Check out the Stress graph. High Stress = Low HRV and vice versa.

Thanks you!

trux said:

High Stress = Low HRV and vice versa.

This is 'kind of the rule of thumb', but it's not always the case.  Here's a couple of examples of the "vice versa' where a high HRV doesn't equal low stress or doesn't mean it's a sign of good health.

Mistake 2 – Assuming A High Reading Is Always Good

• If an individual is in a state of hyper recovery, their HRV can be abnormally high. When the body accumulates too much stress to the point where it can no longer effectively handle the stress and resources are depleted, the body might force itself into a hyper-recovery mode as a last resort to protect itself. This state is not ideal for long-term health or performance.

• Continuous low grade stressors can cause HRV to be higher in the short term because the body is constantly trying to recover from them. If your HRV is high but you frequently feel fatigued or drained, then you might be exposed to chronic low grade stress that is constantly stealing energy and resources from your body. This is not ideal and over the long-term, if these accumulated low grade stressors are not dealt with, they can eventually cause HRV and health to decrease.

Unfortunatelly, the Stress data is the closest we have for evaluating the HRV. The raw HRV data is not being stored in any FIT files (hence not transferred to GC) - neither in the monitoring files with the HR, nor in the Activity files. It is only used in real-time on the device for the calculation of Stress, VO₂max, and for other features, but only the Stress data is usable for the purpose requested in the OP (the estimation of HRV).

However, for the exact reasons you named (and for more of them that you did not list), viewing the Stress data is definitely nuch more preferable than evaluating directly the raw HRV data, since the Stress graph, processed by Firstbeat algorithms, already takes all these aspects in the consideration.

trux said:

, viewing the Stress data is definitely nuch more preferable than evaluating directly the raw HRV data, since the Stress graph, processed by Firstbeat algorithms, already takes all these aspects in the consideration.

I don't follow you.  The stress data Garmin/FirstBeat provides comes from HRV and HRV alone. 

What Is the Stress Level Feature on My Garmin Device?

I also have an Apollo Neuro device which is designed to improve HRV. It seems to work. At least I have seen improvement in time of deep sleep which had been poor. This has improved my overall stress level, although it was already pretty low due to my exercise regimen. But to get back on topic, I have been studying Apollos literature on HRV trying better understand how it works. From what I have read the measurement of HRV is very complicated and various sources measure it differntly. THis is a link to some articles: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4104929/   I agree with trux that raw HRV data would not be useful to the device user

Thanks for the link. There is also a whitepaper on HRV and Stress+Recovery, directly from the supplier of the algorithms Garmin is using in their devices - Firstbeat Technologies (now belonging to Garmin too): https://assets.firstbeat.com/firstbeat/uploads/2015/10/Stress-and-recovery_white-paper_20145.pdf 

bobchappuis said:

I am having trouble finding out how to use this to determine HRV.

bobchappuis said:

 I agree with trux that raw HRV data would not be useful to the device user

? 

Having a quick look at the paper hoping to find a formula that I could invert it seems that it's not a straight forward algorithm. It's a neural network :(

No chances of finding an inverse formula from stress to mean hrv