The following is a list of supported apps/devices that can be used to track the mileage for your race:
Fitbit
Garmin
Google Fit
Misfit
Omron
PEAR Sports
Polar
Strava
Striiv
Suunto
TomTom
Underarmour
Withings
Yoo
Samsung Health
Here's how you add your fitness device to the Yes.Fit app: