In an atmosphere reminiscent of a preseason training camp, Jeff Ruland and Frank Johnson rejoined the Washington Bullets and participated in a spirited two-hour workout yesterday to prepare for their Wednesday NBA playoff opener against the 76ers in Philadelphia.

Ruland, who has been inactive since Feb. 1 with a strained right shoulder, and Johnson, out since Feb. 7 with a broken bone in his left foot, were placed on the team's active 12-man playoff roster. Ruland said he was ready to play against the 76ers. Johnson said it is too early to tell about his status for the best-of-five series.

To make room for the two, the Bullets dropped swing man Guy Williams and guard Tom Sewell from the playoff roster. The club retained future rights to both.

Yesterday's session was lively and filled with several jolts. The first involved the number of bodies present. After struggling with injuries over the last two months, there were actually 14 players on the floor at Bowie State College.

The most important jolts were given out and received by Ruland. Unlike the last month or so, when his shoulder limited him to shooting alone while his teammates practiced, the 6-foot-10 center took part in all the team's drills, showing no ill effects from his extended inactivity. A week ago, he received an injection to relieve inflammation in his shoulder.

Shortly before practice, Ruland gave a forearm shot to Rick Mahorn, who did nothing in response. That didn't last during full- and half-court scrimmages, however. The physical contact exhibited by the two men was described by General Manager Bob Ferry as being "like puppy dogs playing." Surely the breed was Great Dane, with a pinch of Doberman thrown in.

In Ruland's eyes, the contact wasn't as important as being able to carry out the other facets of the game. Any questions about the center's ability to extend his right arm were answered by a pair of running, reverse slam dunks. Asked which was a clearer sign of his recovery, the contact or the dunks, Ruland jokingly said, "The dunks, because they were more stylish."

At the conclusion of the practice, Ruland pronounced himself fit. "It's not like I'm resting up for something. We've got another practice where I'll try to get some timing back and then I'll be ready to go," he said. "It's been so long, it felt great being out there. I'll put some ice on it (his shoulder) now, but it really feels fine."

That was enough to put a smile on Coach Gene Shue's face. "I don't know how effective he'll be, but it's very nice having him back. I think he can be productive," Shue said. "All this is very, very nice. Jeff finally worked out. I just hope he goes home and feels good."

Shue said jokingly that against Philadelphia the team "will try to win with numbers. I think we'll start seven players."

There was no joking about Sewell and Williams, shelved while late-season acquisition Don Collins, a veteran, was made playoff eligible.

"Tom and Guy are still every bit a part of the team. They'll travel and be with us the entire way, but these moves just make sense," Ferry said. "I believe in what Oral Roberts says, 'Expect a miracle,' especially with the way these series stretch out. Suppose Frank (Johnson) is ready in two weeks. If he can play we want him in there. Even if Jeff or Frank couldn't play, we were in a situation where Guy or Tom weren't going to be getting any meaningful minutes anyhow."

Johnson, who recently had the cast removed from his foot, did some light running during the practice and engaged in a pair of one-on-one games with Sewell and Dudley Bradley. Johnson didn't speculate whether he would dress at the start of the 76ers series.

During yesterday's practice, the team worked on defensive schemes to neutralize the 76ers' offense and planned ways to stop the series from becoming up-tempo, a scenario that would favor Philadelphia. "Keeping the score down is very important to us," said Shue. "We aren't necessarily going to walk the ball up the court all night but . . . "