The HLTH Journal·The Science
HLTH Band: science and clinical accuracy
Most wearable companies lead with marketing. This page documents how the band was tested, what the numbers showed, and where the limits are.
HLTH Science Team· May 2026 · 4 min read
If we cannot prove it, we do not claim it. If you want to know how we know what we know, this is the page for you.
Our accuracy study: HLTH Band against the Polar H10
Bland JM, Altman DG. Lancet. 1986;327(8476):307-310We ran a 30-day paired accuracy study comparing the HLTH Band against the Polar H10 chest strap, a device widely used as a reference standard in clinical and sports science research. Twelve adults, ages 24 to 51, wore both devices simultaneously across four measurement conditions. In total 1,440 paired data points were collected and analysed using Bland-Altman analysis and Root Mean Square Error. Resting heart rate, measured in the morning lying still, showed a mean bias of +0.8 bpm, an RMSE of 2.3 bpm and an R² of 0.97. Active heart rate at moderate intensity showed +1.4 bpm bias, 3.1 bpm RMSE and an R² of 0.94. Active heart rate during high-intensity intervals showed +2.9 bpm bias, 5.4 bpm RMSE and an R² of 0.88. Overnight HRV, as RMSSD during sleep, showed a mean bias of -1.2 ms, an RMSE of 3.6 ms and an R² of 0.93.
What the HLTH Band measures
Every metric the HLTH Band tracks is processed through FlowSense Technology, our sensor processing layer. FlowSense adjusts sampling rate and signal processing in real time, maintaining accuracy during movement while extending battery life to 30 days. On the heart and cardiovascular side, it tracks heart rate, HRV as RMSSD, blood pressure and blood oxygen. For sleep, it tracks sleep stages across light, deep and REM, a sleep score, wake detection and overnight HRV. For activity and movement, it tracks steps, distance, calories, more than 30 sport modes and smartphone-tethered GPS. For recovery and stress, it produces a daily recovery score, stress levels, a readiness index and fatigue analysis.
Research highlights
Flatt AA, Hornikel B, Esco MR. J Sci Med Sport. 2017;20(6):606-610Our first accuracy study established baseline performance data across resting, active and sleep conditions. Resting heart rate produced an R² of 0.97 against the Polar H10 reference standard, and overnight HRV produced an R² of 0.93. Further studies across clinical populations, sleep conditions and athletic cohorts are currently underway.
Your data stays yours
The HLTH Band collects and stores health data in full compliance with GDPR. You control what is stored, what is shared, and what is deleted at any time through the app. No data is sold to third parties. Full data export is available on request.
