Loading...
Pre-order nowPre-order now

Your heart rate through a hard interval

A hard interval and the recovery after it
OPTICAL

Accuracy

90.1%

HIIT Heart Rate Agreement

compared with an ECG chest strap across the same intervals

Reference standard

ECG chest strap

Sample size

43 participants

Through a hard interval and the recovery after it, the Ultrahuman Ring stays within thirteen beats a minute of an ECG chest strap, on average.

Ultrahuman RingECG chest strapbeats per minute
90.1%agreement with the chest strap
12.2 bpmaverage difference
+4.1 bpmthe ring reads high, on average
73–177beats 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. Average difference tells you how far a typical reading is from the reference, regardless of whether it is high or low. Average offset tells you the direction of that gap — whether the ring reads high or low, on average.
-45-30-150+15+308090100110120130140150160170180190upper limit of agreement (+32.6)lower limit of agreement (-24.4)average offset +4.1 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.

Intervals are designed to make your heart rate move as fast as it possibly can. A hard effort drives it up by dozens of beats in well under a minute, and the recovery pulls it back down almost as quickly. An optical reading is smoothed over a few seconds, so the faster the number is travelling, the more work it takes to stay on it. What this card asks for is a quick reading rather than a steady one.

The trace below is one hard block. It opens at an easy pace, jumps as the effort lands, holds through a working stretch, then climbs hard towards the top. The Ultrahuman Ring reproduces the whole shape, corners included.

Where a difference opens up at all, it is on the steepest ramps, where the number is travelling fastest, and it closes again on the plateaus either side. A gap that opens on the ramps and closes on the plateaus points to a reading following the change rather than one that has drifted off it.