A panel of witnesses, including players, former players and a labor leader, urged a congressional subcommittee yesterday to investigate charges that the National Football League discriminates against blacks in the hiring of head and assistant coaches.

Citing a study that alleged a pattern of discrimination over a 20-year period, William Pollard, director of civil rights for the AFL-CIO, told the House Committee on Education and Labor's subcommittee on employment opportunities that the study's findings "should convince a sensitive and objective person of the need for corrective action."

In Janurary 1981, Pollard convened a panel to examine the study, which was commissioned by the NFL Players Association and done by Jomills Braddock II, a sociologist at Johns Hopkins University in Baltimore. Based on examination of NFL data and records of more than 5,000 players between 1960 and 1979, Braddock concluded that "race does matter in managerial recruitment in professional football."

In the years covered by the study, a total of 261 assistant coaches and 68 head coaches had been hired from the ranks of NFL players, but none of the head coaches was black and only 20 of the assistant coaches were. Twenty-six percent of the players in that time frame were black. The percentage is now slightly more than 50 percent.

Jack Donlan, executive director of the NFL's Management Council, the league's labor negotiating arm, declined to make an appearance before the committee, saying it would be harmful to ongoing contract negotiations with the NFLPA.

In a letter to committee chairman Rep. Augustus F. Hawkins (D-Calif.), Donlan said, "The National Football League's member clubs have a sincere interest in providing opportunities for the employment of more blacks and other minorities in administrative and coaching positions."

NFLPA president Gene Upshaw told the committee that black players are often shifted away from the four "leadership" positions--center, offensive guard, quarterback and linebacker--which the Braddock study identified as supplying the bulk of the potential coaching pool.

"Just how is one assigned a position on a football team, Mr. Upshaw?" asked Rep. Millicent Fenwick (R-N.J.).

"It does depend on size," said the 6-foot-5, 255-pound Upshaw, an offensive guard with the Oakland Raiders. "And then they throw in some variables, like how fast you can run."