Featured
Heart Rate Variability
The variation between your heartbeats, and what the research says it reveals about recovery.
Read the guideThe ScienceHeart Rate Variability
The variation between your heartbeats, and what the research says it reveals about recovery.
The ScienceWhat is heart rate variability? A complete guide to HRV
A heart that changes its rhythm slightly with every beat is a healthy heart. One that beats like a metronome is a heart under stress.
The ScienceHow the HLTH Band measures HRV, and what our accuracy study found
A number that does not reflect what is actually happening in your nervous system is worse than no number at all.
The ScienceHow the HLTH Band measures HRV continuously
A morning check tells you how you recovered overnight. It tells you nothing about the rest of your day.
The ScienceHLTH Band Accuracy Report: how we tested it and what we found
A 30-day paired study against the Polar H10 chest strap. The full methodology, the results, the statistics and the limitations.
The ScienceHLTH 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.
Get the science, without the noise
Occasional emails on heart health, sleep and recovery. No hype, unsubscribe any time.