In the Soviet Union, fresh fruit in the winter means a better workout. And new shoes, brought across the ocean by foreign friends, means a renewed running career.

At the invitation of American friends, Olga Markova and 1975 Soviet marathon champion Greg Vinjar have been running through Washington and competing in races on the Atlantic seaboard for the last month. Both will run the Marine Corps Marathon Sunday starting at the Iwo Jima memorial in Arlington.

Markova, 32, running her fourth marathon since switching from the mile three years ago, is one of the favorites for the women's title.

"The food here is more than better, food is a problem for Soviet athletes," said Vinjar, 43, her coach. "Vitamins give a little compensation, the rest is uncompensated. That's why many talented runners have problems in their careers."

Through the 1970s, Vinjar clocked times of 2 hours 14 minutes in the 26.2-mile race, winning the national title in 1975. He stopped competing and running 12 years ago until Marni and C.W. Gilluly took him a new pair of running shoes from the States last year. Sunday's race will be his first marathon in more than a decade.

"I had leg problems with my old shoes; with the new shoes, there is no problem," he said. "Now there is new problems -- how to run faster." He said he will be happy with a sub-2:48 clocking.

For the Soviet visitors, a training and racing trip to the United States is not only good for training because of the warmer weather and abundant fresh fruits and vegetables, it's beneficial for the soul.

"Having her here will be a good thing for her career, in all meanings," said Vinjar. They have worked closely for the last two years, when she approached him for help in long-distance running, and he often answers for her. To many questions, Markova told Vinjar, "You know the answer." She is shy and withdrawn -- a good thing for a runner, said Vinjar, since it allows for her aggression to come out in race settings.

As a "human being and a sportsman, these experiences are good possibilities for her," said Vinjar. "The preparation here makes a good job for her. All knowledge about the world will help her -- a sportsman is a human being. She has new horizons."

"It's really been an eye-opener for her," said Marni Gilluly. "She's always commenting how friendly everyone is, how willing they are to help her out."

She's hesitant to commit to a specific time or finish, but Markova is hoping this trip will give her necessary international and competitive experience to launch her to the top levels of marathon competition back home. Her progression has been remarkably steady. "I progress like a machine," she said. Two years ago she ran 2:42 in her first marathon and last year dropped to 2:40 -- the 16th-best time in her country. In May she ran 2:38 in Hamburg.

"It's not easy to put all the things on the shelves," she said, "there are too many new things there now." Coach and athlete are planning for a 2:32 in 1992, which probably won't be good enough to make the Olympic team.

"We didn't plan for the 1992 Olympics, she's too young as a marathon runner," said Vinjar. "Marathon plans need more long preparation."

Vinjar knows plenty about preparation, goals -- he calls them tasks -- and rewards. He hasn't received any rewards for running for a long time and hasn't had any tasks to perform either; the only ones he hopes to reap Sunday are personal ones. It will be the first race he's ever run solely for enjoyment.

"I am not a professional runner as before, I only run for pleasure now, for my spirit," he said. "When I left, I didn't miss competition. . . . I had no problem with leaving. I just came back to it because I liked it. It is like looking at the same point but from a different point of view.

"Now, since I am not a professional, it is interesting for me -- how to compete without the pushing of my professional position. I'm free of those problems but I'm free to compete. Before, I had 11 professional marathons and during every one I had a certain task, a certain purpose and I tried to do everything I could to solve the task. Maybe that's why I never slept after those races -- I gave all I had.

"Perhaps the competitive spirit lives inside but it doesn't have the task to win every case."