Conteúdo do Tutorial / Guia Passo a Passo:
-------------------------------------------------------------------------
My partner and I have this thing where we check at what time our heart rates drop to their lowest during sleep, even though we sleep almost at the same time for a similar duration. He's on a Garmin, while I track mine with the Ultrahuman Ring AIR.

I know you must be thinking that doesn't make sense: two different people are never going to have the same heart rate numbers anyway. Different resting baseline, different fitness levels, different everything. And yes, that part has nothing to do with wearables at all. But it's almost a competition at this point.

The real question here arises when you take the comparison of the same heart rate metric with different wearables but on the same person. The heart rate reading will be different – again because it will depend upon the type of sensors used in each case, the speed of sampling, and the software algorithms of the sensors.

After you learn how they work internally, you'll finally be able to understand why the numbers are different.

Table of Contents

• They're All Measuring the Same Thing, Just Not in the Same Place

• Why Your Heart Rate Isn't Constant

• Sampling Speed Changes What the Device Actually Catches

• The Algorithm Matters as Much as the Sensor

• Skin Tone and Wrist Size Add Another Layer

• Activity Type Throws Everything Off Differently for Each Brand

• What This Means If You're Comparing Numbers With a Friend

They're All Measuring the Same Thing, Just Not in the Same Place

All of the wearables worn on your wrist or finger use the same technique known as photoplethysmography (PPG). An LED shines light into your skin while a sensor measures how much light bounces back with each heartbeat. The technology remains the same among all manufacturers, but the difference here lies in the place of measurements.

Finger-based wearables measure arteries located closer to the surface of the skin than the ones on your wrist. This gives finger-based devices like the Oura Ring a real advantage.

This advantage becomes clear even in the sleep stage, since the movements of your fingers are smaller than the movements of your wrist during sleep. Research done to test the accuracy of the heart rate reading by the Oura Ring has been able to show high consistency with the ECG measurements.

This is one reason Oura tends to perform well in nocturnal heart rate verification. A comparative study conducted in 2025 in the journal Physiological Reports pitted 5 devices (the Oura Ring Gen 3, Oura Ring Gen 4, Whoop 4.0, Polar Grit X Pro, and Garmin Fenix 6) against a medical-grade ECG for 536 nights of sleep. The Oura Ring 3 and 4 correlated the most accurately with ECGs, WHOOP correlated moderately, and Polar had the lowest accuracy.

Why Your Heart Rate Isn't Constant

One thing you need to know is that your heart rate isn't constant even at rest.

It varies all the time with your breathing movement or any other stress response, even when you're sitting completely still. 68 bpm can become 72 bpm after just a few seconds and nothing out of the ordinary happened.

It's enough for two wearables to have slightly different readings just because they were measuring at different times. Before sensor location, sampling rate, or any other algorithm comes into play, what's being measured is already constantly changing.

Sampling Speed Changes What the Device Actually Catches

Position of the sensor is impor

... [O tutorial continua no link abaixo] ...