Why Does HRV Require a Chest Strap?

Heart Rate Variability (HRV) can only be masured by looking at the inter-beat variation of the R-R interval of the electrical signal from the heart. The electrical pulse signal has clearly defined peaks that enable this variation to be accurately measured.

The Oura ring, Apple Watch, (and Garmin watches with WHR) can estimate HRV by looking at Pulse Rate Variability (PRV). This is an estimation based on an analysis of the colour change of the skin as a pulse of blood transits through the veins. This is a sinusoidal waveform without a clearly defined peak.

Most Garmin watches with WHR use estimates of PRV to derive Pulse OX, Stress, breathing rate, and HRV when rested, although you do have to have a strap to take a static measurement during wake times. I think I am correct in saying that even the watches you reference do not provide HRV during exercise.

I would be thrilled to be able to just get an accurate overnight reading. I don't think the fenix/delta does this? And at least oura seem to think their methodology is damn accurate and provide data to back it up

"How Accurate Are Oura's Heart Rate & HRV Measurements? - The Pulse Blog" blog.ouraring.com/.../

any heart rate device should be able to give you a number it claims to be HRV. HRV during exercise is not accurate from oHR. HRV at rest is accurate enough fro many devices.

Check this out about Apple Watch HRV:
https://medium.com/@altini_marco/how-to-make-sense-of-your-apple-watch-heart-rate-variability-hrv-data-89bf4a510438

Estimate or not - it's great on Apple Watch.

Marco Altini is THE world authority on HRV, so  I would defer to whatever he says about it.

I've not read in detail that article but the Apple Watch uses the BREATHE app to take a resting HRV reading and that's pretty accurate in itself. point being...you sit still and don't move for a minute or so.

That said, even if you take an accurate HRV reading..so what? It only means something when you have the context in which it was taken. Think about that point as it is one of the keys to better understanding HRV.

ok so can we ask marco atini why garmin is requiring a chest strap to measure a metric that their competitors seem to be able to measure with stunning accuracy without one?

support.garmin.com/.../

I can be wrong, but I remember I’ve had to stand still for 30 sec (?) to take a HRV reading with HRM Dual + Fenix 6X Pro, so exactly like AW.

AW takes HRV readings during a day, when you’re not moving to much, You can force it with the Breath app.

There’s a great app called Training Today, that shows you the readiness to train based on HRV, Resting HR and a bunch of stuff. I can say, it’s pretty much on point. It’s just a number and of course everybody should listen to their body, not an app, but it’s nice to see that it’s just working quite well.

so from what's been posted here and from info found elsewhere, it seems that garmin watches do indeed track hrv and the data is used as a component in a great many metrics, but this hrv data isn't available to users, though there are apparently apps in the garmin iq store that can access the underlying data and present them to you

the hrv stress test app on the watch that requires a chest strap and asks you to be standing for some reason is a completely standalone function that doesn't influence any garmin metric. if you're truly interested in hrv metrics and training, this app is essentially a waste of time as it doesn't provide any meaningful data other than an overall stress score. missed opportunity, garmin...

Do any of the CIQ apps that incorporate HRV data offer any useful insights?

Question still remains why the HRV stress test requires a chest strap when all the other metrics using HRV gather those data from the wrist?