Defending Eastern Conference champion Celtics open training camp in Newport, RI

East champ Celtics open training in Newport, RI

NEWPORT, R.I. — Doc Rivers doesn’t want the Boston Celtics to think that they can coast through training camp just because they have loads of experience.

He made that clear with a three-hour practice on the first day of training camp.

“We’re not going to let the ‘veteran’ thing be an excuse not to work,” Rivers said after putting the defending Eastern Conference champions through an extra-long workout in a sweltering gym at Salve Regina University. “Experience is great, but we’re not going to use it as a crutch.”

The Celtics opened a weeklong training camp on Tuesday at this seaside school nestled among the famous mansions that had been summer homes to the Vanderbilts and tobacco heiress Doris Duke. But the luxurious offerings didn’t include air conditioning for the gym.

“Way too warm,” the coach said. “Felt like the Garden in the ’80s.”

Rivers said the heat wasn’t an attempt to make his players sweat, the way Red Auerbach was accused of raising the temperature in the old Boston Garden to make it uncomfortable for opponents. (Auerbach denied it, pointing out that there was simply no air conditioning in the building.)

But Rivers said the workout was a good first start for his players after a long summer away from basketball.

“They’re not in bad shape at all,” he said. “But they’re not in Celtics shape. I told them that.”

Countered Kevin Garnett: “No matter how good of shape you’re in, you’re never in Doc Rivers shape.”

The Celtics, who won their unprecedented 17th NBA title in 2008, reached the finals again last season before losing in seven games to the Los Angeles Lakers. With Paul Pierce and Ray Allen, along with Rivers himself, all free to walk away, there was talk that the window had closed on the aging Big Three that had restored the once-proud franchise to its former glory.

But Pierce, after opting out of his contract, signed an extension; Allen barely dipped his toe in free agency before re-signing with Boston, and Rivers, who had considered taking a break to spend more time with his family, decided to come back for a run at another title. Them they added Shaquille and Jermaine O’Neal and Delonte West to an already experienced team.

“They seem like they’ve been here the whole time,” Allen said after their first practice together. “Whether you’re 20 years-old or 30 years-old, it’s important that we’re all thinking with the same mindset.”

Garnett missed the 2009 playoffs, costing the Celtics a chance to defend their title intact. He said he felt good getting back on the court without limitations after spending most of the past season strengthening his knee.

Jermaine O’Neal played with the first team in the first practice, filling the spot held by Kendrick Perkins, who was injured during the finals and isn’t expected to be back until February. Perkins shot free throws and strolled around the perimeter of the court without an obvious limp, barking out encouragement to his teammates.

Shaquille O’Neal said he would have no trouble adjusting to his role with his new team, saying he expected to play 20-25 minutes a game.

“My game is real limited. I know to look for Garnett; I know to look for my shooters. I’ve always played with great shooters,” he said.

“I’ve had an unorthodox, illustrious career,” he said, leaning back on the bleachers. “Unorthodox. Illustrious. Two big words in a row.”