Resonance: HRV Biofeedback

Most breathing apps give you someone else's breathing rate. Resonance: HRV Biofeedback finds yours. It uses HRV biofeedback to discover your optimal breathing pace — your personal resonance frequency. Your resonance frequency — the breathing pace that maximizes your heart rate variability (HRV) — is unique to you. It's typically between 4.5 and 6.5 breaths per minute, but the exact rate varies by person. Breathing at your resonance frequency triggers a powerful physiological effect called respiratory sinus arrhythmia (RSA), calming your nervous system and building stress resilience over time. NO SENSOR REQUIRED TO USE THE APP A Bluetooth heart rate sensor is only needed to find your resonance frequency and for live biofeedback during training. Once your personal frequency is found, you can practice at your stored pace with no hardware at all. HOW IT WORKS When you do want live biofeedback, connect any Bluetooth heart rate sensor — a chest strap (Polar H10, Garmin HRM-Pro, Wahoo TICKR), an optical arm band, or a GPS smartwatch with heart-rate broadcast enabled (Garmin, Polar, Wahoo, Samsung, Amazfit, Fitbit). Resonance: HRV Biofeedback reads your live heart-rate stream and runs real-time HRV analysis as you breathe. The three-phase ASSESS → REFINE → HOLD protocol guides you through candidate breathing rates over about 12 minutes, scoring each using the published Shaffer et al. (2020) six-criteria coherence model. Your personal resonance frequency is then locked in and used for training. From there, the app adapts. Each session refines your frequency using an iterative optimization strategy, so your practice improves the more you use it. KEY FEATURES • Real-time breath pacer with animated visual and audio cues • Live heart rate trace showing your HRV response as you breathe • Personalized resonance frequency discovery (ASSESS → REFINE → HOLD) • Session Quality Score tracking real physiological improvement over time • Session history with HRV trends over time • Practice reminders on your schedule • Works with chest straps, arm bands, and GPS smartwatches — any standard BLE heart rate sensor • Sensor-free practice sessions once your resonance frequency is found THE SCIENCE Resonance: HRV Biofeedback is built on 30+ years of peer-reviewed HRV biofeedback research. The analysis engine uses Lomb-Scargle spectral analysis, the HeartMath coherence ratio, and the full Shaffer six-criteria coherence model — the same methods used in clinical biofeedback settings. Your heart rate data never leaves your device. *Resonance: HRV Biofeedback is a wellness tool and is not intended to diagnose, treat, cure, or prevent any medical condition. References: Task Force (1996), Lehrer et al. (2000), Shaffer & Ginsberg (2017), Shaffer et al. (2020). COMPATIBLE DEVICES Any Bluetooth 4.0+ heart rate sensor using the standard Heart Rate Service profile — chest straps, arm bands, and GPS smartwatches. Tested with Garmin HRM-Pro, Polar H10, Wahoo TICKR, and Garmin, Polar, Samsung, and Amazfit smartwatches with heart-rate broadcast enabled. WHO IT'S FOR Athletes tracking recovery. People managing stress and anxiety. Anyone who wants to go beyond a daily HRV number and actually train their autonomic nervous system. No prior HRV knowledge needed, and no hardware required to get started.