As she reached the top of the last hill of her five-mile run, Laura DeWald was hardly out of breath. Her second workout of the day was supposed to be easy.

DeWald, who lives in Arlington, is training for the first women's Olympic marathon next summer. But her concern now is today's Cherry Blossom 10-Mile, which begins at 8:30 a.m. and is expected to have 4,500 participants.

The men's race will feature two world-class distance runners and several top American runners. Four-time winner Bill Rodgers of Melrose, Mass. and Greg Meyer of Wellesley, Mass., the 15- and 20-kilometer American record holder, always provide a classic matchup.

Rodgers, who set the course record of 47:09 in 1980, was upset last year by Terry Baker of Hagerstown, Md. Baker will again run this year, along with Dan Gruber of Scott Valley, Calif., and Matt Wilson of Fairfax, who last year finished third and fourth, respectively.

DeWald, 25, will be challenged by defending champion Eleanor Simonsick of Baltimore, Anne Hird (formerly Anne Sullivan, who set the course record of 55:34 in 1980), 1980 Boston Marathon champion Jacqueline Gareau of Montreal, and Suzanne Girard and Pia Palladino of the Georgetown University track team.

Good competition is nothing new for DeWald; it comes with the reputation of being one of the nation's best. And although she has won throughout the country, she has yet to win a big race in this area.

Last fall, she made a serious commitment toward the 1984 Olympics. She quit her $22,000-a-year job as a civil engineer for Arlington County.

"Quitting my job was a tough decision," DeWald said. "I was sort of debating the move for at least a year, about the time when my running took off. My opportunities in running got better. I sat it out for a year to make sure it was a sure thing.

"But I'm glad I did it. I can see places I never would have been able to see if I hadn't quit my job. I like to travel. I miss the work, but I can always pick it up again. The financial part was not very important. I knew I'd get by without winning big races. I don't need the money because I'm living at home and Brooks (Racing Team) gives me certain benefits such as health care, equipment and living expenses."

DeWald began her running career in 1975 as a 2:29 half-miler at Washington-Lee High School. She started and captained the University of Virginia women's team. After being voted MVP in 1977 and placing eighth in the 1978 AIAW cross country championships, she sat out her senior year because of a conflict with the team's coach.

DeWald ran her first marathon in November 1979, leading the Marine Corps Marathon for 25 1/2 miles before fading to third place in 2:59:22.

A year later, DeWald ran second in the Marine Corps in 2:44.53. She began to receive national attention, but it wasn't until her 2:35.57 in the 1981 Boston Marathon that she was considered a serious contender.

In 1981 she ran the eighth-fastest marathon among American women, and was ranked 14th in the world (by Runner magazine) and 18th in the world (by Running Times) among women road racers.

DeWald began 1982 by breaking the national 20-mile record with a 2:02.01 in Greenbelt. She then had a taste of international competition in the Osaka Invitational Ladies Marathon in Japan. After leading for 22 miles, she dropped back and placed fourth in a personal-best 2:34.59, first among American women.

Said DeWald, "The race (Osaka) is put on in such a full scale. We had red-carpet treatment for a week. The people were so enthused. People would recognize me in the street and ask me for my autograph. They have a great attitude toward athletes. They treated us like celebrities."

When DeWald returned to the States, she was hampered by Achilles tendinitis, which caused her to drop out of the 1982 Marine Corps Marathon after leading for 19 miles. Two months later, she was back on track, breaking her own 20-mile national record. Her 2:00.39 still stands.

"I'm running 85-100 miles per week. I'm in a base period for the rest of the month, working toward the Avon (Invitational Women's) Marathon on June 5. Next month is hills and strength work. May will be speed work. Then I'll be ready.

"I'm hoping for a personal best in the Cherry Blossom. I ran a fast 10K (34:00 last January in the Orange Bowl 10K) without speed work. I want to beat the nationally ranked women coming in for the race."