WALTHAM, Mass. -- When the curtains go up and reporters are able to view the final moments of Boston Celtics practice, the team is almost always engaged in 5-on-5 work to close out the session.
The Celtics finished a spirited two-hour session by running no-dribble, three-man weaves up and down the court, players sprinting from one end to the other -- tagging a coach's hand -- then racing back in the opposite direction while being unable to put the ball on the ground.
Asked about the session, head coach Doc Rivers noted, "It was long and it was a ton of running. That was done on purpose."
It wasn't hard to read between the lines. Rivers isn't particularly thrilled with his team's conditioning and overall game shape, so he put them through a different sort of Boston Marathon.
As Rajon Rondo declared after the practice, "We got up and down a lot more than usual."
And the ball rack got less use than usual.
"You have to be in shape first," Rivers said. "We can have all the intensity you want, and I think some of our guys do, but then after three minutes, when your lungs hurt, you're no longer thinking about intensity. You're thinking about survival. 'How can I get through these next five minutes?' And you're not playing the same.
"I think some of our [struggles are] conditioning and we have to get in better shape. And some of it is we have to be a more physical team, and maybe that's conditioning as well."
Rivers expressed disappointment in watching his team get pushed around against the Indiana Pacers in Friday's loss, which snapped a four-game winning streak. In a gruesome offensive game, Rivers felt like the win was there for either team to snatch, but the Pacers seemingly had more energy and pushed the Celtics around at critical moments.
Asked point blank if his players are close to being in his desired game shape, Rivers offered little to suggest they are.
"I don't know if we're close," he said. "I don't know the answer, but I know we're not. I don't know when we will be, but I know we're not."
So the Celtics spent the day running a relay race.
Rivers isn't putting all the blame on his players. He understands they got thrust into a tough situation. As he explained, after the NBA Players Association decertified during the lockout, most players likely anticipated the potential that there would be no season (or a January or February start at the earliest).
Instead, a deal came together quickly and the NBA cooked up a condensed 66-game schedule tipping off on Christmas Day. Players were in camp a week after the deal was consummated and didn't have much time to prepare for the season.
Rivers also blames himself for not putting his team through more conditioning drills during training camp, wondering now if he put too big a focus on installing offensive and defensive sets while ignoring his team's need to get its wind back up after a five-month lockout.
"That's where we're kind of learning on the fly here," Rivers said. "I learned that just watching them play the last couple of games. I just thought, 'Wow, we're tired after three minutes, four minutes.' So that's a lesson learned."
But another lesson is that it won't be tolerated. And if that means running suicides until his players' lungs burn so that they don't flare up during game situations, Rivers is prepared to do that.
Rondo agreed with Rivers' assessment that the team isn't necessarily in ideal shape, even if he said it's hard to gauge when he's on the court.
"You see it different from the sidelines," Rondo said. "But the coaches watch a lot of film and they know what's best. Today was a good practice."
The Celtics' woes are hardly limited to their conditioning. Rivers wants to get more from his second unit (which is why they practiced Sunday). The defense needs to tighten up (particularly the guards on dribble-drive penetration and the bigs on help rotations). And rebounding hurt the Celtics tremendously in Friday's loss.
Beyond conditioning, Rivers stressed that he wants to see more toughness.
"I think our chemistry is great. But listen, we can get along, but I want to win too," Rivers said. "Chemistry is phenomenal, I couldn't ask for a better group of guys. But I may be asking for a tougher group of guys. I'm not sure yet."
No amount of running will make his team tougher. But, hey, it's one thing off the "needs improvement" checklist.
Chris Forsberg covers the Celtics for ESPNBoston.com.