With watch OS4, Apple Watch now measures also HeartRateVariability in mS ??
But what's a normal value and can someone please explain a little bit more about this HRV, like when and how often it's measured. And most important, like I asked before, what are normal values. My watch now says that my HRV is 46 ms.
Apple Watch Series 2, watchOS 4
Hi I had the exact same question... and was actually a little concerned my readings seemed to appear quite low to what google search results suggested were "normative"
I found a really good website (hrvcourse.com) which has a gender/age chart. iOS records SDNN (std deviation of HRV over short time samples) so if you want to compare your readings from iOS look at the SDNN (ms) column.
FWIW I did speak to apple support about this.. if the trend is provide ever more technical health data they need to put more effort into directing users to "the science" so we can interpret what we're being told.
Hi I had the exact same question... and was actually a little concerned my readings seemed to appear quite low to what google search results suggested were "normative"
I found a really good website (hrvcourse.com) which has a gender/age chart. iOS records SDNN (std deviation of HRV over short time samples) so if you want to compare your readings from iOS look at the SDNN (ms) column.
FWIW I did speak to apple support about this.. if the trend is provide ever more technical health data they need to put more effort into directing users to "the science" so we can interpret what we're being told.
Good evening from the Uk. I’ve been looking in to HRV, basically this is what I have found.
HRV measures your R waves, which you would find on and ECG (Electrocardiogram), such as in hospital.
On and ECG this measure he electrical activity of your heart. But when you think of your heart, this is in 4 sections, 2 Atriums and 2 Ventricals. The blood coming back in to the heart goes in to the right atrium, then pump into the right atrium, then into the lungs, back in to the heart via the left atrium, then pumps in to the left ventricle, then back into the body.
So, on an ecg you can see a wave, labelled ‘P,Q,R,S,T’, (google it, it’s interesting), P is the atrium , QRS is the Ventrical, and T is the re-polarisation.
So basically HRV measures the milliseconds it takes for your ventricles to contract. The lower the number, the quicker they do this, the higher the slower.
So this is what I have looked in to, I do understand that this is a very in depth subject and I may be called out on some things, which will help me to learn more as well. But I hope this helps you all out there in the Apple world.
(Typing too quickly). Blood comes back to the heart to the Right Atrium, then into the Right Ventricle, to the lungs, back in to the left atrium, then left ventricle and back out in to the body through the Arteries
Hi There @Janneman003
I too have been learning about it since it was enabled on the watch. I found this which I hope helps you
In general, a high HRV indicates dominance of the parasympathetic response, the side of the autonomic nervous system that promotes relaxation, digestion, sleep, and recovery. The parasympathetic system is also known as the “feed and breed” or “rest and digest” system.
A low HRV indicates dominance of the sympathetic response, the fight or flight side of the nervous system associated with stress, overtraining, and inflammation.
There is no particular number you need to achieve however you need to get a base line and then observe your results. I hope in the future for more help help interpret these iwatch results.
HRV is relative to each individual. The way it is supposed to be used is to take it at the same time every day, usually when first waking up, and create a baseline over as much as a month. Deviation up or down from this baseline is indicative of your body being rested and ready for activity vs. stressed and in need of recovery.
HRV isn't a set number on a scale . its measurement that should be taken daily , at the same hour , to establish a baseline . it is dependent on variables such as age, gender and recent activity . if you take a reading over the course of a month and the average is 46ms then that is Your baseline . lower than that would imply your in recovery mode higher would imply your body can handle the impact of a hard training session or any other additional stress-or
I found the following (very technical) paper. It seems to indicate less than 50 for the 24 hour HRV is best, but the watch takes periodically not 24hours so this doesn’t necessarily apply the same way.
I had an episode of Cardiac fibrillation Saturday (April 28).
Look at the HVR that day (First image)
On the second image, we can tell that my heart went crazy at 1h10 AM. Note that I woke up only at 2AM.
I went to the hospital and received a second cardioversion in 6 weeks. I never had heart fibrillation before in my life. I'm now on medication.
I bought my Apple watch Wednesday April 25... 3 days before this second fibrillation episode.
Now, that I own this watch and that I'm now aware of HVR... I want to verify if I can use Health HVR data to predict fibrillation.
Thx for the answers. We already know now that a high HRV is a good sign. But I'm still searching for a reference ?? What's a high value ? 50 ? 60 ? maybe 200 ?
I still didn't find anything about that on the internet but I'm still searching for it...maybe Apple has an aswer ?
That's a good tip. The Breathe app does seem to prompt and HRV reading. Still, my research says there are different way to calculate HRV, and in some, lower numbers like 40s and 50s are normal, while in others, numbers in 130s and 140s are normal. I’m certainly hoping Apple is using the former based on the readings I'm getting. 😉
This is the best answer: It’your resting rate, not the daily average.
I think it’s irresponsible that Apple, a company valued at almost $900-billion has a product and doesn’t tell you what it means. It’s like a blood-pressure machine with no instructions.
Apple says the HRV app measures SDNN but there are two different SDNN measurements.
From reading the link below, it looks like the Watch reads SDNN Index. The article says a reading of
https://www.sciencedirect.com/science/article/pii/S0735109797005548
Currently, we have a cardiovascular disease risk factor gap. This means that all the traditional risk factors (blood pressure, blood lipids etc.) associated with cardiovascular morbidity and mortality only account for around 50% of the cardiovascular risk prediction. Heart rate variability a new 'novel' risk factor, we currently do not know how much it contributes on top of this already established 50%, but with the vast amount of data Apple will be collecting it should go some-way in answering this question. Once we know this, validated normative data should be released.
Further reading to type into google scholar:
1)Exercise and cardiovascular risk reduction: Time to update the rationale for exercise?
2) Is cardiac autonomic function associated with cardiorespiratory fitness and physical activity in children and adolescents? A systematic review of cross-sectional studies
Absolutely not!
I just looked at the age graded table that indicated my readings were actually good for my age.
I’m disappointed that apple provide the data without really helping people understand what it means. Even if they say “show your doctor” without knowing more about how and when the data is collected I’m not convinced a health professional would be able to interpret either!
While it’s fine to say over the course of a day you should see a higher HRV value, the watch only measures for short periods of time, during which you are perhaps much more likely to have a steadier heart rate and hence a lower HRV.
I’d like to know more also. Please.
Where do we see this value?
heart rate variability
