Loading...
Pre-order nowPre-order now

Your heart rate coming down after a hard effort

The minutes after a hard effort
OPTICAL

Accuracy

96.1%

Exercise Recovery Heart Rate Agreement

scored against an ECG chest strap through the minutes afterwards

Reference standard

ECG chest strap

Sample size

43 participants

Through the minutes after a hard effort, with heart rate falling fast, the Ultrahuman Ring stays within six beats a minute of an ECG chest strap, on average.

Ultrahuman RingECG chest strapbeats per minute
96.1%agreement with the chest strap
5.6 bpmaverage difference
+1.7 bpmthe ring reads high, on average
95–181beats 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.
-30-20-100+10+2090100110120130140150160170180190upper limit of agreement (+15.5)lower limit of agreement (-12)average offset +1.7 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.

The minutes after a hard effort are the fastest a heart rate moves on its own. The work stops and the body starts unwinding it: the nervous system’s brake, held off all the way through the effort, comes back on within seconds, and the heart begins doing the same job with fewer, fuller beats. A rate sitting near its maximum can shed 60 beats a minute or more before the breathing has settled. Catching that from a finger means reading a pulse that is changing underneath the reading: the vessels are still wide open from the effort, the skin is warm and flushed, and the number has to be caught on the way down rather than once it has come to rest.

The trace below is one recovery. It opens near the top of a hard effort, climbs a little further to its peak, then falls away by 68 beats a minute as sitting still takes over: steep at first, then flattening into a long tail. The Ultrahuman Ring holds the shape of it throughout, and closes on the reference as the fall slows — its gap through the second half of the descent is under five beats a minute.

Across the recoveries measured here the ring and the chest strap agree to within six beats a minute, over falls of 63 to 75 beats a minute. A little more of the difference sits on the steepest part of the descent than on the flat tail underneath it, which is what a reading that keeps up with the fall costs. The window also sits high on the scale, where a given error in beats is a smaller share of the reading than the same error at rest.