Little could Greek courier Pheidippides have known he was kick-starting an activity that would endure for centuries.

The sport now known as the marathon is said to stem from 490 B.C. when Pheidippides ran from the battlefield of Marathon to Athens to announce the outnumbered Greek army had defeated the invading Persians.

A modern, recreational version of this will unfold Saturday, Nov. 14, when more than 20,000 runners will show off their strides in the 38th Anthem Richmond Marathon.

Last year’s field of 21,657 included a record turnout of 6,549 runners for the full, 26.2-mile marathon. Ben Zywicki of Colorado won the main event in 2:18.35.

Zywicki became the first American to break the tape since Norfolk’s Michael Harrison in 2000. The last Richmond area champ was Tim Covington from Clover Hill High in 1998.

Between Harrison and Zywicki, the winners all have been lithe striders from Kenya and Ethiopia.

Ethiopian Waynishet Abebe was last year’s women’s champion in 2:39.26.

Men’s and women’s marathon winners will be awarded $2,500, with a $2,500 bonus for breaking records.

Record holders are male runner Kennedy Kemei, 2:13:45 in 2011, and female runner Irina Suvorova, 2:31.25 in 2000.

Predicting winners is dicey. Thom Suddeth, the Richmond Marathon’s elite runners director, said the majority of contenders in that category typically don’t enter until the day before the event.

Only a tiny percentage of today’s marathon enthusiasts receive anything more than a commemorative T-shirt, pat on the back and feeling of accomplishment.

The marathon’s races — an 8K and full and half marathons — all begin and end in Downtown. Numerous and frequent road closures will take place along the course, which runs through Downtown, to Lakeside and the Bryan Park area, along Monument Avenue, a part of Grove Avenue and River Road across the Huguenot Bridge, and south of the James River along Riverside Drive, Forest Hill Avenue and Semmes Avenue to the Lee Bridge.

Race organizers hope spectators will line the route to offer encouragement to runners. Musical entertainment will be provided along the course, with several groups slated to perform at the finish line. A post-race party with food and children’s activities will be at Brown’s Island Downtown near the finish line.

In conjunction with the race, the Allianz Global Assistance Health and Fitness Expo will be held at the Arthur Ashe Athletic Center, 3001 N. Boulevard, from 5 to 9 p.m. Thursday, Nov. 12, and 11 a.m. to 9 p.m. Friday, Nov. 13.

For more information on the marathon, including a route map, go to www.richmondmarathon.com or call (804) 285-9495.