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### Runalyze vs Garmin VO2 max?

Posted: Mon 25. Mar 2019, 17:32
Hello -

Can someone explain further please (I have read the bullet explanation on the Runalyze "?" page) the difference between how Runalyze calculates Effective VO2 max and Garmin calculates VO2 max?

The Runalyze value is much lower, and I'd just like to understand a bit better the calculations for each that result in that, if possible.

Thank you!

### Re: Runalyze vs Garmin VO2 max?

Posted: Mon 25. Mar 2019, 18:10
Never compare the Garmin VO2max with the effective VO2max in RUNALYZE. In 99% of the cases, the VO2max values and prognoses calculated by Garmin are total crap. In contrast to Garmin, we include several factors (such as the correction by already existing competitions - so you have to mark them as such)

### Re: Runalyze vs Garmin VO2 max?

Posted: Fri 29. Mar 2019, 14:43
Here some research based on my experiece in this rather complicated matter:
I found that for me the VO2max value on my FR 935 corresponds very well with my VO2max lab result. However, Garmin’s Race Time Prediction shows values I’m unable to reach.

Digging a little deeper, I found the following whitepaper by Firstbeat: https://assets.firstbeat.com/firstbeat/ ... 6.2017.pdf
For the Race Time Prediction, the Firstbeat algorithm in Garmin's watches just uses Jack Daniels' Race Time Prediction Table (Table 4 on page 7), which Firstbeat calls "Race time prediction based on VO2max".

There lies the misunderstanding: Jack Daniels does not use VO2max. He uses his own concept called VDOT, which is not the same! The scales are different. *)

Runalyze correctly labels their own concept “effective VO2max”, because it is "reduced" by some factors regarding your running efficiency.
Therefore, Runalyzes “effective VO2max” is much more similar to VDOT than to VO2max. I found that their prognosis also matches my race results very well.
Garmin determins VO2max more or less successfully, but this value alone is useless and inserted into unsuitable (VDOT-)tables produces wrong results.

*) Comparison between VO2max and VDOT:
Take the Cooper test:
- If you run 3 km in 12 minutes, you will get a VO2max of 55.8.
- If you run 3.219 km (2 miles), you will get a VO2max of 60.7.
(Formula: (Distance covered in meters - 504.9) ÷ 44.73)

Using Jack Daniels' tables (https://www.coacheseducation.com/endur/ ... nov-00.php ) for the examples above:
- For 3 km in 12 minutes, you'll get a VDOT of 47.9.
- For 2 miles in 12 minutes, you'll get a VDOT of 52.1.

This shows that VO2max and VDOT values are not interchangeable! For both distances, VDOT values are only about 85 % of the VO2max values. So if you have a VO2max of 56 and a VDOT of 48, the Garmin/Firstbeat algorithm will look into the VDOT table with 56 instead of 48 and therefore get a much too optimistic race prediciton.