Using UltraTrac Mode
Before using UltraTrac mode, you should run outdoors a few times using normal GPS mode to calibrate the device.
You can use UltraTrac mode for extended activities. UltraTrac mode is a GPS setting that periodically turns off GPS to save battery power. When GPS is off, the device uses the accelerometer to calculate speed and distance. Speed, distance, and track data accuracy are reduced in UltraTrac mode. The accuracy of the data improves after a few outdoor runs using GPS.