The runner who smacked a TV reporter on the butt during a race in Georgia last year just plead guilty to sexual battery ... and he'll now be on probation for the next year, TMZ Sports has learned.
Thomas Callaway was facing up to 1 year behind bars after he was arrested last December for slapping WSAV-TV's Alex Bozarjian while she was reporting live from the Enmarket Savannah Bridge Run.
Video of the incident was alarming ... Bozarjian was speaking to the camera when Callaway ran up from behind and hit her hard.