https://www.theguardian.com/technology/2014/jan/20/spotify-sensors-heart-rate-mood-playlists-motion-tracking https://www.theguardian.com/technology/2014/jan/20/

https://www.theguardian.com/technology/2014/jan/20/spotify-sensors-heart-rate-mood-playlists-motion-tracking https://www.theguardian.com/technology/2014/jan/20/spotify-s... mmm and there seem to be a couple (mostly dead) apps that did it, too. This would be useful though, as I listen to high BPM when running, then run to the beat, but if my heartrate starts approaching some max then it would be nice for it to pick songs that have a progressively lower bpm to get me to adjust my stride while running.