I don’t watch soccer, so I was not aware of this:

During this year’s broadcasts of the premier European soccer club championship, TV viewers around the world have encountered a mysterious new number: the total distance, in meters, run by each player while on the field.  When AC Milan’s Gennaro Gattuso was replaced in the 85th minute of the club’s 3-0 defeat of Manchester United in a Champions League semifinal earlier this month, he had run more than 10 kilometers, according to an on-screen graphic. (That’s the equivalent of running the length of an NBA court about 350 times.) This stat is again at center stage today as Milan faces Liverpool in the championship game.

You can find out hey they calculate that number here.