More than 25 years after what he calls a terrible college track career as a middle-distance man, Sal Corrallo began cutting a wide swath through the AAU record book. He has set national age-group marks in race walking at distances of 5, 10, 15, 20, 25, 40, 50 and 100 kilometers and estimates he holds "about 15" records altogether.

Corrallo, 51, of Arlington, says he was so chronically injured his senior year at the University of Buffalo that he found himself coaching instead of running. Now he says, "If I want to have fun, I run a race. I like the ambiance of races."

Corrallo runs for the Potomac Valley Senior Track Club, an organization of 400 men and women who are AAU masters (age 35 and older). The first club of its kind in the Washington area, PVSTC was founded 10 years ago. Corrallo was its president 1978-1981.

Many PVSTC members have returned to running after layoffs of 15 to 20 years. Corrallo's renaissance began in 1974 with a daily walk from Union Station to his office at Fourth Street and Independence Avenue SW. The 1 1/2-mile walk evolved into an occasional jog, and when his wife became ill, he started running more seriously in order to cope with the stress. After her death, PVSTC became his "social life" and he began spending time running with his three children.

Now he commutes at least one way each day on foot, either walking or running the 10 miles between his home and his office at the Department of Education.

In 1975 Corrallo took up race walking to complement his long-distance running. He says walking is "virtually injury free," although he has some lower back problems resulting, he speculates, from a 100-kilometer race. He says race walking involves only a third of the stress to the joints that running does and provides conditioning for the entire body because of the demands placed on the arms and shoulders.

Corrallo, whose training is a mixture of running and walking, ranks himself as "sixth or seventh" among area masters runners, but as a walker he is unchallenged.

On May 16 he set a national record for 51-year-olds in the TAC 50-kilometer championships held here on a warm and humid day. His time of 5 hours 7 minutes was almost seven minutes faster than the old record, but when he crossed the finish line to the cheers of teammates, he was disappointed. He had planned to go 20 minutes faster but was slowed by the heat.

Corrallo also holds records in the 50 kilometers for ages 47, 48, 49 and 50.

Not all Corrallo's achievements are measured by the hip-wagging gait of the race walker. As a runner, he has qualified for the Boston Marathon with a 3 hour 16 minute finish in the George Washington Birthday Marathon. The key to his running success: Corrallo walks during part of the races.

Corrallo's marathon strategy is to break into a brisk race-walking stride for five minutes every half-hour, allowing his muscles to stretch without cooling.

He says that it's critical "to do it in the beginning even if you don't feel tired." He adds proudly that of the crowd that passed him during his first walk, he "caught 80 percent of them by the end of the race."

The gospel of mixed walking and running is one of Corrallo's causes. Another is the incorporation of walking into school track and field programs.

"It has to start there," he says, "but they (officials and coaches) are afraid of it because they don't know anything about it. But it's no different from throwing the javelin or hurdling; you just have to learn how."

Wisconsin and New York are the only states that include walking in high school competition. Many of the world-class walkers in the United States have come from these programs.

In the interest of converting some of Washington's runners (and sitters) to the joy of walking, Corrallo and the rest of the PVSTC race-walking division hold clinics every Wednesday evening on the Mall.

"Lots of people come once, pick up the basics, and then we never see them again," Corrallo says. "But that's okay. The basics are all you need if you want to use walking as a training tool."