Asserting that the signing of Herschel Walker could lead to a full-scale raid on college athletes by professional sports leagues, Sen. Arlen Specter (R-Pa.) introduced legislation yesterday that would give the leagues a limited antitrust exemption to enforce restrictions on recruiting collegians.

"The Walker case could lead to a stampede if the longstanding rules are not reinstated and preserved," Specter said.

Walker, winner of the Heisman Trophy as a running back at Georgia, passed up his senior year to sign a reported $5 million, three-year contract last week with the New Jersey Generals of the new U.S. Football League.

Commissioner Chet Simmons said one of the reasons he approved Walker's signing was that the USFL had been advised in two legal opinions that restrictions on signing undergraduates violate federal antitrust law.

The National Football League, which limits undergraduate signings by its member clubs, has acknowledged that its policies, too, are subject to a court challenge.

Under Specter's measure, there would be no new rules established by Congress, but the sports leagues would be free to enforce their own limitations on member clubs.

Specifically, the legislation says that federal antitrust laws "shall not apply to a joint agreement by or among persons engaging in or conducting the professional sports of football, baseball, basketball, soccer or hockey designed to encourage college student-athletes to complete their undergraduate education before becoming professional athletes."

Said Specter, "Certainly there is a substantial public interest in a policy favoring rules which encourage athletes to finish college. There are many examples of collegians who have been lured by the big bucks of professional athletics to leave school who later sustain injuries and spend the rest of their lives regretting their decision . . ."

David Berst, director of enforcement for the NCAA, said he was unfamiliar with Specter's bill and had no immediate comment. NFL Commissioner Pete Rozelle said "we would want to talk to Sen. Specter and also review the language of the bill" before commenting.

Ed Garvey, executive director of the NFL Players Association, said, "I'm sure we'll want to take a look at it." But Garvey noted that "baseball, hockey and basketball have lived quite well with rules requiring only high school graduation."