BEIJING - The United States must win gold medals outside its favorite two sports if it hopes to stay ahead of China and Russia at next year’s Beijing Olympics.

The Americans have traditionally topped the medal table by dominating the two high-profile Olympic events — track and field and swimming. That won’t be enough.

“Our effort has to be to gain medals in a more diversified fashion rather than relying on just two sports,” said Steven Roush, chief of sport performance for the United States Olympic Committee.

Roush, who will be in Beijing this week with a team of American athletes, acknowledged what many others have suggested: China may displace the United States as the top gold medal team when the Olympics open a year from now — Aug. 8, 2008.

“The Chinese have shown that they are capable of overtaking us in gold medals, and potentially in the overall medal count,” Roush said in a telephone interview earlier this month. At world championships, or other top international competitions in 2006, Roush said China won 43 gold medals with 36 for the Americans and 35 for Russia.

“Two years out they are already showing their capability of winning the gold medal count, and that’s without the benefit of hosting the Olympics and the bump that comes with it,” Roush said.

The United States won 36 gold medals in Athens in 2004 with 32 for China. The Americans had an edge of 39 medals in the overall count. The Americans won 102, followed by Russia (92) and China (63).

Of the 36 gold medals, the United States won 20 in two sports — track and field and swimming. China won 21 golds in five disciplines — badminton, table tennis, diving, weightlifting and shooting.

Roush said the Americans hoped to pick up medals in nontraditional disciplines like cycling, shooting, rowing, archery and fencing.

“These are sports with multiple-medal opportunities where we’ve traditionally been spotty and where we hope to improve,” he said. “It’s changed our strategy somewhat, not just because of China but because of the growing parity and the number of nations that are winning medals.”

He said China, which has dominated sports like table tennis and diving, would try to add medals in shooting, track and field and cycling.

“It shows it is a changing dynamic and China has arrived as a sports superpower and we now will have to refine our game to match the investment they are making,” Roush said.

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He said the Untied States Olympic Committee spends about $50-55 million annually on elite athletes. He estimates that China spends twice that much on its top athletes.

“As is general in sports, when you are on top everyone tends to shoot for you,” Roush said.

The Americans and several other teams are employing researchers to study the effect of Beijing’s filthy air on elite athletes. Roush said the Beijing air was a “little bit smoggier than the Los Angeles area” with heat and humidity similar to Athens.

“People training in clean air need to at least be prepared for some of what they can expect,” Roush said. “We did the same on the heat and humidity elements for Athens.”

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Chinese officials have told the International Olympic Committee that 1 million vehicles will be taken off the road in August when 11 test events are held in Beijing. Similar measures are expected during the Olympics.

Roush said the United States has also been assured about plant closures during the Olympics.

“They’ve have told us the factories will be closed for three months in 2008 and that they will have a directive to encourage residents to stay off the roads with their cars,” Roush said.