SELFLOOPS HRV – Recovery, Readiness & Performance
SELFLOOPS HRV is a professional-grade heart rate variability app designed for athletes, coaches, and researchers. Track recovery, stress, fatigue, and training readiness using precise beat-to-beat (R-R interval) data from Bluetooth heart rate monitors.
Built on sports science principles, SELFLOOPS HRV delivers accurate, actionable HRV insights to help you train smarter and recover better.
Why Track HRV?
Heart rate variability (HRV) measures the time variation between consecutive heartbeats. It is one of the most reliable biomarkers for understanding how your body responds to training, stress, and recovery.
Tracking HRV daily helps you:
- Assess recovery status after training
- Determine training readiness before your next session
- Monitor stress and fatigue levels
- Evaluate autonomic nervous system balance
- Optimize long-term athletic performance
By measuring HRV each morning, you can identify when to train hard, when to recover, and how to reduce the risk of overtraining.
Advanced HRV Metrics
SELFLOOPS HRV provides the key time-domain metrics used in elite sports and peer-reviewed research:
- RMSSD – Root Mean Square of Successive Differences
- ln(RMSSD) – Natural log of RMSSD, our HRV Score
- SDNN – Standard Deviation of NN Intervals
- pNN50 – Percentage of successive intervals differing by more than 50 ms
- AVNN – Average of all NN Intervals
These metrics give you a complete picture of your autonomic nervous system activity and recovery state.
Accurate HRV Measurement
Accurate HRV measurement from beat-to-beat R-R interval data. Requires a Bluetooth Low Energy heart rate monitor. For best accuracy, use a chest strap that supports R-R interval data, such as Polar H10, Wahoo TICKR, or Garmin HRM-Pro.The application can also import R–R interval data from Apple Watch, as well as from any app that writes this data to HealthKit via the HealthKit API. Apple Watch automatically records R–R intervals throughout the day, but you can also trigger a dedicated HRV measurement using the Breathe app (now part of the Mindfulness app), which forces the watch to record and store R–R interval data in HealthKit. Once recorded, this session can be imported into the SELFLOOPS HRV app.
Daily Recovery & Readiness Tracking
Track your HRV daily to monitor recovery and readiness trends over weeks and months. The Readiness Score analyzes how your HRV evolves over time and translates it into a clear, actionable insight to guide your training decisions.Store & Visualize Your HRV Data
The app maintains a complete archive of your HRV measurements and displays R-R interval and heart rate charts so you can track your progress over time.Export & Sync
Upload your data to SelfLoops or export via email, Dropbox, or Google Drive.Key Features
- Accurate HRV measurement from beat-to-beat R-R interval data
- Daily recovery and readiness tracking with Readiness Score
- Trend analysis to monitor progress over weeks and months
- Fast, simple, and intuitive interface
- Compatible with leading Bluetooth heart rate monitors
- Designed for endurance, strength training, cycling, running, and general fitness
Accuracy You Can Trust
SELFLOOPS HRV is built around precision. The app uses raw beat-to-beat R-R interval data from Bluetooth heart rate monitors to ensure measurement quality.
With improved analysis algorithms and enhanced error correction, the app delivers professional-level accuracy — the standard trusted in elite sport and scientific research.
Trends & Readiness Score
The Trends Analysis with Readiness Score is a major addition to SELFLOOPS HRV. Rather than relying on a single daily HRV value, the app analyzes how your heart rate variability evolves over time and translates that into a clear, actionable readiness insight.
How it works:
- Measure your HRV daily, ideally first thing in the morning
- Watch your HRV trend develop over days and weeks
- Use the Readiness Score to guide your training decisions
When readiness is high, your body is prepared for intense training. When it drops, recovery should be the priority. This approach helps you train based on your actual physiological state, not just a fixed schedule.
Built for Real Training
SELFLOOPS HRV gives you the same metrics used in sports science research — like RMSSD and ln(RMSSD) — presented in a way that is easy to understand and act on.
The goal is simple: help you answer one question every day — should I push, or should I recover?
Whether you are an endurance athlete, a strength athlete, or someone serious about fitness, HRV tracking helps you train with more awareness and less guesswork.
Moving Forward
This redesign marks an important step forward for SELFLOOPS HRV. The app is faster, clearer, and more capable — while staying true to its core mission: delivering reliable insights you can use every day.
And there is more to come.
Device Compatibility
Requires a Bluetooth Low Energy (BLE) heart rate monitor. For best accuracy, use a chest strap that supports R-R interval data transmission. Not all heart rate monitors provide beat-to-beat data — check your device specifications before purchasing.
The application can import R–R interval data from Apple Watch, as well as from any app that writes this data to HealthKit via the HealthKit API.
FAQ
Make sure you are using a Bluetooth Smart (Bluetooth 4.0, Bluetooth Low
Energy) certified heart
rate monitor. 
Ensure the sensor is not already paired with another app or device. Also, do not pair the heart rate monitor directly through iOS Bluetooth Settings — let SELFLOOPS HRV handle the connection. The Bluetooth standard does not allow a heart rate monitor to be connected to multiple apps or devices at the same time.
Disclaimer
SELFLOOPS HRV is not a medical device and does not provide medical advice. Always consult a qualified healthcare professional for health-related decisions. For an introduction to HRV see: Heart Rate Variability on Wikipedia.