Since yesterday was only my third time in an NFL locker room after a game — only the second time after a game that counted — it still shocks me how normal everyone looks after running into each other for three-plus hours.

Was I imagining a scene with some players limping around on crutches and icing bruises, others lying on hospital cots and moaning like soldiers in a stereotypical military infirmary out of some movie? I’m not sure about that, but after games the 2012 San Francisco 49ers almost seem like they just concluded a non-contact practice.

Then again, teams in Candlestick Park’s other locker room probably feel a lot more pain. And the 49ers have yet to face a defense like their own.

Five games into the season, the 49ers are relatively injury-free and looking as energetic as ever. That includes Frank Gore, who looked healthy, happy and proud as he spoke with the media in a nearly empty locker room after rushing for 106 yards on 14 carries against the Buffalo Bills.

Gore focused on missed opportunities when asked about the offense’s record-setting day (probably due to his chop block that negated what would’ve been a 41-yard pass to Michael Crabtree), but otherwise he was nearly all smiles.

And why not?

The 49ers are better than they’ve ever been during his career, and Gore is still one of the best players in football. At an age when most running backs can no longer physically produce at a level that matches what they’ve learned over their careers, in some ways Gore is better than ever.

“I feel good. I feel fresh, young. I’m just out there having fun,” Gore said.

It’s not like Greg Roman and Jim Harbaugh are saving Gore for the playoffs, but they are using him slightly less than before. That includes last year.

The 49ers are using Gore less frequently than at any time since he became the full-time featured back in 2006. Gore only had 65 rushes through five games in 2009, but that’s because he only carried the ball once before leaving with an ankle injury in the third game of the season.

One area where the 49ers clearly need Gore less is in the passing game. That’s due in part to the bulk of the 49ers’ throws going to Michael Crabtree, Vernon Davis and Mario Manningham, along with the 49ers attempting the second-fewest passes in the league.

Meanwhile, the 49ers are No. 1 in the NFL in rushing yards (979) and yards per carry (an almost obscene 6.1). From Bill Barnwell of Grantland:

Last year, the 49ers’ rushing attack served as the inefficient bulk of their offense. Because they faced so many eight- and nine-man fronts, the 49ers ranked just 24th in rushing DVOA and averaged an underwhelming 4.1 yards per carry, which was 19th in the league. Frank Gore seemed a step slow at times, and, without a real deep threat to occupy defensive backs beyond the likes of Ted Ginn and Kyle Williams, the rushing game’s first and most important job was to avoid turnovers.

Things have changed in 2012. With a revitalized Gore and a more impressive Kendall Hunter running behind an improving offensive line, the rushing game’s gone from being a placeholder to becoming a legitimate weapon.

How is Gore revitalized at age 29, not quite two years removed from breaking his hip?

“My young guys, Kendall, Anthony Dixon, they’re keeping me young, just helping me keep going like this,” said Gore, who some thought would balk at the idea of ceding carries to his teammates. To the contrary, based on his comments after the 49ers routed the Bills.

“I wish ‘three-two’ could’ve gotten a hundred (yards). That would’ve been big. We had a great yards per carry. AD came in and finished them off.”

Besides the additions of Manningham and Randy Moss and improved play from Hunter, here’s Barnwell again on the other reasons why the 49ers’ run game is suddenly the envy of the NFL:

With Joe Staley and Mike Iupati, the Niners have the best left side of any offensive line in football, especially on the ground. Jim Harbaugh and offensive coordinator Greg Roman have continued to place an emphasis on personnel and formation diversity, further keeping defenses on their toes and creating mismatches. That’s only been heightened by the arrival of Colin Kaepernick and his Pistol playbook from Nevada, a dimension that the team was hesitant to bust out during Kaepernick’s rookie season. He’s been an effective runner so far, fumble on Sunday aside, and the Niners will undoubtedly create passing plays downfield for Kaepernick with those early-season runs as the year goes along.

As I detailed on Sunday, I asked Gore about how much easier the 49ers’ mobile quarterbacks — Kaepernick and Alex Smith combined for 88 yards on only seven carries on Sunday — have made things for the running backs.

“I love it. Especially last week, they sent Kaep on a reverse, and they got to respect it. Our o-line’s doing a great job up front. I’m just having fun just running the ball like a kid. Just jumping around, jump-cut here, jump-cut there, just go with it,” said Gore, clearly excited as he spoke.

It’s hard not to feel almost as good for Gore as he feels about the 49ers’ newly innovative offense, which he frequently referred to as “growing” after Sunday’s game. After years of losing and playing for teams that would repeatedly hand Gore the ball and task him with running through a brick wall, he can now pick and choose which defenders to jump around and which ones to run through — and he still has the youthful energy required to do both.