEATURES
• Guided breathing — pulsing circle and soft cues across 4 phases, with ready-made protocols. Works without a sensor.
• Reliable HRV — RMSSD, SDNN and max/avg/min HR from the real RR intervals of the Polar H10.
• Readiness — a score compared against your own baseline, with a green/amber/red signal.
• Cardiac coherence (RSA) — watch your heart rate swing in sync with your breath, live.
• Coherence training — daily program with a streak and a weekly goal that grows.
• Resonance frequency — find the breathing rate that amplifies your HRV the most.
• Context tags — log sleep, alcohol, training and stress, and see what moves your numbers.
• Trends and history — 7 and 30-day averages, best time of day, CSV and PDF export.
• 6 languages.
MEASURE ON A PROTOCOL, NOT AT RANDOM
A single number tells you nothing. HRV shifts with time of day, posture, coffee, alcohol and sleep — comparing tonight's reading with yesterday morning's is comparing two different things.
What works is always the same: same time of day, ideally on waking, same posture, a few still minutes before you start. After 7 days you have your own baseline, and that is what the following days make sense against. The app organises that — the 7-day average, the best time of day and the context tags exist for that comparison, not to grade you.
WHY A CHEST STRAP?
Watches and rings estimate heart rate from light (PPG): good at average beats per minute, poor at the exact interval between beats. Since HRV is built from those intervals, the millisecond error that never bothers average HR distorts RMSSD entirely.
The Polar H10 is a chest strap that picks up beat-to-beat intervals directly, the gold standard for HRV — far more reliable RMSSD and SDNN.
WHO IT IS FOR
Runners, cyclists and lifters tracking recovery and training load. People who practise breathwork, meditation or yoga and want to see the effect as a number. Anyone studying their own sleep, alcohol, caffeine and stress. And anyone who simply wants the raw data from their own heart, without an app deciding for them whether the day was good.
PRIVACY
Your data stays on your device. You decide when to export or share it.
IMPORTANT NOTICE
Vagal HRV is intended solely for wellness and sports purposes. It is not a medical device and does not diagnose, treat or prevent any disease.
Polar and Polar H10 are trademarks of Polar Electro Oy. This app is not affiliated with Polar Electro Oy.
STARTS WITH NO SENSOR AT ALL
Guided breathing runs on the phone alone: pick a protocol (Coherence 6, Box 4-4-4-4, Relax 4-7-8, extended exhale), follow the pulsing circle, done. No strap, no account, no subscription.
When you want to measure your HRV, that is when the Polar H10 comes in.
FREE, NO SUBSCRIPTION
No ads, no mandatory account, no hidden paid tier. Everything below is available the first time you open the app.
VAGUS NERVE, VAGAL TONE AND HRV
The vagus nerve is the main pathway of the parasympathetic branch of the autonomic nervous system, the side that slows the heart down between one beat and the next. The variation in those intervals is exactly what HRV describes — which is why RMSSD is used as a readout of vagal tone in exercise physiology and in research on stress and recovery.
Breathing slowly, with the exhale longer than the inhale, widens that variation while you breathe. The phenomenon has a name: respiratory sinus arrhythmia (RSA). In Vagal HRV you watch it happen live, beat by beat, instead of reading about it.
KEY FEATURES
• Guided breathing — pulsing circle and soft cues across 4 phases, with ready-made protocols. Works without a sensor.
• Reliable HRV — RMSSD, SDNN and max/avg/min HR from the real RR intervals of the Polar H10.
• Readiness — a score compared against your own baseline, with a green/amber/red signal.
• Cardiac coherence (RSA) — watch your heart rate swing in sync with your breath, live.
• Coherence training — daily program with a streak and a weekly goal that grows.
• Resonance frequency — find the breathing rate that amplifies your HRV the most.
• Context tags — log sleep, alcohol, training and stress, and see what moves your numbers.
• Trends and history — 7 and 30-day averages, best time of day, CSV and PDF export.
• 6 languages.
MEASURE ON A PROTOCOL, NOT AT RANDOM
A single number tells you nothing. HRV shifts with time of day, posture, coffee, alcohol and sleep — comparing tonight's reading with yesterday morning's is comparing two different things.
What works is always the same: same time of day, ideally on waking, same posture, a few still minutes before you start. After 7 days you have your own baseline, and that is what the following days make sense against. The app organises that — the 7-day average, the best time of day and the context tags exist for that comparison, not to grade you.
WHY A CHEST STRAP?
Watches and rings estimate heart rate from light (PPG): good at average beats per minute, poor at the exact interval between beats. Since HRV is built from those intervals, the millisecond error that never bothers average HR distorts RMSSD entirely.
The Polar H10 is a chest strap that picks up beat-to-beat intervals directly, the gold standard for HRV — far more reliable RMSSD and SDNN.
WHO IT IS FOR
Runners, cyclists and lifters tracking recovery and training load. People who practise breathwork, meditation or yoga and want to see the effect as a number. Anyone studying their own sleep, alcohol, caffeine and stress. And anyone who simply wants the raw data from their own heart, without an app deciding for them whether the day was good.
PRIVACY
Your data stays on your device. You decide when to export or share it.
IMPORTANT NOTICE
Vagal HRV is intended solely for wellness and sports purposes. It is not a medical device and does not diagnose, treat or prevent any disease.
Polar and Polar H10 are trademarks of Polar Electro Oy. This app is not affiliated with Polar Electro Oy.
Guided breathing, no equipment. With a Polar H10 strap, it also measures HRV.
Updated on
Safety starts with understanding how developers collect and share your data. Data privacy and security practices may vary based on your use, region, and age. The developer provided this information and may update it over time.
- No data shared with third partiesLearn more about how developers declare sharing
- No data collectedLearn more about how developers declare collection
What’s new
Now you choose how to start: breathing only, with no equipment at all, or breathing plus HRV measurement with a chest strap.
• Voice-guided breathing, female or male, in the app's language
• Sound options: voice, tone or silent
• Your resonance rhythm, once measured, becomes a breathing protocol
• Cleaner home screen that no longer asks for a sensor you don't use
• Voice-guided breathing, female or male, in the app's language
• Sound options: voice, tone or silent
• Your resonance rhythm, once measured, becomes a breathing protocol
• Cleaner home screen that no longer asks for a sensor you don't use
Everyone
Learn moreApp support
About the developer
CRISTIANA ROLAND KALEFF
contact.akbiosystems@gmail.com
Av. Ricardo Muylaert Salgado, 901
QD J, LT 01-A, VC5
Imboassica
MACAÉ - RJ
27930-860
Brazil