A Nordic ski racer, unlike a downhill racer, can remain at top form for many years - a valuable commodity in the Olympics, where competition only once every four years often can leave an athlete peaking a little too soon or too late.

This may be the single factor that secures a medal for the United States in Nordic skiing at the Winter Olympic next February at Lake Placid, N.Y.

Bill Koch (pronounced "coke"), 23, of Guilford, Vt., has a good chance of repeating his feat of 1976, when he became the first American to win a silver medal in the 30-kilometer cross-country Olympic race.

Koch's skiing slumped the next two years, but he came back this season and is ranked among the top 10 cross-country skiers in the world.

"The ranking is informal: the World Cup races do not attract enough Eastern European racers on a consistent basis to be an accurate reflection of world ranking.)

Koch is not the only medal hope for the Nordic team. Alison Owen-Spencer, 26, of Anchorage, Alaska, was seventh in women's Nordic World Cup standings last season after winning the first race in the series - the first time an American woman had won any international race.

Later in the season, Owen-Spencer repeated her feat, taking first place in a World Cup race in East Germany. This was a greater test of skill, because she did it against the East Germans and Russians, who dominate women's cross-country skiing.

Ski jumping also offers hope for the United States. The team's top jumper is Jim Denney, 21, of Duluth, Minn., third in the 90-meter jump atthe pre-Olympics in Lake Placid in February and 1978 winner of the 70-meter competition at the World Championships at Lahti, Finland.

John Bower, director of the U.S. Nordic Ski Team, predicted both men would make it to the top 10 in the Olympics, and Owen-Spencer would make the top 15.

"She does not have as many years experience," he said.

"I wouldn't predict a medal for anyone in any sport," he said. "If they're lucky, they will win a medal. But about 25 other competitors have the same chance; it's that competitive. It depends on who is healthiest, who has the bext wax and whose breakfast set best," he said.

Cross-country races in the Olympics include the men's 15-, 30- and 50 kilometer races, men's 40-kilometer relay, women's 5- and 10-kilometer races, women's 20-kilometer relay, men's 70- and 90-meter jumps and men's Nordic combined (70-meter jump one day and 15-kilometer cross-country race the next).

The Nordic combined is scored by an elaborate chart that converts cross-country race times on the 15-kilometer course to points. These are added to the points jumpers who on the 70-meter jump.

Bower said competition is tight in Nordic skiing. The favorite for cross-country is Oddvar Braa of Norway, who came in first at the pre-Olympics and won most of the races in Scandinavia in February and March.

In jumping, Joachen Dannenberg of East Germany "is as good or bad as anybody," Bower said. He also likes Jouko Tormanen and Pentti Kokkonen of Finland, Johan Saetre of Norway and Harold Duschek of East Germany.

In the women's cross-country races, Bower said the Russian team is outstanding.

"There are probably 10 skiers on the Russian team who could crack the top 10 or 15 in the world," Bower said. "Fortunately, they can only enter four in the Olympics."

Bower said Raisa Smetanina, Galina Kulakova and Zinaida Amosova are the best Soviet women and should make the relay team formidable.

He attributed Russia's excelence in women's cross country to greater emphasis on their training there. He said the U.S. is in a par with Scandanavia in women's training, but our program for men still lags.