GREEN BAY, Wis. -- Maybe you've seen the picture from Super Bowl I, when Kansas City Chiefs quarterback Len Dawson was photographed in full uniform, sitting on a chair in the locker room and taking a drag off a cigarette during halftime of the game against the Green Bay Packers.

Or perhaps you've heard the story of Packers defensive end Ezra Johnson scarfing down a hot dog on the sideline during a preseason game in 1980.

That is not the NFL that Chip Kelly and Mike McCarthy believe in.

"Not to say that stuff didn’t work," Packers outside linebacker Clay Matthews joked.

"There was a point where you'd smoke cigarettes and eat hot dogs at halftime," Clay Matthews said. "Now, we have specifically designed drinks for us and stuff that gets you up and going." Cary Edmondson/USA TODAY Sports

There has been much written of late about how Kelly, the Philadelphia Eagles' second-year coach, has brought an element of science to the NFL game. An ESPN the Magazine profile of Kelly by Seth Wickersham detailed how the Eagles players "wear mandated heart monitors and GPS devices. Trainers carry water bottles labeled with each player's name and after practice ask the players to pee into a cup, part of Kelly's plan to track hydration. A monitor on a wall in the facility ranks the most hydrated players. Drinking water is now a drinking game."

In a recent Grantland.com story, Chris B. Brown devoted a part of his Kelly profile to explaining how the Eagles take part in a full-speed practice the day before games "rather than the leisurely walk-throughs run by essentially every other team in the league."

If much of this sounds familiar, it's because in preparing for his ninth season as Packers coach, McCarthy has adopted some of the same practices in Green Bay.

This offseason, the Packers hired Catapult Sports, an Australian-based company that uses GPS technology to compile live data on athletic exertion and help determine how injuries can be prevented.

Nearly a month into training camp, and the Packers, who have been crushed by injuries in recent years, had just seven players who sat out of practice on Monday. Only one of them, defensive tackle Letroy Guion, had a muscle pull.

"I don't want to really talk about it, honestly," McCarthy said Monday of the relatively low injury totals. "We have a lot of football left."

McCarthy also altered his weekly routine that will put the players through a practice the day before a game. Previously, all of the Packers' on-field work was completed about 48 hours before kickoff.

"Here we are now getting it going on Saturday," Matthews said. "It's a fast, crisp practice. The next thing you know [the game is] the following day. So it doesn't feel like there's a lull. It doesn't feel like there's a wait until the game. You just kind of roll right into it."

And then this summer, the Packers hired nutritionist Adam Korzun, who previously worked at the University of Oregon, where it just so happens Kelly coached before jumping to the NFL in 2013. Korzun has been working closely with strength and conditioning coach Mark Lovat.

"These are … discussions that have been going on for some time," McCarthy said when asked about the comparisons to Kelly's program. "Mark Lovat does a great job staying on the front end of the research and the stuff that's out there. We've done a pretty good job around here training our players and winning games.

"We're about winning championships. Anything we feel we can do better, we're going to do our due diligence, go through it. Never want to just do something because someone else did it. But if they're doing something that's better than what we're doing, then we're going to do it. This is the Green Bay Packers. We have tremendous resources and our organization gives us that each and every year, and we feel the changes we made have been for the best."

Matthews' younger brother Casey is a linebacker for the Eagles, but he said the two have not spent much time discussing the similarities of their respective team’s use of sports science. Clay Matthews said he has done some reading about what the Eagles are doing, and it sounds a lot like what's going in Green Bay. Matthews said the Packers are monitoring players' hydration levels by checking urine samples on a regular basis just like the Eagles do.

"Seeing this change, I'm able to buy into it," Matthews said. "And I think the other players are too just because of the science behind it."

Receiver Randall Cobb, who said he has changed his eating habits and has not eaten red meat in three months, said the team has done sleep studies to give players more information about their health and conditioning.

"Now it's on us as pros to go out and do those things," Cobb said. "They're giving us the education and helping us understand that what we can be doing to help ourselves."

This is not the NFL of Dawson and Johnson, of halftime smoke breaks and sideline sausages.

"I just think it's the natural progression of the league," Matthews said. "There was a point where you'd smoke cigarettes and eat hot dogs at halftime. Now, we have specifically designed drinks for us and stuff that gets you up and going."