Are Cardio Fitness Scores Accurate?

[BillyDB]

Hi, I'm a male in my late 60s. Been using a Charge5 for a few years. My cardio fitness scores are relatively stable 49 - 53 to 51 - 55 ranges. Thing is, I haven't focused on aerobic training for a number of years and generally suck wind when I do engage on occasion. These scores, however, put me in rare VO2 Max territory on a percentage basis which makes them hard to believe. Can anyone shed any light on why my scores might be so high and why and how much I should trust them?

[JohnnyRow]

My interpretation: unless you do a few of those those 10+ minute runs with GPS (which give you an exact number rather than a range), the fitness score is really just an estimate, but still worthwhile for looking at the trend.  For instance, I have an "excellent" score, but this is because I have an abnormally low resting heart rate, lower than my heart doctor would prefer, but not because I am in great shape.

[9422]

When Fitbit/Google came out with the Charge 6 they advertised heart rate monitoring was 60 percent more accurate. 
What does that tell you about Charge 5 and previous versions?

[BillyDB]

Thanks Johnny Row! I too have a relatively low resting heart rate, am fairly light for my height and in my late sixties. Though probably above average in cardio fitness, still not exceptional. Will try running a few workouts with GPS on. Running is sport specific though and I'm likely better than whatever results from that. Would do better with a trained movement than an untrained one. Anyway, as you say, even if the absolute measurement is overstated, the stat can still be useful on a relative basis.

[JohnnyRow]

Lighter weight I think is also a factor that would give you a higher calculated fitness score.