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Comment by cinntaile | Hacker News Reader

What's the reason that you can't use this ring for exercise? It feels like such an obvious feature to include so there must be some technical reason?

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It achieves low power consumption by being off most of the time. That works out just fine for sleep because sleep phases take a long time to change and to verify that you need to take multiple samples over long time periods. But to accurately track movement characteristics you need to be always on.

The instructions it came with tell you not to wear it while using dumbbells or barbells. As for cardio, I guess it's ok. Mine tends to say I took 20% more steps per day than reported by the pedometer app on my phone. I have no clue which one is more accurate though.

Guessing the extremely tiny battery has something to do with it. It's a bit like how Apple Watch's battery life tanks when you use it for exercising and I don't think the Apple Watch gives the most accurate/highest resolution readings.

I would assume that to achieve a 7 day battery life they only take rare measurements of your heart rate, which makes it unfit for the kind of high resolution heart rate tracking people are used to from fitness watches. They also mention that any sport which has a significant level of hand involvement might disturb the reading.

They do still track general intensity of activity though, which for general health is probably a more relevant metric than exact heart rate.

Indeed, the automatic HR measurement powers the heart rate sensor array only when the accelerometer reports that the ring is stationary, i.e. the user is likely sleeping. This also makes sense because hand movements tank the accuracy of the sensors anyway. With manual measurements, you can still only get useful data if you're using it to measure during meditation or rest.

Night-time PPG measurement of Oura ring IS high-resolution. PPG is measured only when you are still enough.

Activity tracking is based on accelerometer data.

The Oura only measures heart rate in five-minute intervals [1] while sleeping. A workout set/running interval could easily be completed within five minutes, making the measurement useless.

I've had many instances where my Oura failed to track heart rate while I was asleep, if the ring rotates, slides to a thinner part of my finger, or I am moving a little too much.

[1]https://ouraring.com/heart-rate-while-sleeping

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