In Denver, mine workers walked picket lines with the Denver Broncos.

In Pittsburgh, steel workers offered striking Pittsburgh Steelers free use of their union offices and a bank of 15 telephones.

And in Washington, food and commercial workers printed T-shirts for picketing Washington Redskins reading, "An Injury to One is an Injury to All."

Across the country last week, the word went out to unionized workers of all stripes to support striking football players. And as negotiations between players and National Football League owners bogged down, some union executives were beginning to talk about boycotting proposed games played by replacements, as well as shutting down some operations at football stadiums if the strike continues.

The possibility of millions of unionized Americans lining up against football owners may be only a dream in the higher echelons of the AFL-CIO. But the building reaction of unionists to recent developments in the NFL illustrates at least one important change that has taken place in the sport since players last went on strike in 1982.

In the intervening years, the NFL Players Association not only joined the AFL-CIO but saw its executive director elevated to that group's elite, 35-member executive council, with potential access to 13.1 million union members, ranging from punch press operators to airline pilots.

Striking players have only begun to call on other unions for support. But with the spectre of owners busing in non-union players to stand in for striking regulars, some union leaders say they don't need much prompting to jump into the fray.

"One of the more savvy things the players did in the last five years was to get themselves involved in the union mainstream and obtain allies," said Phil Sparks, spokesman for the American Federation of State, County and Municipal Employes here, which represents between 500 and 1,000 football stadium personnel nationwide. "They won't be out there fighting by themselves."

Whether the players and their supporters in other unions could succeed in mobilizing the rank and file of organized labor remains to be seen. Like many other fans, some union workers are wondering what football players who make an average $230,000 a year have to complain about.

According to leaders of other unions, though, many of the issues involved -- pension benefits, the right to choose one's place of employment, for instance -- are common to all workers.

"I don't think our members identify with the salaries. It's the issues. Whether he's a plumber or whatever, the issues are the same," said Michael Calendo, business manager of the District 8 Lodge of the International Association of Machinists in Chicago.

Since its inception, the players association has tried to look and act like a union. Its approximately 1,550 members pay regular dues of $2,400 a year, and their elected leadership negotiates with football owners for a contract spelling out working conditions that apply leaguewide.

But after the 1982 strike, which kept players off the field for 57 days, association executives began to look for more muscle-power. They went to the AFL-CIO, an umbrella group for 89 unions.

"We had lots of difficulties going up against the power of the NFL on our own," said former players association executive director Ed Garvey, now an attorney in Madison, Wis. "We felt that if we could be part of the AFL-CIO, it would help in many ways. Not just in a work stoppage, but in research and other kinds of support. And we were right."

By joining the union giant, the players association gained access to union-leadership training for player representatives at individual teams, contacts with other unions and the national network of strike support the AFL-CIO can muster almost instantly.

In return, players have lent their prestige and visibility to organizing and other kinds of activities at affiliated unions. They have also walked picket lines with other striking unionists.