On the first day of a strike of the baseball exhibition games, many of the major league players throughout Florida and Arizona engaged in supervised workouts at their own expense at their teams' official spring training camps today.

But while many of the players (only the Montreal Expos abstained as a team) were rounding into shape for the regular season, which they say will open as scheduled April 9, the two sides negotiating a new basic agreement were moving further apart.

The April 1 deadline for the Major League Players Association's modified proposals has passed, and they are no longer on the bargaining table. That means, for example, the time period of five years before a player can opt for free agency reverts back to the initial proposal of four years and the minimum salary proposal moves from $37,500 to $40,000.

Marvin Miller, executive director of the players union, and Ray Grebey, chief bargainer for the 26 owners, are scheduled to meet in New York Thursday for their second session with federal mediator Kenneth E. Moffett. t

Both Miller and Grebey were angry in the wake of Tuesday's decision by the union's executive board to strike the remaining 92 exhibition games and set a regular season deadline of May 22.

Grebey, in New York, criticized the players association for not officially notifying the owners of the exhibition season strike. "In all my years in this business, that's never happened before," Grebey said.

Miller, in Dallas, was critical of the owners' refusal to provide expense money for meals and hotels for the players working out on their own at the teams' spring training complexes.

"First, those expenses will be apart of any settlement," Miller said from his New York home. "Second, I'm perpetually astonished that businessmen can be so small. For a couple of hundred dollars, they're taking the risk of alienating the players and making any setlement that much more difficult.

"It's lunacy . . . unless they're trying to provoke a strike," Miller added. "In that case, it's very smart. They'll succeed."

Bowie Kuhn, commissioner of baseball, expressed optimism that negotiations over a new basic agreement would be settled through collective bargaining.

"I am glad the season is going to start on time," said Kuhn. "That seems best for everyone, especially the fans. As far as the negotiations, I have felt right along that continued work at the bargaining table will result in a new agreement."

The owners' Players Relations Committee had said Tuesday night that the camps would remain open to players desiring to work out. But "since the individual player contract requires that players will appear in scheduled exhibition games . . . meal money, allowances and hotel costs will not be paid."

At the New York Yankee camp in Fort Lauderdale, Fla., only Lou Piniella, Ken Clay and Fred Stanley were missing for the 2 hour 15 minute practice session. None of those absences was thought to be connected to the strike action.

In Mesa, Ariz., all but one of the Chicago Cubs -- Dave Kingman -- showed up for a preworkout meeting at the club's spring training camp.

Kingman called Bob Kennedy, Cub general manager, and told him he would not be there, giving no explanation.

Fifteen Cubs participated in workouts conducted by Bill Buckner.

The Expos had their coaches ready to supervise a workout but Steve Rogers, the team's player representative, met with his teammates and about half of them decided to go home and work out on their own, according to team publicist Richard Griffin. Griffin also said the remaining players said they would work out only if the coaches left the field. The coaches, did not leave and there was no workout.