Edited Note: I don’t know a thing about Elite HRV, so if your comments are specific to that particular app, then read on at your leisure. My comments are about HRV’s usefulness in general, and are solely my opinions on the matter.
I think you’ve got your thinking turned around 180 degrees from what’s largely accepted by long-term practitioners with HRV. Specifically, day-to-day measurements aren’t going to be nearly precise enough and the conditions are going to have variable inputs that can change the absolute values on a day-to-day basis.
So, you might look at raw numbers like rMSSD and resting HR, but if you’re doing the single one-minute measurement in the morning, are you certain all the factors are controlled for such that your 66 shows that you’re fatigued and need rest where your 75 shows you are ready to go? And how do you feel? If you’re taking RHR, when is that measurement taken… under what circumstances? Do you pull the plug on training if you have a RHR of 45 in the morning, but train if it’s a 44? What if you had a beer the night before or went to bed a little later?
Longer term trending shows how you’re adapting to your training program. If you look over the course of a four-week block, you might start with a higher absolute value, and then watch it degrade over time as you fatigue (or in my case, you might actually see an opposite trend, where coming out of recovery I’m almost always low, and as I build through a training block my HRV drives higher and higher, and so does my RHR all things held equal).
The bottom line with using HRV is that the science supports longer term trend analysis far more than day-to-day acute values. Day-to-day values may or may not be actionable, and for that you should ask your coach/doctor/whomever you trust. I have my opinion, it’s stated above, but I’m certainly not going to tell you what you should do with your own stuff.
I would just caution you to be aware that the people who are telling you HRV is good for day-to-day and touting “Readiness Score”, “Recovery Score”, and “Body Battery” are all trying to sell you an expensive gadget. (And not all methods of gathering HRV data are equally precise/accurate).
In my opinion - formed on reading some research and having been an HRV practitioner for nearly a year as well as looking at other athlete data - HRV is not particularly useful for making acute, day-to-day training decisions; HRV IS useful when “something else” is going on - I think it is a good indicator of stressors other than your training (e.g. “life”, illness, etc.); HRV is useful in looking at overall adaption to training in macrocycles. Again, that’s just my personal opinion. I am open to science showing me otherwise.
For the record, I have done HRV with both a Polar H10 and now measure HRV along with other biometrics via my Oura. I don’t use the “readiness score” from Oura nor raw data from HRV4T or Oura to make training decisions on a day-to-day basis, but I do use them in the other ways I described above.
As always, YMMV.
Maybe this one will show something different/interesting. I suppose it completely depends on the training and what adaptations they’re seeking.