Lacking congruence.

LaudelinoQ said:

Here is an example: the race forecast gives me an estimated time of 52:54 for 10k, while the coach's plan tells me that it is unlikely that I will finish the 10k in 57:00.

I think the race predictor is based on your VO2 Max and training history (and for event-specific race predictions, environmental factors for the event), while the Garmin Coach Confidence Score seems to be based on whether you're meeting your workout targets during the plan.

The inconsistency does sound annoying, but maybe it's unavoidable (since it's two different methods of predicting your performance).

In this case, it seems that your predicted race result based on VO2 Max is much faster than your workout performances would suggest.

One explanation could be that maybe your VO2 Max is overestimated (perhaps due to max HR being set too high?)

Or maybe you are underperforming during workouts for whatever reason? Sometimes I have bad workouts (for various reasons) and my VO2 Max goes up anyway, probably since my HR is super low during these workouts.

Another explanation is that neither prediction can be taken completely seriously.

Anyway, I've never taken the VO2 Max estimate or race predictions too seriously (although the race predictor has improved a lot in the past few years). I try to focus on the trends rather than the absolute numbers.

While I consider Garmin's predictive model to be erratic, I am surprised that Runalyze has established an average VO₂max value of 33 ml/kg/min over the past month, with an estimated 10 km time of 58:35 minutes (a value highly correlated with my performance). In contrast, Garmin reports a VO₂max of 46 ml/kg/min and an estimated 10 km time of 52:56 minutes.

I always find runalyze's vo2max estimation to be a lot lower than Garmin's - by about 10-12 points. In the past, when Garmin's race predictor was just a lookup table based on VO2 Max, this meant Garmin's race predictions were much faster than runalyze's. Now that Garmin also takes training history into account, its predictions seem a lot more realistic to me (only slightly faster than runalyze.)

I do like the fact that runalyze has a VO2 Max correction factor based on your actual race performances.

Interestingly , my RA and Garmin VO2 are almost the same ( to fractions of a digit) , and have been well aligned over the past month, My RP for a recent race over 5km with the route map loaded was with 10secs of the time I ran on the day. 

Kind of interestingly to me, if you compare the VO2 Max "running tables" (lookup tables going from VO2 Max to race prediction) and the Garmin lookup tables (as reverse-engineered from FR620), they're not aligned (e.g. the old Garmin race predictions for a VO2 Max of 46 roughly correspond to 43 in the runalyze table.). Ofc this is probably less relevant now that Garmin corrects race predictions based on training history (whereas runalyze corrects *VO2 Max* based on race results) which means to me that you can still have a huge gap between the VO2 max values reported by the 2 platforms, while having similar race predictions.

[https://runalyze.com/my/tools/tables]

[https://cicerunner.wordpress.com/2014/07/11/garmin-fr620-race-times-from-vo2-max/]