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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

    VO2max is calculated as a rolling average, thus only one or a few runs don't affect its estimation drastically.

  • 0 over 2 years ago in reply to 7dfcd1938c0146f1804397d33ddc9c14

    Yes, I understand that, but in the last few months I have been clearly improving fitness, doing more interval work and these runs are just the illustrating that longer progress. VO2 being stuck solid for months during that progress just feels wrong. 

  • 0 over 2 years ago

    Mine is quite correct, maybe a little optimistic

  • 0 over 2 years ago

    On my forerunner 935 vo2max and race prediction is total rubish.

    From my experience the algorithm has a great bias towards intervals. If I do a lot of high intensity interval trainings, I can get my vo2max up to 63 which predicts a 5k time of 16:33 and marathon in 2:38.

    If I do a lot of endurance runs, the vo2max drops to more normal values, around 53.

    I’m 52, I can do a coopertest in 3040m. So a vo2max of around 51-53 is about right, with a pr on 5k of 20:24 and marathon in 3:28.

    Don’t pay too much attention to garmins algorithms. Garmin marketing tries to make them sound scientifically, but they are quite simplistic.

  • 0 over 2 years ago

    Race prediction is rubbish on 955. I did 3:12 marathon with HR avg 161 wearing a hrm strap and race prediction was still 3:22/3. 

    5km prediction is a minute slower than what I did in a training run 2 weeks ago. Never mind in a race. It was close enough till around October or November and then an update came out and all race predictions just dropped straight away

  • 0 over 2 years ago in reply to gmaccauley

    It's getting worse for me! 5k prediction this morning... 22:04. I've just run a trail parkrun in 20:10! That's not even a margin or error! VO2 has flatlined since I got the watch and despite a 100k week and clear progression on times and fitness, I'm constantly just 'maintaining'. HR zones setup and good. It's a bit of a waste of £400 when the 'advanced metrics' are useless. 

  • 0 over 2 years ago in reply to gingerneil

    Mine has be fairly realistic in fact it showed 18:44 on Friday for 5k and I did one yesterday at 18:46 (rather unexpectedly to be honest) .  My Garmin VO2 max and the Runalyze version are also fairly close, within 5%  I suppose its a combination of various factors impact that one of us sees accuracy and others not. In general the metrics seem to mirror closely how I feel, even HRV which took a dip seemed to correctly pick up when I wasn't feeling at my best , and has subsequently recovered.

  • 0 over 2 years ago in reply to S.M.R.

    It probably has more to do with how you train. If you train in the same way garmin’s algorithms are designed you might get perfect results. If you train any other way the results might be totally wrong. 

    None of the garmin users in my athletics group have accurate race predictions. 

    As I said before, in my experience garmins algorithms are fairly simplistic and are great for people who just want to collect data or over quantify their lives. For experience amateur athletes who know their body and one or two things about training the numbers aren’t that usefull. Some trends are nice to see, but expecting the numbers to be accurate isn’t realistic.
    But I understand people expect them to be correct, considering the amount of money they paid.

  • 0 over 2 years ago in reply to Elbo

    For once I am in line with something RoflRoflRoflRofl

  • 0 over 2 years ago

    My current predictions:

    • 5k v02max widget prediction - 22:50 (very accurate, my pb last year was 23:10)
    • 10k v02max widget prediction - 48:27 (very accurate as well, I did run sub 50 last year)
    • Half Marathon v02max widget prediction - 1:48:30 (a bit optimistic, I did run sub 2 in november)
    • Marathon v02max widget prediction - 3:56:16 (fairly optimistic, I did run sub 4h30 last month)
    • 90km (Comrades Marathon) race widget prediction - 7:00:33 (???)
     
    My watch thinks I can run a 90k quicker than 2 consecutive 42k's?