There are lots of free tools available for smartphones to help participants measure distance. We recommend using RunKeeper as it is integrated with our results platform. Other tracking options include: Strava, Zwift, and Nike+. You can also use a GPS-equipped smartwatch, like a Garmin (or some versions of the Apple Watch) to record running distance. Or, kick it old school, and drive a route using your car’s odometer to measure it before you complete 10K!