This is kind of related, because I want to do a similar download of what I would call instantaneous heart rate. I have been âexportingâ apple watch heart rate data through the extremely cumbersome process Apple allows (in Health Data, click person icon in upper right, export health data, then either save or email the data through a ZIP file which contains 2 extremely large xml files, and a surprisingly simple CSV file for each ECG recording).
I just downloaded the QS Access App - and am getting frustrated, because I cannot seem to allow it to see or use heart rate data, so I donât know if Iâm missing something simple and obvious. Other apps see âheart rateâ, but QS Access only sees âActive Energyâ
However, with regards to what Douglas wants, what I have learned from my exports and other internet sources is that under normal conditions, the Apple Watch uses the green light and sensor on the back of the watch to monitor pulse rate, kind of similar to the way the red&IR lights do on a pulse oximeter. This does a âspot checkâ of pulse rate roughly every 2-12 minutes. I find no rhyme or reason to how often it does the check.
However, if you start the âworkoutâ app (I start the non-specific âOther - Open Goalâ), the Watch will continuously use the green light to record pulse rate. It is also a little sporadic, giving readings once every 1-10 seconds, but is pretty close to a continuous reading of heart rate in beats per minute. It is possible (pure speculation) that it only reports a new heart rate when it detects a change from the previous rate. But for Douglas, I expect that it would show your tachycardic events nicely.
So now, back to QS Access - I would like to see an App that exports âeveryâ HR event, not an average by any more coarse time scale. I have looked slightly at the Python code listed at http://www.markwk.com/data-analysis-for-apple-health.html which is where I learned about âQS Access.â I donât know if there is any connection between the python code and QS Access. As a Biomedical Engineer, I have dealt with lots of HR data and programmed in many languages, but I feel the Python method is way to complicated for most people, I think they just want a simple way to view their data (HR in this case).
A couple of additional comments about the Apple Watch data:
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when the watch interrupts you to remind you to âbreatheâ it actually records heart data (using the same green light) a little differently - in this case it records the heartâs R-R intervals for that 1 minute period. In reality, RR=60/HR or HR=60/RR, so they are really just different ways of expressing the same information. The difference is that âbreatheâ gives the RR between each beat, whereas the âworkoutâ does some type of very short average. Instantaneous HR is simply 60/RR between each beat.
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finally, the green light pulse method uses only one arm, whereas the ECG recording uses both arms and the ingenious method of picking up the electrical activity of the right-arm vs the left-arm by having the user touch the crown. Douglas, I have the âECGâ icon on my Apple Watch face, and within 3 seconds I can start an ECG recording. Then, using the very cumbersome âExportâ in Health data, I can access the CSV files from each ECG. Excel doesnât automatically do any analysis, but it is simple to open the file and display of graph of the ECG. To get a clean ECG recording, it is important to minimize muscle and movement artifact, most easily done by resting your arms on lap or table, and touching the crown very gently but definitely. I doesnât hurt to lick your finger, which gives better electrical contact compared to a very dry finger. The ECG feature is not available on older Apple Watches.
My sense is that there a void in terms of what Apps are available for heart rate on the Apple Watch. I am interested in what QS Access can do to help me, if I can solve why I cannot access the heart rate data.