"With the W580 Walkman® phone you can even take your favourite tracks to the track. It will count your steps, your calories and monitor your running speed/distance/time. Add to that your best tunes for motivation and whether you’re on a run, in the gym or just out for a stroll, the W580 is the perfect fitness partner."
Above is SE's description of the fitness app that comes with the Z580. This video from slashgear shows the app in action. Enjoy.