Thanks for your replies! I should just go and state that I don’t use the Garmin metrics in my training and planning. I use the Fitness, Form and Fatigue scores from intervals.icu along with my Training Plan. My point to the original poster was that I don’t see the same behavior he mentions about being way off or conflicting, my experience is that Garmin lines up very closely to intervals.icu.
My statement about the more data you feed it, the more accurate it is, was more a general statement to people who use Garmin and say the metrics are crap and way off. I don’t see it, and often when you dig in to what they are saying they are using some other cycling headunit or indoor app that doesn’t even get considered for Garmin metrics, or they don’t wear the watch 24/7, or they are using wrist based heartrate, or they don’t understand what certain Training Statuses mean and get offended by what it reports, or they are massively overtraining, or flip side, doing way less than they believe they are.
I used EliteHRV for awhile and am embarassed to say I stopped because I didn’t understand it enough to make it meaningful. I wish I did, I’ll read that paper you posted.
“I have often argued that provided you know what you are doing, morning and night measurements are equivalent in the long run.”
" In the latest paper looking at this exact question, “Evaluation of nocturnal vs. morning measures of heart rate indices in young athletes”, Christina Mishica and co-authors report that “heart rate and RMSSD obtained during nocturnal sleep and in the morning did not differ”."
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Andrew Flatt has also stated the same, tho I can’t find the source just now. Both morning and nighttime HRV tracking work, as long as one understands the differences, especially when considering the trends over time.
Personally, I can consciously fool morning readings which makes them useless for me. I rely on nighttime HRV and I can say that both the trends and the variations are consistent with my personal wellness evaluations and an underlying condition that predisposes me to parasympathetic hyperactivity.
Just be aware that they can be quite different if you have the habit of working out late with little time between end of workout and bedtime!
In that case, the overnight HRV measurement will be strongly influenced by the first phase of recovery while a morning measurement will be much less impacted.
Oura performs better than watches: it doesn’t measure from the wrist, and it measures continuously throughout the night, whereas garmin and apple only take some random samples (which produce worthless data).
Once again, if you like wearables, they can clearly capture high-quality HRV data as we sleep. Just make sure to use one that gives you the full night of data, as otherwise HRV measurements won’t be reliable (as I discuss in greater detail here). My recommendation would be the Oura ring for this exact reason: most other sensors will provide automatically collected sporadic data points (e.g. 5 minutes during the night, like the Apple Watch does), which unfortunately are noisy and do not reflect underlying physiological stress very well.
I’m not sure there’s a great difference in how Oura and Garmin devices sample overnight HRV.
From Garmin:
Compatible Garmin devices calculate HRV continuously while you are sleeping. When you wake up, you can view your average HRV calculated using data from the entire sleep period. You can also review a chart that shows how your HRV changed while you were asleep based on analysis of 5-minute time windows.
From Oura:
The average HRV you see is the mean of all five-minute samples taken while you sleep. Oura accounts for changes in your HRV every five minutes throughout the night, instead of just once at a single point during the night.
Personally, I measure HRV daily, shortly after rising using HRV4Training - though I keep an eye on what my Garmin watch says.