I finally replaced my old phone last week and opted to go with the S9+ because it has the built in Heart Rate Monitor (HRM). This was useful for being able to measure Heart Rate Variability (HRV) without needing an external, specialized HRM to do so.
I was also intrigued by the HRMs purported ability to measure blood pressure, which is a new feature. In the past you needed a blood pressure cuff to measure blood pressure.
Here is what I have learned so far:
There is only one app (as of this writing) that can use the blood pressure technology for the built in HRM. That app is the My BP Lab app. You can find it here. This is a wellness focused app (akin to Welltory), so it does other things in addition to measuring blood pressure. The app used blood pressure along with other health/stress informaiton you provide to make lifestyle and wellness recommendations. I don't have any recommendations yet, so I don't know how well it works. You can use the app without the S9 HRM, but you need some other way to measure your blood pressure.
The sensor currently requires you to input an initial blood pressure reading from an external source at the same time that you take your baseline reading using the HRM in the device. Without the additional baseline reading it can only measure differences in blood pressure as a % change from the baseline.
The ramificaiton of number 2 is that it isn't really capable of measuring blood pressure, it's measuring something and then it can measure differences from that. Those readings and changes can be interpreted into a blood pressure reading as long as you have an initial reading to go along with the baseline. It's still neat in my opinion, just something to be aware of.
It may that this changes over time and as they collect more data (from Quatified Self nerds, such as myself) they'll be able to do blood pressure directly. I'm interested to find out.
I've been using the app for about a week and I had to do one recallibration using my Qardio blood pressure cuff.
The early morning reading I got from the app seemed off to me. I double checked with another device and it was off. So I re-baselined in the app. The app allows you to do this, which seems like a good feature and also possibly a bit telling.
I don't know how it handles previous measurements if you do a rebaseline. It certainly seems to call their validity into question. I'm pretty sure that, at least for the app's purposes, it is going to assume their correct and keep them around. I don't have any reason to feel that other, earlier, readings were off. They seemed in line with what I got with Qardio throughout the day, though I wasn't comparing them side by side every time.
Yes, I own a Bluetooth blood pressure cuff. Why wouldn't I?
As I have been pursuing my journey related to mindfulness and stress-reduction, I've been applying things to my life and seeing what helps and what doesn't.
If I divvy up 20 - 30 minutes of meditation time and use 3 different biometric devices, am I getting the same value as if I just sat there for 30 minutes and meditated?
I'm probably not.
I think that a lot of meditation and mindfulness practitioners and experts would probably take exception to what I'm doing.
At the same time, it's fun for me to do it this way, I get to play amateur scientist and try out technology I'm interested in.
I also get to look at different signals from the body and understand a bit better how they work.
This is fun for me.
Also, I get to write blog posts about them and that is also fun.
On the subject of playing amateur scientist and HRV and mindfulness, I've started using Welltory.
When it comes to HRV, Welltory does a great job of providing interpreted results and education. They provide a lot of information and integrate with a lot of other products that I use (FitBit, Google Fit, Qardio).
Welltory very much encourages the 'try it and see' or 'amateur scientist' approach to quantified self, which aligns well with how I do things. They encourage you try things and see if they help.
All of this puts me squarely in the realm of 'Quantified-Self Nerd'. Which is OK with me, I think. I'm turning the stress and stress management into a fun and interesting activity, which helps reduce stress.