Even in the jet age, a 55-hour trip is a pretty brisk pace for a U.S. Secretary of State.

How does George Shultz do it? Also: Why?He does it by relying on what appear to be enormous reserves of energy. But why did he decide to sweep through Guatemala, El Salvador, Honduras and Costa Rica in his first trip to the region since 1986?

Some senior members of Congress are puzzled. Is Shultz trying to lay the groundwork for a new U.S. drive to win support for the Nicaraguan rebels known as Contras?

And why did he ignore appeals from the Nicaraguan leader, Daniel Ortega, that he stop in Managua?

A senior official who briefed reporters before Shultz's departure Wednesday said renewed aid for the Contras would not be a major focus of the trip.

Shultz apparently shunned Ortega because U.S. policy calls for avoiding Sandinista leaders until they display what the Reagan administration regards as serious interest in moving toward a democratic system.

From Ortega's perspective, that would be a lot easier to do if the United States stopped trying to overthrow the Nicaraguan government.

Sandinista leaders have been appealing to the Contras to resume peace talks, but the Contras say the Nicaraguan government would have to take certain steps first.

These include granting permission to open a television station not run by the government, allow the taking of public opinion polls, declaring a general amnesty and suspending military recruitment.

And so, round and round they go, with the prospect of renewed fighting always there.

Peace talks ended June 9. The cease-fire has lasted three months, but the thousands of Contra soldiers who took sanctuary in Honduras during the lull may be ready to fight again. They are rested and have received food, clothing and medicine from the United States.

Shultz hopes the leaders of Guatemala, El Salvador, Honduras and Costa Rica will pressure Nicaragua to take a more flexible position on peace talks with the Contras.

U.S. aid to the rebels ended Feb. 29, and the mood on Capitol Hill is strongly against a resumption. Ostensibly, the administration is trying to decide what to do. Conservatives on its right flank do not want to see the Contras forsaken.