Storing of R-R heart rate data inside the fitfile.
This data can be used to calculate Vo2 max and other similar properties afterwards using 3-rd party software such as https://runalyze.com/dashboard Someone stated in the beta thread that from 2.96 the R-R data is only stored if you use an external HRM, not the optical. (Optical R-R looks like crap anyway so no problem really)
