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Garmin VO2 Max Calculation

Patrick MarshPatrick Marsh
in Coaching Forum 🧢

My Garmin 920xt does a V02 max estimate.  My estimate of 54 dropped almost 4% over the past month (to 52) as I have ramped up training.  This is the first time my score has been dropping.  My initial estimate was 48 when I bought the device last December.  It steadily climbed with each hard run and reached 54 a few months ago. 

Is this just noise, as the 920xt keeps refining the calculation as more data is collected?

Or is this a signal?  The drop could be an indication of lost fitness, lack of intensity, overtraining, or maybe slower pace as mileage increases.

I am not overly concerned about this as I am satisfied with recent fitness gains.  However, thought I would reach out to see if others had a similar experience.  

 

 

Comments

  • Dino SartiDino Sarti
    I think this is just directionally correct. The only way to really nail it is go to lab and wear a mask connected to a hose and let it really measure your O2 use and capacity. My Feix likes to ship about VO2 Max. I don't put to much stock in it. I think it is more interesting to rely on a stop watch (run) and power meter (bike). Those will give you quantifiable out puts of your fitness gains.
  • Patrick MarshPatrick Marsh

    Thanks Dino.  That makes sense.  

  • Tom GlynnTom Glynn
    There is some science on it over here: https://www.firstbeat.com/app/uploads/2015/10/white_paper_VO2max_11-11-20142.pdf

    I think they do a lot of the software analytics used in sports watches like Garmin. Simply put, they do a regression on heartbeat and speed and use that to estimate VO2. It's pretty interesting, you can see some of the underlying assumptions built into the models. It hasn't swayed me from more of a threshold pace model for training, though.
  • Dino SartiDino Sarti
    I went and did the lab test on a treadmill while wearing the mask and the whole 9 yards. It gave me a number, but I didn't know what to do with it. They gave me VO2 intervals to use to try and lift it. My speed went up, but I am sure if my VO2 Max number moved. I didn't go back to retest. The net was a got faster so who cares about that number... image. The intervals were similar to the EN intervals.
  • Coach PatrickCoach Patrick
    As Tom noted, it's a regression from HR and Speed...so the more "long course" stuff you do, the lower that number you get.

    It's an interesting metric but not something you should track and try to manipulate at this time!

    ~ Coach P
  • Patrick MarshPatrick Marsh

    Thanks Tom.  That is a good article and explains a lot about how the VO2 calculation is done.  Very helpful.  Thanks!

  • Patrick MarshPatrick Marsh

    Got it.  That makes sense.  Glad that the intervals helped with your speed.  Hopefully, I can achieve some speed gains during the off-season.  Appreciate the feedback - thanks!

  • Patrick MarshPatrick Marsh

    Yep - the longer my runs were, the more the VO2 estimate dropped.  This makes sense now.  Much appreciated - thanks!

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