Scorned by the U.S. selection committee for the World Kayak Championship, Theresa DiMarino consoled herself with three gold medals at the National Sports Festival.

The 19-year-old George Mason University sophomore from Alexandria, Va., cruised to the kayak singled title by more than a boat length today, then paddled No. 2 on the winning four-woman boat. Sunday, she had won the doubles with Nancy Leahy of Camp Springs, Md.

The singles start required two minutes, as the eight women field repeatedly inched off the starting platform. There was a loud cheer from fans along the Prospect Lake banks when the gun sounded.

"there was a lot of jockeying, because psychologically everybody wants that one inch," DiMarino said.

"I had a poor start, but I felt completly in control of the race."

There was considerable jockeying for berths on the U.S. team and DiMarino could not control her fate without paddle in hand.

"i was fourth in the world trials, but there's a lot of politics involved and one of the girls I beat went to Europe," DiMarino said. "i was very disappointed, because the politicking was so obvious. I trained so hard and gave up everything. I didn't work and I don't have much money because of it."

DiMarino will make a lot more sacrifices to train for the 1980 Olympics. Although only 5-foot-4 and 130 pounds, she played basketball for George Mason last winter. Not this time.

"i'll give up basketball and a semester if not a whole year for school," she said. "There is a tremendous amount of training necessary to reach the top I lift weights an average of four times a week and I run four miles a day.

"Training for Kayak is 10 times harder than basketball. Three hours of basketball practice doesn't compare to 1 1/2 hours of speed training. Upper body strength and endurance are the big factors."

DiMarino was an all-district runneer at Mount Vernon High and was a swimmer until age 11, when Glorianne Perrier, the mother of Washington Kayak racing, persuaded her to use a paddle instead.

"I looked at the boat and it was so big and I was so small, but once I tried it I gave up swimming," DiMarino said ("I have to compete. I have a brother 18 months older and we've always competed. The drive to win so strong.)

"Sometimes I think what am I doing to my life, but i'm only 19 and the average age of the women out here is 27, so i'd like to make three Olympics teams. I see these older girls and I tell myself i've got to go for it and beat them.

"With some things like school work I go through the motions, but when it's something I want to do I give it everything. One day I know all this training will pay off."