Detector specific person

I would like to create a computer system that electronically detects the passage me to finish or arrival of one or more athletes in a foot race. For example, if I pass I must say "fabio22 is past," if it passes another I must say "dude is past." I know help?. Thanks in advance.

Sorry for my bad englsh, but I am italian.
This is my post in italian forum :

RFID is what you're looking for. But distance between sensing device and place where people will be is important - how close this device could be?