Many of Polar's fitness watches, to include the Vantage M model, have the capability to estimate V02 using heartrate variability as a proxy. There are at least a few peer reviewed papers that have concluded that these estimates are sufficiently precise to be used to track trends in a user's fitness over time even if they are not completely accurate. Indeed, in my own experience the estimates appear internally consistent in that the values produced don't vary much over the short term, but do vary in an explainable way over long periods of time during which my fitness regime has changed. That observation is based on years of data.

However, I recently have observed that my estimated V02Max has dropped dramatically. It had for several years been reporting a values in the mid to high 60s. It now reports values in the high 30s. There's a startling inflection when graphed over time. My exercise regime was consistent over the period when I observed this change.

I concede that values in the mid to high 60s are probably an overestimate, so either the heart rate sampling or the proprietary algorithm used to deduce V02 Max (or both) probably have something wrong. Even, so I'm inclined to believe that something has dramatically changed and I'm not sure how to account for this. Are there any conclusions to be drawn? Where should I look for explanations?

  • When your exercise regime was "consistent", does that mean you did the same things or that there had been consistent progression? I ask because it may well be that you pushed your limits (adaptation to cardiovascular training) and the fitness watch lacks maximum stress data now because the load increased less than the possible output. May 16 at 9:01
  • @PhilipKlöcking Good question. What I meant is that I had done comparable workouts for the duration in question. May 16 at 16:39
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    Comparable workouts can mean a lot. If they are comparable in volume/weight for strength and comparable in pace and length for endurance, the effect mentioned could play a role. Your system gets used to the stress, there is a lower heart rate with lower variability. If it means comparable in intensity, meaning you always go all out, it could still involve some kind of adaptation on the cardiovascular and neuromuscular level. Basically, if your training lacks variability in the amount and kind of stress it exposes yourself to, it isn't really training anymore at some point. May 16 at 17:07
  • @PhilipKlöcking Intuitively it makes sense to me that if you're training becomes too routine it's not really training anymore. But surely your fitness should remain more or less static over that period, no? The implication must not be that you have to do progressively harder workouts to keep your V02Max where it is, right? May 18 at 16:44

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From the comments, I do think that your problem is that your fitness status is stagnating.

That is because your training input and stress levels basically remained the same. If that happens, your body does adapt to these inputs.

Therefore, your body does not even reach its maximum power levels. These levels adapted to your training. Thus, if your training does not become harder, you train at levels your body adapted and got used to. Where, I ask you, should your device get the data to derive your max VO2 from, then?

VO2Max is a measurement taken for the maximum power output level your body can possibly have. If you do not push your body to these levels because you stopped to make your training routine progressively harder, the device lacks the data for your maximum output level to derive the measure from. Therefore, it would not be surprising that the measure it takes out of the data it has is faulty.

  • I am convinced :) Thank you for your thoughtfulness and consideration! May 19 at 14:36

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