SANTA CLARA — Frank Gore’s fingernails are bitten down to their nubs, and he constantly fidgets with the cast that covers his right hand from the forearm to the knuckles.

The San Francisco 49ers’ Pro Bowl running back’s broken hand should be perfectly healed in time to begin defense of his NFC rushing title. That doesn’t make training camp any easier for a player who’s already had more than his share of injuries in his football life.

“I just feel awkward with this on my hand,” Gore said Wednesday, grimacing as he stood in front of his locker after missing another practice. “I’m still working, but it’s different without practice. I’ll be all right. I’m a football player, so I’ll be cool.”

Gore has been out of regular action since his hand got caught in a teammate’s pads during a blocking drill on the second day of training camp. Though he participates in conditioning drills and even takes handoffs on some occasions, the 49ers are keeping him away from contact.

San Francisco coach Mike Nolan doesn’t expect his franchise running back to play in the preseason until the final game in San Diego on Aug. 30, if at all. Though Gore is enthusiastic about his conditioning exercises, he’s obviously uncomfortable being on the sideline while his teammates prepare for a much-anticipated season.

“You know Frank is going crazy,” said Michael Robinson, who will be Gore’s backup along with Maurice Hicks. “He doesn’t like to be out of his uniform while the rest of us are playing. But he does a good job being a teammate and keeping up with what we’re doing.”

Gore got a hefty new contract in late March after his breakthrough season in 2006. The 5-foot-9 running back set a handful of franchise records while starting every game, posting new 49ers bests in yards rushing (1,695), total yards (2,180), carries (312) and single-game yards rushing (212).

Gore seemed most proud of his 312 rushes — a heavy workload for any back, but particularly large for a player who underwent reconstructive surgery on both knees in college, followed by major surgery on both shoulders after he led the 49ers in rushing as a rookie in 2005.

When he was completely healthy last season, Gore consumed playing time with the desperation of an oft-injured athlete who knows every snap might be his last. Gore only came out of games when he got winded, waving at running backs coach Bishop Harris for a replacement — and that didn’t happen often, with Robinson and Hicks combining for just 67 carries.

“I feel that the more I’m in, the better I get,” said Gore, who averaged 5.4 yards per carry last season. “If I’m switching up, I can’t get into a groove. I want to get in the game, and I’ve got to touch the ball 25, 30 times.”

Nolan won’t commit to a milder work schedule for Gore this season, but the coaching staff clearly would prefer to maximize Gore’s effectiveness by minimizing his exposure to hard hits. Nolan knows his star running back’s long-term health probably depends on it.

“If Frank has got to carry it 500 times for us to win a lot of games, he’ll carry it 500 times,” Nolan said. “If I can have him carry less and still win because of what the other guys have shown, we could do that, because then I’ll get Frank for maybe five or six years, rather than three or four, long-term.”

But don’t ask Gore to consider a lighter load. His fingers flinch in his cast at the very thought.

“I don’t see that. I don’t,” he said. “I’m not that type of back.”

There’s a bright side to all this inactivity: Gore should be fresh and injury-free when the 49ers open the regular season next month against Arizona, and he already has set a lofty goal. The day after last season ended, Gore announced his intention to rush for 2,200 yards in 2007, breaking Eric Dickerson’s NFL record of 2,105.

“As long as I’m playing, that (goal) will never change,” Gore said.