FusedSpeed benefits you the most when you need highly reactive speed readings during training, for example, when running on uneven terrain or during interval training. If you temporarily lose the GPS signal, for example, Suunto Spartan Ultra is able to continue showing accurate speed readings with the help of the GPS calibrated accelerometer.
To get the most accurate readings with FusedSpeed, only glance shortly at the watch when needed. Holding the watch in front of you without moving it reduces the accuracy.
FusedSpeed is automatically enabled for running and other similar types of activities, such as orienteering, floor ball and football (soccer).