We have finally finished our first development iteration of CardioMood framework and published an update for our apps.
This new update incorporates the following changes:
We changed synchronisation process so that you can be aware of its progress
Minimum measurement duration was lowered to 50 RR-intervals
In Expert version, we fixed the rolling window size to 50 RR-intervals for most of parameters
To keep you informed about the updates, we added “News” tab.
We disabled exporting raw data in HRV Lite. Oups! :)
The update also fixes a couple of bugs. If you want to know specific details, please continue reading.
We thought that it’s important to keep you informed of what’s going on in our project. Since version 2.1 our android apps have the “News” tab.
This is basically an embedded web-browser which shows this blog. All internal links will open within this browser, while links leading to external resources will be handled by the Android system. You can go back by clicking “Back” button of your phone. To refresh the page, you can use a button on the menu.
Right now you cannot disable this tab, but we promise to add a configuration parameter.
50 RR-intervals as a minimal duration
There are plenty of apps that calculate your HRV. Even though they use the same parameter as HRV = 20lnRMSSD, the duration of the recording varies from app to app.
Elite HRV takes 2.5 min recording. Famous ithlete has a 55 seconds duration limit. Setting a limit by time may result in significant difference in RR-intervals count – different measurement will contain different numbers of intervals. As all time-domain metrics (including our favourite HRV) are basically statistical parameters, they are comparable only when the sample size is the same, i.e. the measurements have equal number of RR-intervals.
The duration limit should be chosen based on the purpose of the measurement. For checking your stress level we recommend 2-min duration limit. To estimate HRV it makes more sense to set interval-count limit (100 or maybe 50 RR-intervals).
Changes is parameter calculation
HRV parameter shown in “History” tab was updated. Now it is calculated as an average of 20lnRMSSD for a rolling window, with size being 50 RR-intervals and step 5 RR-intervals. For a trained individual with resting heart rate around 40 – 60, the window will be about 1 minute. We are still experimenting with the parameters, but for now we think 50 RR-intervals will be enough for HRV.
In HRV Expert, we’ve also changed some graphs:
pNN50, 20 ln RMSSD (HRV) graphs were added.
They use the same window size – 50 NN intervals.
Time-domain, frequency-domain and histogram parameters are still calculated using all data.
Two parameters use individual window sizes:
Stress index is calculated using 2-min rolling window (the average is shown under “Histogram” tab)
Gorgo “A” Index is calculated using 100-interval rolling window (the average is shown under “Histogram” tab)
Emphasizing again: all basic parameters in the report (except Stress Index and Gorgo Index) are calculated over all recorded data.
Unfortunately, synchronisation is still not cancellable and blocks the UI… The good news is that now it shows its current progress. This is another step towards a silent background synchronization. We will eventually do this. Promise. :)
There is one more interesting thing to mention. If you have multiple devices or use both HRV Lite and HRV Expert apps, now when performing synchronisation, the app will only download the list of new measurements skipping the data. The data for each new measurement will be downloaded from the server when you first time open it (“lazy” download).
If you have many measurements and reinstalled the app or logged in from a different device, the synchronisation will take several seconds. If you want to see the report, the app will automatically check the presence of data and download it (the Internet will be required) if necessary.
If you have more questions or suggestions, please contact us via [email protected] or just use a Feedback form in the app. And don’t forget to rate our app in Google Play!