[blairbeckwith]

I think you're probably right on a lot of this.

I do think the pace having more granularity than five seconds is important for anyone who's doing any kind of speed work, where a pace off by 5 seconds can result in a fairly significant variance. Admittedly I am not a total novice, but my 5k and 10k pace times are about 10 seconds apart, and I do some interval workouts at 5k pace and some at 10k pace. 5 second granularity doesn't give much wiggle room there! Although of course, GPS and cadence-based paces are also estimates, so maybe the 5 second accuracy is better than 1 second which could inpsire a false sense of confidence in the estimate.

As far as Vo2Max goes, totally agree – my lab test results vary widely from both watches. However, I think that actually makes Apple's 1 decimal place more significant – it has a lot of value in offering a fitness trend, even if it's inaccurate. I might train hard for 3 weeks and see 0 movement in my Garmin Vo2Max, whereas I might see a 0.3 increase in the Apple Watch. This is valuable for even the novice runner.

[015a]

I feel the important piece to remember with VO2Max estimation is: Its an estimation. Its significant figures [1]; reporting the value to one or more decimal places communicates a level of confidence inappropriate for how inaccurate these estimations generally are. Especially the Apple Watch's; Garmin's is known for being pretty decent, usually +/- 2, but Apple Watch's is all over the place and is infamous for being really inaccurate.

Clamping pace to 5 seconds is a similar idea. GPS isn't super accurate: within 16 feet some sources say [2], though it gets better if you've got dual band, if you're moving; but it gets worse when you don't have an open sky. Just ten feet of GPS inaccuracy over a ten minute mile means your recorded pace is somewhere between 9:58/mile to 10:02/mile. And, experimentally, these systems are way, way more inaccurate than that: on a recent bike ride, with no major sky obstructions, I wore both an Apple Watch Ultra 2 and Garmin Enduro 3; the AWU2 recorded 25.05 miles, Enduro 3 recorded 25.18 miles. That's a difference of ~686 feet; ~27 feet/mile.

[1] https://en.wikipedia.org/wiki/Significant_figures

[2] https://www.gps.gov/systems/gps/performance/accuracy/

[pertique]

That's very true, and I'd love to see some actual documentation on how they get to pace numbers.

I'm in the same boat with regard to 5K/10K pace, but I reckon it's probably not a huge issue in the long run. While plans specify those times, I think it's more about shorthand for effort zone where 5K is "this hard" and 10K is "a little bit less hard".

VO2 max improvement is a good point, though, and I'd probably agree. If I had a hazard a guess, Garmin would say that their training productivity tracker/race estimated are the preferred way of presenting that data. as an aside, I think VO2max has sorta been coopted as a "fitness number" when it actually represents a very specific thing that may or may not be emblematic of actual performance in the majority of cases. It is nice to have a a single value to look at that can sum up whether what you've been doing lately is productive, though.

That could just be me coming from the world of cycling where watts are king and there's far less variability. In my mind, all these running stats are mushy, but that might not actually be the case.