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Your heart rate climbing stairs

Ongoing studyRecorded on real stairwells, up and down

This is an ongoing study. The figure will be updated here as more people are recorded.

OPTICAL

Accuracy

91.8%

Stair Climbing Heart Rate Agreement

against an ECG chest strap worn up and down the same flights

Reference standard

ECG chest strap

Sample size

4 participants

Climbing stairs, the Ultrahuman Ring reads within nine beats a minute of an ECG chest strap, on average.

Ultrahuman RingECG chest strapbeats per minute
91.8%agreement with the chest strap
8.4 bpmaverage difference
72%of readings inside the ±5 bpm / 10% tolerance
57–159beats per minute the reference covered in study
Figure 1 — One continuous stretch from a single recording. The figures beside it are for the study as a whole, not for the stretch drawn.
-45-30-150+15+30+4560708090100110120130140150upper limit of agreement (+19.2)lower limit of agreement (-16.2)average offset +1.5 bpmthe two devices averaged (beats per minute)ring minus chest strap (beats per minute)
Figure 2 — Every five seconds, against the chest strap
One dot is one paired five-second reading, as recorded, pooled across recordings.

Stairs are a short, sharp effort, and that is the whole difficulty. Your heart rate can climb thirty beats in half a minute and fall most of the way back before you reach the next landing. An optical sensor averages several seconds of pulse to produce each reading, so on a staircase it is always arriving slightly late — and arriving late is hard to tell apart from being wrong.

The trace below shows that clearly: the two lines climb and fall together, with the ring a beat behind at each corner rather than adrift from it. Following the shape is the thing worth doing here; the average difference mostly measures the lag. Anyone can check it with a stairwell and a chest strap.