Record properly
Record properly
Embedded Files
HRVA is an Android app that records heart rate variability live from a Polar H10 chest strap. I built it for sport-science research and teaching: clean RR-interval recordings, real-time HRV, and exports that go straight into your analysis workflow.
Why I built it
Why I built it
Consumer heart-rate and HRV apps tend to reduce a recording to a single “readiness” score and keep the raw data locked away. Lab software is powerful, but it usually runs after the fact, on a laptop. HRVA sits in between. It is a field-ready recorder for any kind of laboratory, whether a simulated lab room with a treadmill or stationary bike, an open field, or a pool deck, and every beat it records stays available for later analysis.
To carry that data from the recording to the analysis without losing anything, HRVA exports each session as a single encrypted .hrva file. One file holds the whole session: the beats, the markers and segments, the participant details, and the data-quality record. HRVA Workbench, a desktop app built specifically to analyse HRVA recordings, reads these files directly, so what was recorded in the lab arrives in the analysis complete and unchanged.
What it does
What it does
Records directly from the Polar H10
HRVA connects to a Polar H10 chest strap over Bluetooth and records every heartbeat as it happens: RR intervals, heart rate, and accelerometer data, with optional ECG at 130 Hz. Signal quality is checked continuously. Sensor disconnections and moments when the strap loses skin contact are logged automatically with the exact time, so you can see what happened during the recording rather than guess afterwards.
Real-time HRV
HRV is calculated on the phone while you record, and each metric appears once there is enough data for it to be meaningful:
Time domain: RMSSD, ln(RMSSD), SDNN, pNN50, mean RR
Poincaré: SD1, SD2, SD1/SD2
Frequency domain: LF, HF, LF/HF and Total Power. These follow the Task Force (1996) recommendations, using Welch’s method with a Hann window over a 5-minute window.
Short-term metrics such as RMSSD appear after about one minute. Metrics that need longer data, such as SDNN and the frequency-domain values, appear after five minutes.
Two recording modes
Stationary mode is for resting and positional protocols. You choose the participant’s body position (for example sitting upright, sitting inclined, supine, or prone) before the recording starts. Live ECG, HRV and Poincaré views show what the signal looks like as it is being recorded.
Activity mode is for treadmill and stationary-bike sessions. HRVA calculates a personal heart-rate target zone with the Karvonen method, from the participant’s resting heart rate and age. It then shows live time-in-zone and alerts with sound and vibration when the participant drifts below or above the target intensity.
Markers: annotate the session as it happens
During a stationary recording, the researcher can tap to add markers, all time-stamped to the recording:
Events: numbered markers (Event #1, #2, …) for anything worth noting, such as an instruction given, a cough, or a door opening. Numbers are never reused or reshuffled, so a note written on paper during the session always matches what the app shows.
Position changes: when the participant moves, for example from sitting to lying down, you record the new position at the moment it happens.
Some markers are written by the app itself, never by a tap: Bluetooth disconnects and reconnects, loss and return of skin contact, and transitions in signal stability detected by the app’s own algorithm. They are kept separate from the researcher’s markers. That way you can later compare when you thought the participant was settled with when the signal actually was stable.
Segments: mark the stretches you want analysed
A recording often contains more than the part you care about: settling in, instructions, movement between conditions. With Begin segment and End segment, the researcher marks the stretches of the recording that are meant for analysis, for example the final five minutes of a resting baseline. Segments are numbered (Segment 1, Segment 2, …), and you decide whether a segment is already running when the recording starts.
Segments are your intent, recorded alongside the data. Nothing is cut or thrown away. The full recording is always kept, and every export says which parts fall inside a segment.
Participant management
A built-in participant registry keeps every participant and their sessions together:
Each participant has a name or code, age, sex, resting heart rate, and training status (athlete or sedentary).
An overview grid shows the participants by sex and training status, plus the total number of sessions and hours recorded.
You can search by name or code, sort by name, most recent session, or age, and filter the list.
Opening a participant shows their full session history.
Session Summary
When a recording stops, HRVA produces a Session Summary report:
Session details: participant, sensor, duration, start and end time, body position, and recording mode.
Heart rate: resting and maximum heart rate, plus mean, minimum and maximum heart rate during the session.
HRV table: each metric with its value at the start and end of the session, and its minimum and maximum.
Activity mode: intensity adherence and time spent in each of five intensity zones, from very light to near-maximal.
Markers: every event, listed with its time.
Recording notes: an honest account of data quality. It covers Bluetooth disconnections, skin-contact loss, sensor battery at the start and end, and warnings when a session is too short for some metrics to be reliable.
Session notes: free text added by the researcher.
The summary can be saved as a PDF, and every report states the methods behind its numbers.
Export for analysis
Every session can be exported as:
a PDF summary;
CSV files with the raw and calculated data;
rr.txt, ready to open in Kubios HRV;
one encrypted .hrva file per session, for analysis in HRVA Workbench.
Use Cases
Resting HRV baselines
Record a participant’s HRV at rest in a standardised position (sitting upright, sitting inclined, supine, or prone) before a study condition, a training block, or a test day. Mark the minutes you intend to analyse as a segment, for example the final five minutes after a settling period, and export rr.txt straight to Kubios HRV, or the .hrva file to HRVA Workbench.
Pre–post designs
Measure the same participant before and after an intervention, such as an exercise bout, a breathing exercise, a cold-water exposure, or a recovery strategy. The Session Summary shows each HRV metric at the start and end of the session, and the participant registry keeps every session of every participant together, so repeated measurements stay organised.
Position-change protocols
Follow how heart rate and HRV respond when a participant changes position during one recording, for example from supine to sitting. Each change is recorded as a time-stamped position marker, and the full recording is kept, so the transition and the stable periods on either side can be analysed later.
Exercise sessions in the lab
Record during treadmill or stationary-bike work in Activity mode. HRVA calculates a personal target heart-rate zone with the Karvonen method, shows live time-in-zone, and alerts with sound and vibration when the participant drifts below or above the target intensity. After the session, the summary reports intensity adherence and time spent in each of five intensity zones.
Field and poolside measurements
A “laboratory” is not always a closed room. HRVA is designed for open fields and pool decks, where the phone may be far from the participant. Bluetooth disconnections and loss of skin contact are logged automatically with their exact times. A recording interrupted by distance is therefore documented as interrupted, not silently presented as complete.
Teaching
In practical classes on exercise physiology or the autonomic nervous system, students can watch the ECG, RR intervals, and HRV metrics update live on the phone. They see directly how breathing, posture, or movement changes the signal, and they can take the exported data into their own analysis.
Multi-participant studies
Register participants with a code instead of a name, record their training status (athlete or sedentary), and filter or search the registry as the study grows. Each session’s encrypted .hrva file carries the recording and its markers into HRVA Workbench for analysis across participants and conditions.
What HRVA is not for:
clinical diagnosis, monitoring of patients, or any medical decision. See Privacy & disclaimer below.
Privacy and Disclaimer
Your data stays on your device
Recordings and participant details are stored only on the phone. HRVA has no internet access, sends nothing to the developer or anyone else, and is not included in Android/Google backups. The .hrva export is encrypted.
Files you export or share (PDF, CSV, rr.txt, .hrva) leave the app’s protection. Keeping them safe is up to you.
Using HRVA in research
HRVA is a recording tool. It does not replace your study’s ethical procedures. If you use HRVA for research, you are responsible, under your own research protocol, for:
obtaining informed consent separately from every participant, before any recording;
obtaining ethics approval where your institution or country requires it;
using participant codes instead of names where your protocol requires it. Never write participant names in session notes or event descriptions, because these are included in exports.
HRVA does not collect, store, or verify consent on your behalf.
Not a medical device
HRVA is intended for sport-science research, teaching, and wellness monitoring only. It is not a medical device and does not provide medical diagnoses. Results have not been validated against clinical-grade ECG. Consult a qualified healthcare professional for medical decisions.
Page updated
Google Sites
Report abuse