Celtics by the sea

Hopefully no Boston Celtics players showed up to the first day of practice assuming coach Doc Rivers was going to take it easy on them. By the time media were allowed in the gym at Salve Regina University’s Rodgers Recreation Center, guys looked flat-out exhausted — some more than others.

It was easy to understand why. Tuesday’s practice went nearly three hours.

“It was a long practice,” Rivers said.

The workout seemed to take its toll on center Shaquille O’Neal. As the team ran full-court transition offense drills near the end of practice, O’Neal was a bit slower than usual getting up and down the floor. And while other players caught the ball near the hoop and dunked it, Shaq opted for a layup each time, barely leaving the ground in the process.

“Shaq looked great,” Rivers said. “Mostly everybody made it through practice. I thought, the last hour, you could see that they had run three hours.”