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Comment by mvkel | Hacker News Reader

You should know that vo2 measurements that aren't performed via gas exchange or blood measurement are a complete guess.

The other thing is the denominator of vo2 is weight. So losing weight without working out at all will increase vo2

It really doesn’t matter for most amateurs trying to improve their health whether the metric is accurate or not. The huge benefit of fitness trackers is that a metric is a metric is a metric. Eat less, exercise more, sleep soundly - you can’t go wrong, and if the metric is steps, or HR, or pace, or calories burned, or (in this case) estimated VO2max and seeing improvements in those metrics relative to a baseline is a motivating factor then that’s all that matters.

Well done to OP. Keep it up.

The problem with the VO2max metric is that there is no measurement of it outside of a few lab methods, certainly not in a fitness tracker, so they're estimating. It makes more sense to look at the other metrics that it CAN easily measure, like heart rate recovery to get a quantifiable and repeatable measurement. I agree for amateurs accuracy is not necessary, but repeatability is. If I weigh myself today and the scale says 10 lbs below my actual weight, and tomorrow it's 10lbs above my actual weight that's a problem. If it's always 10lbs below that's fine, the delta will be correct. You can't say that for VO2max you get out of a fitness tracker.

My watch says my VO2max is 36.8 which would put me very strongly in the long term negative health effects bucket and well below average. Meanwhile Garmin claims it's 51 which would put me in the top 15% of my age group. It can't be both. They're just made up estimations, and following them blindly could be dangerous. What if someone's is going up even though they're not actually doing a healthy amount of exercise? Or someone's is going down or maintaining even though they are, causing them to fall into negative thought or behavioral patterns? Better to stick with some other data points

I myself did a lot of exercising during the last 1 1/2 years using an apple watch for measures and I would also go with the previous comment:

Even thought the VO2max is not accurate (especially not compared to actually lab data) it is a nice graph with a tendency which REALLY helps.

High differences might come from different estimation techniques and thus this value is not comparable among different brands but it seems to be for your own value and progress.

During a lazier time it depleted a bit, now its going up again.

Most other graphs don't show it that nice. E.g. your avg hearth rate will not make huge changes (and drop which, even if its good, doesn't feel that good).

Edit: I actually did a Lab test (not VO2max) but an exercise ecg with lactate measurements. I couldn't choose between running and cycling. The problem is: if you choose the bike they can measure the values while you continue riding. If you choose running you have to stop now and then while they take a blood sample. Even there it isn't 100% accurate and might yield different results based on the used method.

I think you just want to track both over the long term - that is compare your watch with your watch and your garmin with your garmin.

But that is a huge gap, I think in general running creates more realistic VO2max data than cycling since there are too many factors at play (e.g. if you're in a group or not or using the drop vs. not).

I disagree.

Weight loss doesn't automatically mean "healthier."

Using vo2 as a metric of "health" would not be correct if weight loss is the sole attribution of vo2 gain.

One can lose weight without doing a minute of exercise and vo2 would increase.

If one is interested in getting healthier, I think it's well worth the time to learn about how the metrics work.

My point is that for most adults in the world right now (western, industrialized, developing, modern, whatever) there is an obesity epidemic and any amount of focused self-care through exercise and diet will improve health outcomes. Eat less, exercise more. If an arbitrary metric on fitness tracker helps you reach that goal, then just do it.

Yes. But at least the watch is comparing against a previous measurement, making the baseline consistent.

It could have been named Vo5max and for me it'd have worked. In the real world, this number actually tracks pretty linearly with how much faster I'm able to climb a hill on a bike.

> In the real world, this number actually tracks pretty linearly with how much faster I'm able to climb a hill on a bike.

That's because both of those things are directly related to weight.

(VO2 max is usually given in a weight-normalized unit. So losing weight will make it go up as long as you at least maintain your fitness).

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