GREEN BAY — At possibly the most collision-based of positions, one in which a player's willingness to hit can fade fast, fullback John Kuhn actually has become a more physical lead blocker even in his 30s.
The Dover High School graduate had fewer misses than ever before in the running game last season for the Green Bay Packers.
This summer, the sound of his pads cracking against linebackers in the fierce half-line drill has been a fascinating soundtrack of training camp.
The book on Kuhn since he arrived in Green Bay on waivers in September 2007 and began to play basically has remained the same. Personnel men around the NFC North admired his versatility and pass blocking but were lukewarm about his run blocking.
"He's not a hammer," one division scout said late in the 2011 season. "But he can get in the way."
Changing job description: Kuhn's job description before 2013 included far more than just lead blocking. The Packers' zone scheme didn't feature much downhill blocking by the fullback, and Kuhn also was a regular on the four core special teams.
"Back then, I played a lot of special teams and was leaner, thinner, faster," Kuhn said. "Now I play about two a game, and my roles on special teams are less-designed for open-field running."
When the Packers drafted big back Eddie Lacy a year ago and incorporated almost as many gap and power runs as zone, the 6-foot Kuhn gradually increased his career-long weight of 250 pounds to 255 at the end of last season.
He has been playing at about 257 this summer and, according to his coaches, has been thumping defenders like never before.
"That's been a huge emphasis for me the last year and a half," Kuhn said this week. "I'm not going to say I wanted to be the old-school fullback type, but it was more directed toward being able to knock guys out of the hole. I feel I have become a better blocker in recent years."
New coach in Gash: Sam Gash, the new running backs coach, made two Pro Bowls as a bone-crunching fullback from 1992-2003.
In his early discussions with Kuhn, Gash discovered a nine-year veteran open to many of his ideas, including striking with elbows down and tight before exploding upward into the defender almost like a bench press.
He also has seen that Kuhn still digs contact.
"I definitely feel like he's better," said Gash, who played his college ball at Penn State. "From what I saw, I think his desire to hit at the point is outstanding this year. John's different in the fact he's in great shape and has done a great job taking care of his body."
Offensive coordinator Tom Clements, who has watched Kuhn since his arrival, said there's no doubt his run blocking has picked up.
Adding weight: Over his career, Kuhn has been used as a fullback, an I-back, a one back and a third-down back. The Packers won the Super Bowl with him protecting Aaron Rodgers on third down.
Bright and adaptable, Kuhn has added weight and sculpted his body to fit a changing role.
"With explosive backs like Eddie, DuJuan (Harris) and James (Starks), they don't need too much space," said Kuhn. "Twelve to 18 inches takes a hole from here to there so they can make a big, big gain.
"We've gotten bigger and stronger to emphasize we do have a big, strong running back. The rest of our offense should emulate that type of running style.
"We still have the best quarterback in the NFL, and we are going to pass the ball a lot. If we're going to do 75 plays a game like Coach Mike (McCarthy) wants, there's going to be a lot of running as well.
"We want to be really good at the run this year."
Litmus test: The litmus test for a fullback always has been the isolation play in which he's slamming downhill into a linebacker who's charging to meet him in the hole.
Based on years of punishing head-on crashes, Kuhn divides linebackers into two categories.
"Some are just barreling down trying to take inches away from your side and you're barreling down trying to take inches away from their side," said Kuhn. "That's primarily where you put your shoulder into them.
"If you're going against a jump-around guy, more of a shaker, a guy who wants to give you less of his body, then it's hand placement. You have to make sure you sustain your block so you can't go barreling in with your shoulder because he'll make you miss."
Getting better: The Journal Sentinel has been tracking "bad" runs for more than 15 years. After having allowed an average of 4.2 in his first six years, Kuhn was judged to be responsible for only one last year.
"He's either going to stalemate or he's going to push the guy out of the hole," said Lacy. "It's very rare that you'll see him get hit and get pushed back in the hole.
"I couldn't line up and run into a linebacker every single play if they paid me $30 million. For as many years...and you still can go up and deliver that kind of blow, it says something about him and his competitive spirit."
Kuhn, who outlasted ex-teammates Korey Hall and Quinn Johnson at the position, mentioned former Packer Vonta Leach, Lorenzo Neal and Dan Kreider as lead-blocking fullbacks during the past decade that he respects.
"My whole career has been get your guy as best you can," said Kuhn. "When all else fails, hang on to your guy; don't let him make the tackle.
"Now Coach Sam has introduced some things where I can play more aggressive."
Lowering the boom: Julius Peppers, who outweighs Kuhn by about 30 pounds, has taken on blocks by him in practice and games.
"He lowers the boom," said Peppers. "Very powerful, very compact. Low center of gravity and he packs a punch."
Obviously, Kuhn has limitations in speed, athleticism and catching radius. The Packers also have become less reliant on two-back formations.
It's perfectly understandable that Kuhn's playing time has been greater in games 9-16 than in games 1-8 over the last three seasons. When the Wisconsin winter sets in, Kuhn's value increases.
In April, Kuhn re-signed for one year at $1.5 million less on average than he was making. Three weeks shy of his 32nd birthday, he understood.
He also is well aware of what scouts have said over the years about his less-than-robust style of run blocking.
"The first look somebody gets of you lasts," said Kuhn. "It'd be nice if I could change some of their minds."
Pro Bowl goal: In the last 20 years, nine fullbacks have been voted to more than one Pro Bowl. William Henderson (2004) and Kuhn (2011) were the only Packers. Kuhn really wants another.
"You get later in your career, you start talking about legacy and lasting impressions," said Kuhn. "I think multiple Pro Bowls says a lot."
"The fans are great. Fans appreciate the work I've done throughout my career. I'd like to play as long as I'm healthy and as long as they'll let me and I'm still having fun.
"I still love playing football."