Cardio algorithm

Kris said:

So, I think there is some problem with the cardio algorithm related to the reading from the wrist.

I do not think there is anything bad with the algorithm (my Instinct reads my HR fine up to ~200bpm during activities), rather with the fit, or perhaps with your physiology/physiognomy. The OHRM is quite sensitive to the proper fit on the wrist. Also factors like skin thickness, skin tan, tattoos, body hair, the haemoglobin level, periferal vasoconstriction, or other medical conditions will influence the reading. You may try cleaning the sensor, adjusting the fit of the wristband, assuring a quite firm contact of the watch to the skin, though without cutting the bloodstream. You can try the other wrist, the inner side of the wrist, or even the ankle (just ot see if it helps).

Read also the Support document The Heart Rate Sensor on My Watch Is Not Accurate

If nothing helps, then it likely means that you are one of those unlucky individuals for who the OHRM has a quite limited functionality, and you'll need to use a chest HRM.

Thanks trux.

I have my instinct since 2018, when just released. I know well my whatch and I’ve never had this kind of problem. I think that if I train without starting any activity and the heart rate in 120, but it is 90 just after starting cardio (2 seconds after...) there is something wrong somewhere.

I would underline that the problem there is only with the app cardio. All the others apps work fine.

Anyway I’ll tray with a reset o wait the next update, maybe I’ll be lucky!

thanks again

Kris said:

if I train without starting any activity and the heart rate in 120, but it is 90 just after starting cardio (2 seconds after...) there is something wrong somewhere.

I'll test it, but the most likely reason is that during the cardio exercices you move your arms, which has the impact on the watch adhesion and the pressure to the wrist, and also, it modifies the bloodstream in the arm, which then can easily cause false readings. That's why I suggested trying it for example on your ankle, instead.

Kris said:

I would underline that the problem there is only with the app cardio.

OK, so I tested it, and as expected, the algorithm is fine even when using the Cardio Activity. I tested on a stationary bike - pedalling in a steady rythm at 120bpm, first without any Activity selected, then with the Cardio Activity, then without it again, to cross-check it, and then with the Indoor Cycling Acitivity selected - in all modes Instinct continued reporting ~120 bpm. I tried it both with the watch on the wrist, and on the ankle - same result.

I do crossfit and most of the exercises involve a lot of wrist movement. Treadmill and indoor bike are an easy job for the OHRM but for anything else I think that a HR strap is obligatory 

darnich said:

for anything else I think that a HR strap is obligatory

It is reallly strongly individual. For me the OHRM works reliably practically in all situations. But otherwise, yes, that's exactly what I wrote - the arm motion can cause false readings, if the fit, the skin tone, haemoglobin, vasoconstriction, and the general state of veins are not optimal. In that case changing the position, using the ankle, or chest belt HRM are better options.

However, that is not a problem of the algorithm as claimed in the OP, but a limitation of the OHRM.