I was under the impression you have to be wearing a HRM and outside for the F5 to calculate your perf cond when running (and with a power meter when cycling), however I just finished a 4 mile run and dropped a few points thanks to some flakey elevate HRM numbers :-/
There just needs to be HR data of some sort, either a strap or the built-in sensor, for performance condition and Vo2Max. The only stat that requires a strap is LTHR since that calculation needs HRC/R-R data that optical HRM can't give reliably.
