Cardio Fitness Score (CFS) versus Heart Rate Variability (HRV)

[Ozzielicious]

According to Fitbit research, a higher HRV is linked with better health, while a drop is a sign of illness. Further readings also mentions that physical activity is a contributor to HRV, and “people with a higher HRV have a better cardiovascular fitness and […]”. Similarly, a higher CFS is also an important metric of better health. The significance of a higher CFS and its benefits are stated abundantly. 

My HRV has mostly been poor in the 20-30’s while my CFS has persistently been in the excellent category (wearing Charge 4 since Dec 2020).

So why does my data contradict the research for men in the same age group? Perhaps more factors are to be considered? For example, in my case, I run 5 days/week ~40 mins, however I sleep an average of 5 hr 30 min a day. My physical activity contributes to my 'excellent' CFS and VO2, while my sleep degrades my HRV score. I am not a health professional, and this is merely my inference. The research is no doubt, very misleading!

Moreover, my resting HR dips as low as 42 bpm just before my alarm goes off in the am, but unfortunately the graph does not get enough time to display its lowest potential. I believe the RHR metric considers the average HR when asleep My HR graph is always downwards sloping, giving me a fair reason to assume that it would continue to dip if I slept for over 5.5 hours. 

[JohnnyRow]

"My HRV has mostly been poor in the 20-30’s while my CFS has persistently been in the excellent category (wearing Charge 4 since Dec 2020)."

Note, I dont' think your classification of HRV 20-30's as poor is from Fitbit.  I haven't noticed any Fitbit HRV ratings.  Apparently you got that classification from some other source.  Fitbit's description of HRV says that many things can affect your HRV, and seems to imply that it is more valuable to be looking at trends within your usual HRV range.

I'm not saying your source is wrong, but perhaps there are differences is how it is measured and calculated, making it more useful to be looking at trends from the same measurement source.

Or maybe you are right and the #s just don't make sense.