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Is race predictor utterly broken?

gingerneil
over 2 years ago

Been using my 955 since release and generally happy with it, although it has rebooted a few times recently when pausing and using garmin pay mid run..

However, my main issue is with race predictor and VO2 measures. 

I've been injured for a while, and then focusing on base build for ultra marathons. VO2 seemingly fixed on 51, and capable of a 5k in about 23mins flat out. 

Since October I have upped the miles, and upped the intensity. 5k time has come down to 20:26 this weekend (about 85% effort after 18 miles the day before and a 60 mile week), and today I ran 2x5k with 60s standing recovery between them, and clocked 21:50 and then 21:35.

VO2 on the watch has stuck at 51 since November, and race predictor says I should do a 5k in 21:44.. 2 days after in ran one, with high acute training load, over a minute quicker! 

I use a scosche rhythm optical heart rate monitor for every run, and got far better data out of my 945 than I am getting now (same hr monitor). The 945 gave a VO2 of 54-55 when I was running similar times last year. 

Lactate threshold hasn't shown data in Garmin connect since September! 

Firmware 14.13

What's up with this, and is it a known issue that's being looked at? Or am I missing something? Is the VO2 somehow stuck? 

  • 0 over 2 years ago

    It's just a formula, so what? People here seem to complain about almost everything, even little things like this race prediction formula.

  • 0 over 2 years ago in reply to Brisk Walker

    I don't think people are complaining, just providing some commentary about a feature - I think we should be allowed to do that.   For some it seems ok, for others it doesn't quite line up.  We're just passing on our experiences, maybe that will help someone.

  • 0 over 2 years ago in reply to Brisk Walker

    True, even though it would be nice if it lines up with reality even a bit...

    Which it does perfectly fine for me btw, but can be way off for others.

    Think one of the larger complaints I read were people complaining about the fact it was predicting times which were (way) slower then a time they actually ran. (While to be honest, if you run a 3hr marathon and it predicts you can also run a 3:30 one it isn't wrong ;) ).

    Just noticed the same was the case with stryd (predicting a time slower then the actual time your ran) so just wanted to show it's not JUST Garmin having this strange behavior.

    Anyway, I use all metrics as guidelines... They often confirm what I feel or think and but in the end reality is leading. It IS nice to have some history to look into and see trends though in actual numbers.,

  • 0 over 2 years ago in reply to FlipStone

    It is also terrible for ultra marathon distances. Kind of weird for "Forerunner" watches with 12+ hours GPS battery life.

  • 0 over 2 years ago in reply to Aslam

    To be fair, circumstances are impossible to predict anyway (temps, ascent/descent, etc) for those...

    At most a '80k ultra on flat asphalt at 10 degrees with hardly any wind" might be an option. But anyway, the longer the distances the harder to predict I guess.

  • 0 over 2 years ago in reply to FlipStone

    Agree that the longer the race, the harder to predict. But for me, the issue is not the prediction, is it the fact that if the prediction is so far off, then the other metrics such as LTHR, VO2max etc are also likely to be way off - after all, isnt that what is used to determine the prediction? For example, my 5k prediction is 21:40 - I ran 19:48 last week. If that is so far out, how wrong are all the other metrics that the watch uses to determine condition, recovery, suggested sessions etc etc? We pay all this money for those advanced features, but if the metrics used to define them are wrong, the watch may as well be a random number generator.

  • 0 over 2 years ago in reply to gingerneil

    Mine have been fairly close , as an example I created an event with a course and elevation for a 5k and it estimated 19:10 and I did 18:45 ish. It shows a flat 5k (race predictor) at 18:15. My half marathon is currently showing about 30s off a time aran about 6 months ago so seems fairly close,

  • 0 over 2 years ago in reply to gingerneil

    My opinion is that you don't need to be concerned about those other metrics, unless you have specific  reasons to suspect your values, eg. your HR not tying in with your pace, or your recovery taking longer, etc. 

    The 955 is new to me, and has pretty much got my threshold and max HR spot on after just a few weeks. Just my experience of course.

    I view predicted times as quite a different thing, indicative only and you certainly wouldn't base your training on those values.  

  • 0 over 2 years ago

    Does anyone know how the race predictor works for races that have been added to the calendar for several months from now?

    I’m returning from injury and as I’ve ramped up my weekly volume my predicted marathon time has dropped from 3h55m to 3h33m over the last 5 weeks. I have a marathon scheduled in Connect in 23 weeks. For that race it predicts a finish time of 3h34m. 

    So after 5 weeks of steady improvement it thinks I’m going to plateau for the next 23 weeks?

    What is Race Predictor looking at for these future races?