IntervalGuide vs Resonance

Your workout. Your rules. IntervalGuide is a fully customizable interval timer for HIIT, Tabata, boxing, and circuit training - built to work exactly the way you train. Design your interval workout block by block: set work and rest periods, add rounds, choose audio cues, and train in the right heart rate zone. Shake your iPhone to pause or resume - no need to touch the screen mid-round. Whether you're doing HIIT, boxing rounds, kettlebells, running intervals, or strength-training rest periods, IntervalGuide adapts to your routine, not the other way around. HANDS-FREE CONTROL Shake your iPhone to pause or resume - no need to remove your gloves, stop your set, or fumble with your screen. Perfect for boxing, kettlebells, winter runs, or any workout where touching your phone isn't an option. FULLY CUSTOMIZABLE TIMERS Build workouts your way: - Create unlimited interval blocks with custom durations - Set work, rest, and preparation phases - Add rounds and repeats to any block - Assign colors to visually distinguish each phase - Save and reuse your favorite workouts REAL-TIME HEART RATE Connect your heart rate monitor and train in the right zone: - Polar sensors supported out of the box - Generic Bluetooth Low Energy (BLE) heart rate devices - Live HR display during workouts - Customizable heart rate zones - Apple Health integration AUDIO & HAPTIC CUES Stay focused without watching your screen: - Voice announcements for phase changes - Boxing bell and other sound effects - Vibration alerts to keep you on track - Works with headphones and AirPods APPLE WATCH COMPANION Control your workout from your wrist: - Start, pause, and stop from your Apple Watch - See timer and heart rate at a glance - Full data sync between iPhone and watch WORKOUT HISTORY Track your progress over time: - Automatic session logging - Review past workouts with full details - Heart rate data for every session - Apple Health sync BUILT FOR REAL TRAINING No bloat, no social features, no accounts required. Just a powerful, reliable interval timer that runs in the foreground and never quits on you mid-workout. Works great for: - Boxing & MMA rounds - HIIT & Tabata - Strength training rest periods - Yoga & stretching flows - Running intervals - CrossFit-style WODs - Physical therapy exercises Download IntervalGuide and build the interval timer that fits your training - not someone else's. SUBSCRIPTION IntervalGuide Premium removes all ads, unlocks your full workout history with detailed session stats and HR charts, and lets you export sessions as CSV, Excel, JSON or Text. - IntervalGuide Premium: auto-renewing monthly subscription - Free for the first week for new subscribers, then the price shown in the app - Payment is charged to your Apple Account at confirmation of purchase - Renews automatically unless cancelled at least 24 hours before the end of the current period - Manage or cancel anytime in your Apple Account settings Terms of Use (EULA): https://tremia.app/apps/interval-guide/terms-of-service Privacy Policy: https://tremia.app/apps/interval-guide/privacy-policy

Most breathing apps give you someone else's breathing rate. Resonance: HRV Biofeedback finds yours. Your resonance frequency — the breathing pace that maximizes your heart rate variability (HRV) — is unique to you. It's usually 4.5 to 6.5 breaths per minute, but the exact rate is personal. Breathing there maximizes respiratory sinus arrhythmia (RSA) — the natural rise and fall of your heart rate with each breath. A generic pace like "6 breaths per minute" misses it for most people. Resonance uses live HRV biofeedback to measure your actual resonance frequency, then trains you at that exact pace. START WITH THE WATCH YOU ALREADY OWN Turn on heart-rate broadcast on your Garmin, Polar, Samsung, or Fitbit watch and you're ready — no extra hardware to buy. Any Bluetooth chest strap or arm band works too (Polar H10, Garmin HRM-Pro, Wahoo TICKR, and more). You only need a sensor twice: for the 12-minute assessment that finds your frequency, and whenever you want live coherence biofeedback. Every daily practice session after that runs at your stored pace with no sensor at all. FIND YOUR FREQUENCY IN ABOUT 12 MINUTES A three-phase protocol — ASSESS, REFINE, HOLD — scores candidate breathing rates against your live HRV using the published Shaffer & Meehan (2020) six-criteria coherence model, then locks in your personal resonance frequency and refines it each session. LIVE HRV BIOFEEDBACK, NOT A BLACK BOX • Real-time heart-rate trace and frequency spectrum during every session • All six Shaffer coherence criteria live — peak LF power, single-peak dominance, LF concentration, peak height, SDNN, RMSSD • Watch your heart rate turn into a smooth, sine-like wave as heart coherence builds TRACK REAL IMPROVEMENT • Session Quality Score (0–100) after every session — time in coherence, RSA amplitude, and consistency, scored separately • Full session history with HRV trend charts for coherence, resonance, RMSSD, breathing pace, and heart rate • Shareable session cards with your actual heart-rate trace BUILT FOR DAILY PRACTICE • A calm breath pacer with visual, audio, and haptic cues for eyes-closed sessions • 10 sound packs and a breathing exercises library with multiple session modes • Custom inhale/exhale ratio and practice reminders PRIVATE BY DESIGN Your heart-rate data never leaves your device. No account, no cloud, no sign-up. Everything works offline. FREE TO START The full resonance assessment and unlimited practice are free. Resonance Pro adds the adaptive pacer, full breath history, the complete resonance score, sound packs, and the exercises library — available monthly, annually, or as a one-time lifetime purchase. THE SCIENCE Built on 30+ years of peer-reviewed HRV biofeedback research. The engine uses Lomb-Scargle spectral analysis, the HeartMath coherence ratio, and the full Shaffer six-criteria model, all computed on-device. Resonance: HRV Biofeedback is a wellness and breathing-training tool, not a medical device. It does not diagnose, treat, or prevent any condition; supported heart-rate sensors are consumer fitness devices, not medical hardware. Always seek a doctor's advice in addition to using this app, and before making any medical decisions. References: Task Force (1996) Lehrer et al. (2000) Shaffer & Ginsberg (2017) Shaffer & Meehan (2020) COMPATIBLE DEVICES Any consumer Bluetooth 4.0+ heart-rate sensor using the standard Heart Rate Service — smartwatches, chest straps, and arm bands. WHO IT'S FOR Anyone training heart coherence and resonance frequency breathing as a daily practice. First-timers who want a guided daily practice that works, athletes using breathwork to recover and downregulate, and researchers who want live spectral analysis, RMSSD, SDNN, and raw R-R export. No prior HRV knowledge needed. Resonance frequency breathing. HRV biofeedback. Measured, not guessed. Terms of Use: https://heartresonance.app/terms.html · Privacy Policy: https://heartresonance.app/privacy.html