The Washington area's largest participatory sports event of the year begins Sunday at 9 a.m. when more than 9,000 runners set out from the Iwo Jima Memorial in Arlington on a 26-mile 385-yard jaunt through the parks and streets of Washington and Northern Virginia in the sixth Marine Corps Marathon.

First run in 1976, when it drew only 1,600, the Marine Corps Marathon has become the second-largest marathon in America, eclipsed only by the New York Marathon, which drew almost 15,000 runners Sunday. Unlike most other marathons, the Marine event is not aimed primarily at world-class runners.

"They make the average runner feel that this is his race and really, it is," said Bill Squires, a Boston-based running coach who has worked with such world-class marathon runners as Bill Rodgers, Dick Beardsley and Alberto Salazar, who set a world record Sunday in winning the New York Marathon in 2:08:13.

"There may be 25 top athletes and then thousands of average runners. They are running past the national monuments and the Capitol, through American history."

Phil Stewart, managing editor of Running Times magazine, calls the Marine marathon "a real mass-participation-type race. Because of the fact that they don't pay to bring top runners in, it has been a good opportunity for some of the not-so-well-known runners to win . . .There always seems to be a large number of people who are running slower times. If you're running it in four or five hours, you're not going to be all by yourself."

Among the leading contenders in the men's field are last year's winner, Michael Hurd, 35, who runs for the British Royal Air Force team; Dean Matthews, 26, of Atlanta, winner of the 1979 Honolulu Marathon, and Thomas Blumer of Cincinnati, who defeated Rodgers in a 10-kilometer race earlier this month.

The favorites among the women include Beth Dillinger of Blacksburg, Va.; Patricia Sher of Jacksonville, Fla.; Maddy Harmelinger of Merrick, N.Y.; Trudy Rapp of Alexandria; Ann Wright of Macon, Ga., and Rosalie Geuss of Arlington.

The field is a cross section of the population, ranging from cabinet members and congressmen to housewives, middle-level bureaucrats, military enlisted personnel, handicapped people, pre-teen youngsters and septuagenarians.

Bobby Beathard, the Washington Redskins' general manager who has run marathons in less than three hours, should have no trouble finishing in time for his team's 4 p.m. game against the St. Louis Cardinals. Agriculture Secretary John R. Block, 47, will attempt to improve on the time of 3 hours 6 minutes he logged in the Boston Marathon. Block runs between five and 15 miles daily for enjoyment and to relieve tension. He has been known to tell employes seeking appointments that they are welcome to run along with him and discuss whatever is on their minds.

In an effort to reflect the varied character of the field Sunday, The Washington Post interviewed eight marathon participants -- a marine, a United States senator, a housewife, a blind man, a government program analyst, a septuagenarian, a trade association executive and a dentist.

THE MARINE

Lance Cpl. Rickey Lamont Zayas, 22, is a trumpet player with the Marine Corps Drum and Bugle Corps, 8th and I streets SE, Washington.

"I want to enter the triathlon race in Hawaii next winter, and I'm interested in building my endurance," said Zayas. "It is something you have to plan for and train for. You have to eat right. It took me three months to work up my condition to run this marathon. I wake up early in the morning and around 6 or 6:30 I go out running for about an hour. I go out Pennsylvania Avenue SE into Maryland, past the cemetery and then back on Suitland Road and Pennsylvania Avenue."

Zayas is a native of Philadelphia, where he played football and rugby, ran cross country and wrestled at Cardinal Dougherty High School. He has been in the Marines for 3 1/2 years and is methodical in his approach to running; he keeps a diary in which he records his speed, distance and physical condition after each day's run.

In preparation for the Hawaii triathlon, which entails a 2.6-mile swim, a 112-mile bicycle race and a marathon, he has also been cycling and swimming. Zayas' uncle, Lamont Anderson, 41, a detective on the Philadelphia police force, is entered in the marathon Sunday and one of Zayas' aims is to beat him.

"I'd like to do the race in 2:35 or 2:40. A runner's body is something you have to take care of. If you are an athlete, the best way you can express yourself is by taking care of yourself."

THE SENATOR

Sen. Steven D. Symms (R-Idaho), 43, is a third-generation Idaho fruit grower and conservative congressman who unseated Frank Church, the veteran Democrat and Foreign Relations Committee chairman, in the 1980 elections.

"I find I can do my job better if I am in good physical condition," said Symms. "I played football in college, but the farthest I ever ran was 100 yards. Before I entered politics, I was active working on the farm. I took up running just to get in shape. This year, I decided I would try to get in shape to run the marathon. I've been averaging 36 miles a week, and I should be able to do the race in four hours or less. I'm looking forward to it. It should be a lot of fun, but I would not consider it a victory if I finished the race and then collapsed with cramps and had to go to the hospital."

Symms, an ex-marine, says he has managed to maintain his weight from his University of Idaho football days, 195 pounds.

"Running is a good sport for people who are busy, because you can run whenever you can fit it into your schedule. You don't have to meet someone at a particular time on the golf course or at a racquetball court. I keep a set of my running clothes in a locker at the Senate gym, another set at my home in Virginia and another set at my home in Idaho. If I travel, I take my stuff with me."

Symms says he has never run farther than 21 miles. He sometimes tends to get bored after about 10 miles.

THE HOUSEWIFE

Linda Grantham, 31, of New Britain, Conn., is the mother of four children and the wife of a Marine gunnery sergeant.

"This will be my first marathon. I started running because my husband is a runner and he got me to run with him. The Marines were always talking about running in the marathon and I thought it would be a nice thing for a Marine wife to do a marathon," said Grantham. "Basically, my goal is just to finish."

Grantham and her husband, Louis, will leave their children with a babysitter in New Britain when they come to Washington for Sunday's race, but he has not yet decided whether to run.

Generally, she runs between three and four miles a day, although in preparation for the Marine marathon she has increased her distances. "I find it very relaxing. It is a time that I have to myself. The rest of my time belongs to the house, the kids and my husband, but this is my very own time."

THE BLIND MAN

Alfred Maneki, 39, of Columbia, Md., is a mathematician with the Department of Defense and has been blind from birth, although he has a slight amount of vision in his right eye that enables him to see, for example, a car parked in front of him. But he cannot see an object on the road, a curb or a set of steps. He runs with a cane.

"It's not enough for me to be successful as a person," said Maneki. "It's more important for me to be successful as a blind person doing some kind of normal activity. It's getting out and showing that as a blind person, running is an organized type of activity that I can participate in. There really are ways that a blind person can adapt. To carry a cane is not something that I am ashamed of any more, but there was a time when I found that carrying a cane, advertising my blindness that way, was degrading.

"By no means am I a fast runner. I don't expect to win, and I'm not even sure I can finish. But I've been preparing for it all year. I'm just a mediocre runner who enjoys it. No matter where I finish or how far I go, there will be some sense of personal accomplishment."

Maneki, who holds a doctorate in mathematics, began running for exercise about 15 years ago while in graduate school in Chicago. About a year ago, some of his colleagues at work began talking to him about entering races.

"I entered a five-kilometer race and then a 10-kilometer race and then a half-marathon. I found I thoroughly enjoyed it. I guess I've just become sort of hooked on running with people," said Maneki.

THE PROGRAM ANALYST

Janet Thompson, 37, works in the office of toxic substances at the Environmental Protection Agency. She lives near Springfield and has been training in a park near her home after work. She has been running for about five years with the Washington RunHers Club, a women's organization that sponsors several road races for women. This will be her first marathon.

"I just got the marathon bug. I'm a slow runner. I predict my time will be about 4 hours and 30 minutes, but I would be really happy if it were only four hours," she said.

"Because I'm not a fast runner, I get no sense of accomplishment of running in a five-mile race in a time like 45 minutes. I feel like running a marathon is an achievement. It's something I'll be proud of."

Thompson worked as a volunteer at last year's Marine marathon, passing out water cups at the 24-mile mark. She says she noticed expressions of extreme fatigue and exhilaration on the runners' faces.

"I decided I could do it, too."

THE SEPTUAGENARIAN

Ed Benham, 74, of Ocean City, Md., began running at the age of 71. An ex-jockey, he retired in 1976 and moved to Ocean City after almost a half-century in a variety of jobs at race tracks. After his wife died, he found himself with lots of spare time; he took up running partly to fill the void. His first marathon was the D.C. Marathon last spring, which he finished in 3:32.

"A lot of people get old and retire and don't do anything. I do everything," said Benham, who has won several running titles in his age group. "I love beating the younger guys. Last Sunday, I ran in an eight-mile race in Baltimore and finished in 56 minutes. I run all the time.

"Once in a while, I run down on the beach, but usually I just run on the highway. I just keep going and going. My best time in a marathon was 3:32, but I'll be trying to beat that Sunday. It just depends on what kind of condition I'm in and what kind of course it is."

THE TRADE ASSOCIATION EXECUTIVE

Marc Himmelstein, 34, is senior executive branch liaison with the American Petroleum Institute. He will be running the Marine Corps Marathon for the second time. Himmelstein, former deputy assistant secretary for governmental affairs at the Department of Transportation, ran the 1980 marathon in 3:48.

"I ran the Marine Corps Marathon last year and just loved it," he said. "That's part of the reason I'm doing it again. It was a real high just to be out there running it. It's always nice to have people out there cheering you on. This city is such a beautiful city, it's nice to have a chance to run through it. There was one point in the race last year, out in East Potomac Park, where there was no crowd and it was quiet. The only sound was the sound of the runners' feet hitting the pavement. It's kind of beautiful to be able to be with a group and still be relaxed.

"I've been running for about five years, and I guess most runners, when they start running any distance, think of a marathon as something they would like to achieve."

THE DENTIST

Leslie Christian, 36, a Navy dentist stationed in San Diego, ran the Marine marathon last year in 2:36 and would like to improve on his time. A 1967 graduate of the Naval Academy, he spent five years as an aircraft pilot in the Marines before going to dental school at Case-Western Reserve University on a Navy scholarship.

"I started running when I was in dental school. It helped relieve some of the tensions and pressures. At first, I did three or four miles a day, but then I started increasing the distance. This will be my 14th marathon. I really like the Marine marathon. I guess I still have a soft spot in my heart for the Marines, but it's also a good course. I really love the course, the weather's usually pretty good and I have a chance to visit some friends."