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how is vo2 max calculated ?

jpgob
over 4 years ago

I know that vo2 max estimate is highly dependent on average heart rate and average pace, but sometimes it just doesn't seem right. I run the same 10 km jogging several times a week, since about 3 months; during this period the vo2 max gradually went from 54 to 58. But it seems to be just a trend, a moving average taking into account the last N previous runs, rather that a measure for the run of the day. Exemple : a few days ago i was very fit  and got 58 for a pace of 4'10" / km and average HR of 151 bpm; but since then i'm not so fit and today i did 4'20" / km with HR of 153 bpm : still 58 ...   I use a ConnectIQ application that computes a running index (the same one that on Polar watches), this running index is a better indicator for fitness : 67.3 when i was fit, 63.7 today.

  • 0 over 4 years ago

    The formulas are very simplistic, involving your HR after a mile of jogging factoring in your sex, age, and weight. One problem I've found is that if you train at a slower pace but for longer times, this will lower your VO2max estimate. I'm guessing your VO2max isn't actually going down, but the formula is waiting for you to do a sprint mile, for example, and if you don't do it regularly, it makes it look like you are lagging.

    Wikipedia lists a whole bunch of different methods, if you want to compare. (The gold standard is to go to a clinic and have a direct measurement made. You wear a mask and run on a treadmill.)

    https://en.wikipedia.org/wiki/VO2_max

  • 0 over 4 years ago in reply to JthanTris

    If you keep increasing your average heart rate during an activity then your VO2 Max should also increase?

  • 0 over 4 years ago in reply to Gadams99

    No, it will go down if the heartrate is higher by the same pace.

  • 0 over 4 years ago

    I think it should go without saying that this metric is not accurate. The only way to measure it accurately is to go to a clinic and have it measured directly. They put you on a treadmill and you wear a mask. It determines the change in amount of oxygen in your inhale vs. exhale and the volume you inhale over time, giving a very accurate uptake of oxygen vs. time. Dividing by your body weight gives the final metric in ml/kg/minute.

    I say all of this to point out that a watch can't possibly do this measurement and must do some crude approximation, so don't over-interpret the result!

  • 0 over 4 years ago

    thanks for the answers but i found enough informations in this post https://forums.garmin.com/sports-fitness/healthandwellness/f/vivoactive-3-3-music/140117/how-vo2-max-is-calculated ; the firstbeat algorithms (https://assets.firstbeat.com/firstbeat/uploads/2017/06/white_paper_VO2max_30.6.2017.pdf) take only into account 'reliable data' , it could explain why even a on a bad run the vo2 max is still good because it measures only a fraction of the run, or because any other subtlety ... Anyway my conclusion is that it's certainly not an accurate measure of the real fitness level of the day, perhaps is it good for long term evolution; as i said the Polar running index is more in accordance with my personal feeling, and after all, all those metrics can be fun (and a rationale excuse for buying those expensive watches ...), but  i don't need it to know if i did a good run or not (running fast and feeling strong, or on the contrary nearly out of breath during all the run) and in the end the last judge is the chronometer, if i can easily run my 10 km one minute faster that i did a month ago, for sure i'm a better runner.