SAN DIEGO (CNS) - A two-day health and fitness expo associated with the 18th annual Rock 'n' Roll Marathon is scheduled to begin Friday at the San Diego Convention Center.

Mayor Kevin Faulconer, distance running champion Meb Keflezighi and 92-year-old marathoner Harriett Thompson are scheduled to take part in a kickoff ceremony this morning in the center's Hall B.

The expo is free and open to the public, taking place from 11 a.m. to 7 p.m. today and from 9 a.m. to 5 p.m. Saturday.

Saturday will also include the inaugural Rock 'n' Roll 5K, which begins at 7 a.m. at Sixth Avenue and Palm Street on the west side of Balboa Park.

The marathon will get going in the same area Sunday around 6 a.m. Keflezighi plans to compete on the half-marathon course. Last year, he served as a pace-setter for the 13.1-mile race.

The band O.A.R. will headline a post-race concert Sunday at Petco Park, beginning at 10:30 a.m.