Heart Rate Variability Logger 4+‎

Heart Rate Variability Logger lets you record, plot and export time, frequency and non-linear HRV Features (includes experience sampling, RR-interval correction, DFA alpha 1 for aerobic threshold estimation in real-time, comparison between recordings, activity monitoring & step counting, location tracking).

Heart Rate Variability Logger requires a Bluetooth Low Energy (also called Bluetooth Smart or BLE or 4.0) heart rate sensor (we recommend Polar H7 or H10)

Main features:
- Extracts, plots, stores and exports heart rate, rr-intervals, time and frequency domain heart rate variability features (AVNN, SDNN, rMSSD, pNN50, LF, HF, LF/HF, alpha 1 from DFA)
- Configurable experience sampling for events annotation
- Comparison between up to 3 recordings lets you get a better understanding of differences in HRV under different contexts in a glance. The comparison modality includes also Outlier removal
- Activity tracking: step counter or accelerometer derived motion intensity for user context (step counter only for iPhones 5S)
- Location tracking, either using GSM/WiFi networks (low battery consumption) or GPS (high accuracy)
- Configurable time window for features computation (choose between 30 seconds, 1, 2 or 5 minutes)
- RR-intervals correction can be enabled to prevent ectopic beats or artifacts from affecting HRV features
- export for Kubios
- Filters data based on the selected threshold
- Shows HR in the app icon
- Data export using iTunes or Dropbox
- Tested for recordings longer than 24 hours

Please note that continued use of GPS running in the background can dramatically decrease battery life.