HOUSTON — Yao Ming's birthday wish: getting through an NBA season without getting hurt.

The 7-foot-6 center — who turned 28 on Sept. 12 — has missed more than 80 games across the last three seasons with four separate injuries. In 2005-06, he contracted an infection in his left big toe that required surgery, then broke his left foot later. In 2006-07, he broke his right leg. Last February, he broke his left foot in a different place, had surgery and sat out the playoffs.

Yao acknowledges that he has to change something, whether it's his workout routine or the number of minutes he logs in games.

"I need to learn something from the last three years. Seriously," Yao said after the Rockets' first practice on Tuesday. "Maybe I need to be careful with my pregame workout or something, lay down a little bit, not get my body too tired before a game. Let's try some new schedules, put my best shape into the game."

Coach Rick Adelman said he'll carefully monitor Yao's day-to-day schedule and hold him out of segments of practice to keep him fresh. Yao played 37 minutes per game last season and often resisted when Adelman tried to replace him.

"He's such a hard worker, he just runs himself into the ground," Adelman said. "He keeps saying he wants to rest, but he never wants to sit out. We're going to try to monitor him as much as we can, be smart in how we use him."

Yao was averaging 22 points and a career-high 10.8 rebounds when he sustained the stress fracture in his foot on Feb. 26. He recovered enough to play for China at the Olympics, but said his foot was only 70-80 percent healed.

His Houston teammates nervously watched his games in Beijing.

"You cringe because you don't want to see him fall down," said point guard Rafer Alston. "And then he falls, and things like that. Then, he's doing an interview, and he falls over a writer or a camera."

Yao averaged 19 points and 8.2 rebounds in Beijing, leading China to the quarterfinals.

"The Olympics was a very good tryout for me to prepare for the Rockets season," he said. "Some Chinese fans probably won't be happy, but that's just being honest. It feels great to come out of the injury. I had a good recovery. I feel fresh and ready for next season."

Houston assistant coach Jack Sikma made two trips to China — one before the Games and one after — to work individually with Yao. Sikma said Yao has lost about 10 pounds and just needs to regain his game conditioning.

The Rockets acquired Ron Artest and Brent Barry in the offseason and Adelman hopes that the improved versatility will give Yao more chances to rest — and fewer opportunities to get hurt.

Adelman is starting his second season in Houston and also has more confidence now in frontcourt players like Luis Scola, Carl Landry and Chuck Hayes, who can come off the bench to replace Yao. Dikembe Mutombo backed up Yao last season, but Mutombo has yet to sign a new contract.

"I'm very comfortable playing two of those guys together and that would help keep Yao's minutes down," Adelman said. "We had to play without him last year and those guys had to play, so I think having a versatility, we have some more things we can go to offensively."

Until then, Yao said he's not afraid to test his foot and go full-bore in practice to rebuild his stamina.

"The foot feels all right. I can't say it's like brand new, but it's like it's my foot," he said. "I can't wait to go, for the first preseason game, the first regular-season game."

Yao isn't the only Rockets player whose health worries Adelman.

Tracy McGrady said Monday that his left shoulder is arthritic and his left knee is healing slower than expected from surgery in the spring. Alston had surgery to repair ligaments in his right ankle and forward Shane Battier had surgery to remove bone spurs in his left ankle. Battier now has inflammation in his left foot that will keep him out at least four weeks.

"I never had a team where I had four starters have surgery," said Adelman, starting his 18th season as a head coach. "That's been one of my major concerns, how these guys are going to come to camp, where they are physically and how we are going to monitor that as we go through this first month."