I have just received a 935 after wearing an old 405 for years. So far I don't believe that I'm having any major issues with it and I kind of like the information, but I am believing that I have to take it all with a grain of salt considering the "race predictor" numbers. At my age, if I ran the marathon time it predicts - I'd be setting world records (well not quite, but I'd re running Olympic Qualifying times for a 55-59 yr old woman). How are these race predictors calculated and can I believe any of it to a degree? I'd say the marathon predictor (in my case) is about 45 min faster than I could run now, and the rest of them are closer to my PRs (set in my early 30s) than reality (but also close to Age Graded times). Anyone have any thoughts on this?
the race predictor is a bit on the positive side indeed, if you subtract a point or 2 from your vo2max and calculate predictions on that it'd be closer to reality. if you don't want to do recalculation trouble you can also just add a minute (or 2) to your 10k prediction time :)
I know my 5K predictions were working towards trying actually to kill me should I try to hit each marker they provide. I remember late spring/early summer last year I hit the prediction the watch supplied to me, but just so, which pushed my Vo2 max a point higher in the process. It cut my 5K time by nearly three minutes afterward.
Suffice to say I didn't get close to that prediction the whole summer, and my VO2 didn't move in any direction for a good two months afterward, which when it did move, it moved up (one point), race predictor did not. After that, I just stopped paying attention to the prediction and focused on Power/Cadence/Vertical Oscillation. If I had tried doing what it was telling me, I might have hurt myself doing it.
I don't run for races or contests, so at most the prediction just became a thing to play for myself.
The 935 always seems to give too high VO2Max. The race predictions have been the same since the FR620. It’s definitely an area Garmin could improve in the next gen.
The VO2max value on the watches isn't too high (at least for me it corresponds very well with my lab result).
The problem is the race time prediction table used by Garmin/Firstbeat. If you read their whitepaper ( https://assets.firstbeat.com/firstbe..._30.6.2017.pdf ), they quote an example of Jack Daniels' Race Time Prediction Table (Table 4 on page 7), which they call "Race time prediction based on VO2max".
There is the misunderstanding. Jack Daniels does not use VO2max. He uses his own concept called VDOT, which is not the same or interchangeable with VO2max. The scales are different. Here is the complete table from Jack Daniels, correctly marked as "VDOT": https://www.coacheseducation.com/end...els-nov-00.php
Just a quick comparison: 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. Using Jack Daniels' tables, you get a VDOT of 47.9 for 3 km in 12 minutes and a VDOT of 52.1 for 2 miles in 12 minutes.
Conclusion: For the distance of 3 km and 2 miles in the running time of 12 minutes, VDOT values are 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.
Somehow Garmin and Firstbeat think that the concept "VDOT" is the same as "VO2max", which it is not. Therefore, their race prediction does not work.
It's been discussed so many times on these boards, just ignore the predictions, they're way off, in parts because they mistake VO2Max for VDOT, like th3oretiker_ explained again.
@th3oretiker_: exactly. Calculating VO2max and using VDOT-tables is producing wrong results as these are not the same.
Btw what made my predictions a lot better is lowering the maximum HR to a value that has been reached in the last months and not the maximum theoretically possible number which is a bit higher of course.
Btw what made my predictions a lot better is lowering the maximum HR to a value that has been reached in the last months and not the maximum theoretically possible number which is a bit higher of course.
Uhm, that's generally how you go about your HRMax anyway. You take your most recent reading like from intervals, hills, or a 5k, not a maximum you reached some day years back.
No, max HR value is more or less stable and only slightly degrading with age. Not directly depending on training status. A physical attribute, no training indicator.
