With the Vikings playing host to the Indianapolis Colts a couple of weeks ago on Sunday Night Football, veteran safety Harrison Smith used it as a chance to shoutout longtime trainer Charlie Petrone before a national audience.

“I’ve been around long enough,” Smith said. “I think most people know I went to Notre Dame.”

So in pregame introductions, instead of reciting his first name, last name and alma matter, the usual script during the player introductions that have become synonymous with Sunday Night Football over the past couple of decades, Smith decided to switch it up.

“Hitman,” Smith said while looking into the camera. “Petrone’s Wood Gym.”

It was a fleeting moment completely missed by anybody who wasn’t paying attention. That was kind of that point.

“That was for him,” Smith said with a laugh. “Not for anybody else.”

Nearly 1,000 miles away back in Smith’s hometown of Knoxville, Tenn., Petrone couldn’t believe his ears. He remembered the initial exchange from over the summer. He wrote it off as nothing more than talk at the time.

“He was like, ‘Dude, if I get a chance, I’m doing it,’ ” Petrone said. “I was like, ‘You’re not actually going to do it.’ “

The fact that he made good on his promise sheds some light on the brotherly bond Smith and Petrone have developed over the past 20 years. They started working out together long before Smith was drafted by the Vikings in 2012 and long before he went on to establish himself among the top players the franchise has ever seen.

As he reflected on his journey this week during an interview with the Pioneer Press, Smith credited Petrone with the longevity that has him on the precipice of the Pro Football Hall of Fame. He learned tools as a teenager working out in the Wood Gym that have helped him continue to play at a high level as a 35-year-old.

The simplicity of Petrone’s Wood Gym is its secret sauce.

The current facility is a 30-foot-wide by 175-foot-long wooden structure that prides itself on its minimalism. It is located off the beaten path on the outskirts of Knoxville and gets most of its business by word of mouth. There’s no air conditioning in the summer and no heat in the winter.

“It’s hot as (expletive) or cold as (expletive) based on the time of year,” Smith said. “That’s another charming aspect of it.”

There are dozens of jerseys lining the walls of the Wood Gym.

Some of the notable clients Petrone has trained in addition to Smith include former NFL offensive lineman Bruce Wilkerson, former NFL quarterback Chad Pennington and former MLB first baseman Todd Helton, among a long list of others.

“It’s not a program where everybody does the same stuff,” Petrone said. “I design a program specifically for each athlete.”

The initial encounter between Smith and Petrone can be traced back to former Vikings offensive lineman Tim Irwin. Talk about a small world. In the early 2000s, Irwin was coaching middle school football in Knoxville, and he recommended that Smith and a few other players start training with Petrone.

The group of teenagers started showing up at the Wood Gym with ulterior motives.

“He had this slushie machine at the time,” Smith said. “It was Sprite Remix flavor, and we would be in there trying to drink as many slushies as we could.”

The motivation changed as Smith slowly emerged as a rising star at Knoxville Catholic High School. He realized he had a chance to play in college and perhaps even at the highest level if he kept working at it.

“Honestly, from that point on, I worked out damn near every day,” Smith said. “I was in there as much as he would let me be in there.”

There’s a particular workout from his time at Knoxville Catholic that still sticks with Smith. He was running 300-yard shuttles in the Wood Gym and somebody jumped in to race him as he was finishing up.

“I was gassed and he was fresh,” Smith said. “He was ahead of me on the final turn and we were basically walking by the end of it. His legs gave out on the last 25-yard stretch and he collapsed. I walked to the finish.”

As soon as Smith was done, he grabbed his keys, hopped in his car and started the drive home.

“I threw up all over my windshield and I had to pull over,” Smith said. “You remember that type of stuff.”

A gravitational pull kept Smith coming back to the gym. It’s an indescribable feeling shared by everybody who walks through the doors of the Wood Gym. Even after he went away to Notre Dame, he would return any chance he got.

That helps explain why Smith chose to live in Petrone’s guest house ahead of the 2012 NFL Scouting Combine. He cut off contact with family and friends so he could focus on the task at hand. It was literally like a boxer sequestering himself in preparation for a title fight.

“That was something I’ll never forget,” Smith said. “Just going to work every day pretending like I wasn’t in my hometown.”

The decision shocked some people because of how highly rated Smith was coming out of Notre Dame. They were expecting him to go somewhere to train that had more bells and whistles. That simply is not how he’s wired.

“He was like, ‘Why would I go somewhere else when I know this works?’ ” Petrone said. “He never got caught up in having to do something different to get better.”

That mentality has followed Smith throughout his career with the Vikings. He knows his body better than most athletes. He has never strayed away from the Wood Gym as a result.

“It’s a pure place that’s not focused on the glitz and the glam,” longtime agent John McGeehan said. “That aligns with who Harrison is as a person and a player.”

There have been small changes over the years. They used to use metal boxes for plyometrics, for example, which forced everybody to be locked in.

“You didn’t want to miss or it’d be a serious problem,” Smith said. “We always say we like to have consequences in there.”

Nowadays, Smith and Petrone have more back and forth when figuring out a game plan.

“There have been times he calls me up like, ‘I’m not feeling it today. I’ll be there tomorrow,’ ” Petrone said. “Is it because he’s being lazy? Absolutely not. He’s just so in tune with his body and his mind. He knows exactly what he needs.”

It might not even be a workout at all.

“There’s a piece of it that’s almost like therapy,” Smith said. “Sometimes I’ll end up talking for hours and venting about life. Not only me. That’s how it is for everybody in there.”

That’s something former Vikings safety Andrew Sendejo recently got to experience for the first time. As close as Sendejo got to Smith during their time playing together, he never got a chance to work out with him in the Wood Gym until he booked a flight to Knoxville this past summer.

“We all sat down and we were shooting the (expletive) for like an hour before we even did anything,” Sendejo said. “It’s so obvious that they have a very close relationship. They almost have their own language in there. It was cool to see them create a workout in like 10 minutes and then go through it.”

The biggest reason Smith keeps coming back at this point is because it feels like home. He has spent so many countless hours in the Wood Gym in his life that it has become something he can count on regardless of circumstance.

“There’s a grittiness in there,” Smith said. “”If I’m working out on my own, I like to go back to where it all started.”

He recently returned to the Wood Gym while the Vikings were on their bye week. Though he easily could have asked Petrone to carve out some time to work with him personally, Smith showed up and worked out with everybody else.

“There are a lot of high schoolers that come through there,” Smith said. “I think when they see a guy come back and do the same workouts they’re doing, it’s meaningful for them. I also want to look good when I’m working out in front of them. I don’t want to let them down.”

There’s no retirement in Petrone’s future, with the 56-year-old joking that he’ll die in the Wood Gym. A hearty laugh faded into introspection as Petrone went down memory lane about the past 20 years working with Smith.

“I love talking about him,” Petrone said. “I’m getting chills right now because I know I’ll never get anybody like him again.”

Luckily for Petrone, Smith isn’t going anywhere. Whenever he hangs up the cleats for good, Hitman will keeping going to Petrone’s Wood Gym.

“Mostly to drink coffee,” Smith said. “Maybe I’ll do some abs.”