I was reminded by a tweet from @Fellrnr to mention some very interesting work Marco Altini has been doing with the Scosche Rhythm 24.
Source: hrv4training.com, published May 2018
Marco is the author of the app HRV4TRAINING which uses your smartphone camera to take HRV readings. Apparently that is a LOT more accurate than you would imagine.
He has also looked at the Scosche R24 compared to a Polar for measuring HRV by looking at the beat-to-beat intervals (R-R) and then doing some clever maths. The clever maths is fairly standard for HRV and is rMSSD…root mean square of successive differences. Now you know.
Putting known problems with the hardware aside, it seems that, quote, “Results are very good considering normal variation in physiology and limitations in data synchronization.” Marco also cautions the user against moving too much, which may affect the data quality.
Take Out: You might get good HRV readings from your Scosche R24 at rest.
Here’s a graph from the article. Click the graph to read the article.