In April, Chuck King tore ligaments in his right ankle playing basketball in gym class at Edgewood High School. Yesterday, that injury paid dividends as King, from Abingdon, Md., defeated Washington, D.C., native Jeff Loman, 152-124, to win the 10th annual Youth Duckpin Invitational at Fair Lanes Hyattsville.

King's injury put him in a walking cast for two weeks. During that time, he bowled a 201, which was the season high for his Greenway Bowling League.

"I had to change my normally four-step approach to a three-step one," he said. "Four steps was just too far to drag the cast, and the new approach gives me a lot more control of the ball because it slows me down."

King, 17, was moving at the correct speed when he faced Loman, who is four years older. King, in his third appearance in the Invitational, scored a spare in his first frame and followed that with a strike in the second.

After three frames, he was in control, 57-24. Another spare-strike combination in the fifth and sixth frames increased his lead to 105-70, and the title soon was his.

In the girls division, Ann Ogle, 15, joined Beth Yingling (1981) as the youngest champion ever. Ogle, from Westminster (Md.) High School, cruised past Falls Church's Sandi Erickson, 138-116.

This is the first time Ogle has qualified for the Invitational, which selects the top 80 boys and 56 girls from the District, Maryland, Virginia and West Virginia, based on seasonal averages.

Ogle averaged only 116 during the season, but she averaged 134 during the early rounds.

"I can't really explain it, except that I've had pretty good lanes," said Ogle, who got past Stacey Palmer of Parkville, Md., in a 20-frame semifinal, 301-298. In that match, Ogle scored a strike in the 19th round and a spare in the 20th.

Her final against Erickson was not nearly as perilous. Ogle hit a strike-spare combination in the third and fourth frames to take a 46-36 lead.

When Erickson rallied with a strike in the fifth to go ahead, 69-61, Ogle answered with a strike for an 83-69 lead.