HRV-Tracker

Native iOS and watchOS application with advanced Apple Watch complications

Overview

HRV Tracker is a dual-platform application for iPhone and Apple Watch that transforms complex heart rate variability data into actionable health insights. The app reads HRV measurements from Apple Health and presents them through clean, scientific visualizations, an all-day stress curve, and a personalized recovery score. It tracks both SDNN (Apple's standard HRV metric) and RMSSD (computed from raw beat-to-beat intervals) for a comprehensive view of autonomic nervous system activity.

Platform Features

iOS Application

Four dedicated views: Home, SDNN, RMSSD, and Stress
Comprehensive HRV analysis with dual metrics (SDNN and RMSSD)
All-day Stress curve combining heart rate and HRV, with sleep and workout context overlaid
Personalized Recovery score based on your 7-day baseline
Age-adjusted categorization using research-backed thresholds
Daily, weekly, monthly, and yearly trend analysis with interactive charts
Latest reading and time stamp shown alongside the daily average
watchOS Application with Advanced Complications

Full-featured native Apple Watch app with circular Recovery and Stress gauges
Inline SDNN and RMSSD values at a glance
Statistical Z-score analysis based on your personal baseline (7 days)
Dedicated SDNN, RMSSD, and Stress chart complications with live data
RMSSD calculated in real-time from raw RR intervals (heartbeat series)
Background data processing with optimized battery usage
Supports Graphic Corner, Circular, Bezel, Rectangular, and Extra Large complications
Data Requirements

Important: This app provides meaningful insights only when AFib History is enabled on your Apple Watch (Watch app, Heart, AFib History). This feature significantly increases the frequency of beat-to-beat data collection, providing the rich dataset necessary for accurate stress curves, statistical analysis, and personalized baselines. Without it, measurements are too infrequent for reliable trend analysis, stress monitoring, or recovery scoring.

Key Features

All-Day Stress Monitoring

Continuous stress score (0-100) computed at every heart-rate sample for a dense intraday curve
Two physiological signals weighted 50/50: your RMSSD ranked against your personal history, and your heart-rate reserve
Smoothed trend curve showing how stress accumulates and dissipates through the day
Sleep periods shaded and workouts excluded automatically, so the curve reflects genuine autonomic stress
Periods when the watch isn't worn are clearly greyed out
Dual HRV Metrics

SDNN: standard deviation of NN intervals as reported by Apple Health
RMSSD: root mean square of successive differences, from raw heartbeat series data
Side-by-side comparison on iPhone and Apple Watch
Smart Recovery Scoring

A single, unified Recovery score shared across iPhone and Apple Watch
Based on your RMSSD trend versus a personal 7-day rolling baseline
Filtered baseline calculations that exclude statistical outliers
Adaptive algorithm that improves as it learns your patterns
Apple Watch Integration

Recovery, Stress, SDNN, and RMSSD complications on your watch face
Color-coded zones with trend indicators
Synchronized updates via background processing
Clean Data Visualization

Daily, weekly, monthly, and yearly trends with interactive charts
Filtered baselines and personal historical ranges
Color-coded zones inspired by heart rate training systems
All HRV data remains on-device and integrates seamlessly with Apple's Health ecosystem. No data is transmitted to external servers, ensuring complete privacy of your health information.

Target Users: Health-conscious individuals, athletes, and wellness enthusiasts seeking evidence-based recovery and stress insights through HRV monitoring. Requires Apple Watch with AFib History enabled for optimal functionality.