I think its more potential, my 5k/10k are quite accurate but my half and full are quite off - which makes sense as they're the distances I train for. It also doesn't take other factors into account like running on track vs road
That makes sense. If you do longer runs (and long fast runs) then your half/marathon time will be more accurate. In general, the issue with using VO2max to priduct race performance is that it doesn't take into account account running economy which is a massive factor in determining performance for longer distances. Same with lactate threshold, which has a big impact on all distances. E.g. at what point do you go from a metabolic steady state to an unsustainable state. It's the most important factor in distance running in my opinion. The threshold can be at quite a slow pace even for someone with a high VO2max if they are not doing the right training. E.g. think of someone who is excellent at HIIT and has a VO2max of 60+ but can't run a fast 10km.
Pretty sure garmin do take other factors into account for their race predictions as they’ll update when your lactate threshold does, even if your vo2max remains the same.
I think you are right regarding lactate threshold but im not sure how they factor in running economy as it's difficult to calculate. You need an accurate VO2 measurement. I guess they use HR as a proxy but in practise I find HR isn't such a good measure of metabolic output for various reasons; hills, unrelated stressors, heat, aerobic decoupling, etc.
Well.. a crude estimate of relative running economy is pace/heart rate and tracking it over time. Seeing the number go upwards means your economy is increasing and vice versa.
A fair amount of people track this because it's a feature of pretty much every training/coaching app.
