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I’ve had serious doubts about my Apple Watch and its data. It’s so much different than the Fitbit I used to use. Fitbit told me I was sleeping deeper, had better HRV, and was in better cardio shape. Apple tells me I suck across the board. So I’ve stopped measuring. I find it hard to believe that I can run for a full hour three times a week and be considered below average for cardiovascular fitness. But that’s the determination of my Apple Watch.

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Great article as always, Marco! One thing we wish to see if you could do an article of what the numerical number really means in terms of fitness or lack of it. We have some master athletes in their 60's and they normally report consistent HRV in the 45-50 range (rMSSD), but with very low HR for their ages (39-45 bpm). But we have read people talking about 100 and higher HRV ranges... Enlighten us please!

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thanks Ruddy! Resting heart rate in this context is a much better marker of fitness, with respect to HRV, this is why for example good master athletes tend to have the same resting heart rates they had when younger, while HRV tends to decrease with ageing. See also here: https://marcoaltini.substack.com/p/cardiorespiratory-fitness-vo2-max

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Is there any thought to us looking for too much correlation to good things with HRV? I feel like we are trying to make it the be-all end-all metric.

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great point. I think that's the issue also behind giving a lot of weight to absolute values, which I think is an highly overrated way to look at the data (see here for more considerations: https://marcoaltini.substack.com/p/absolute-values-of-heart-rate-variability and similarly here: https://marcoaltini.substack.com/p/low-heart-rate-variability-hrv). Let alone that the current madness with wearables brought us continuous HRV turned into stress scores (with no access to the raw data, because it would be complete garbage), something that if taken seriously, would bring you to anorexia (the best way to increase your HRV is to stop eating - how is that for our health?). Similarly, things that are good for us, like exercise, are always negative from an acute point of view (during or after a stressor, even for hours), leading to the most incorrect interpretations (see also: https://marcoaltini.substack.com/p/a-quick-note-on-continuous-heart). In my view, less is more when it comes to HRV, and a good protocol, far from stressors, can help us capture how we are doing, without the issues associated to looking at the data too tightly coupled to "anything we do". Either way, even when doing things properly (i.e. with a morning measurement), we still need to keep in mind that HRV is just a tool which can allow us to make small adjustments to our plans and behavior, but we should always look at what matters the most, i.e. our health (or performance) and not the HRV data itself. I hope this provides some useful pointers

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One thing you need to consider about magnetic clothing or whatever when you're sleeping. My partner just received one that new high pacemaker. no electronics, possibly magnetic should be close to the pacemakers because they communicate with the devices that communicate with each other . The manufacturer is. Aveir Leadless Pacemarker. I have been using your product and polar watches for many years

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