Fatigue played a major role yesterday in helping the Washington D.C. boys basketball team win a championship and in dooming the D.C. girls team to second place in the 16th annual U.S. Youth Games.

Fred Cunningham Jr. and Sherman Douglas each scored eight points the first half in leading the boys to a 16-point halftime lead en route to a 75-52 triumph over a tired Baltimore team at Georgetown's McDonough Gymnasium.

In the girls final at McDonough, Boston got untracked in the second period and won, 46-34.

Both Baltimore and Washington had played earlier in the afternoon and won their consolation finals to earn a second shot at the title in the double-elimination tournament, Washington beating New York, 57-42, and Baltimore outshooting Birmingham, 81-64. The winners had about two hours rest between games.

The boys championship game climaxed a three-day sportsfest involving more than 1,000 youths aged 9 to 15 from 12 cities. New York and Washington had the most impressive showings, finishing among the leaders in all five sports: basketball, track and field, bowling, swimming and tennis.

Washington's triumph in basketball wasn't surprising. After a seventh place finish last year, Coach Oscar Phillips fashioned a quick, skilled and determined team that outclassed the rest of the field. It had defeated its previous four foes by a total of 78 points, beating the Baltimoreans by four points Friday before dazzling them yesterday.

"We ran the whole game because we knew they (Baltimore) were tired," Phillips said. "Baltimore played us tight the first game and we were a little more determined the second game."

The girls team was determined, too, but didn't have the energy to keep up with quicker Boston. After a scoreless five minutes, Boston, led by Robbin Christian, Delores Williams and Michelle Edwards, got two scoring spurts in the middle two periods to take a 10-point lead and coast.

"I was tired when I went on the court," said Washington's 6-foot-1 Donna Harrington, who had 14 points and 14 rebounds. "I knew in the beginning it was going to be a long day. That was our fifth game in two days."

Except for a scattered triumph here and there, the track and field competition was a New York-Washington duel. In the six relay events, New York finished first in five and second in the other. Washington won one and was second in five.

In the 14-15 age group, Washington's Robert Thomas and Charlene Jackson won their 100 meters, Byron Carrington won the 200 meters, Lloyd Bacchus and Boris Goins won the long jump. Martin Walker, Sean McLaughlin, Wesley Rouse and Tyrone Jackson won the 400-meter relay in the 12-13 group.

The Youth Games conclude today with a breakfast and awards ceremony at the Shoreham.