AIR FORCE ACADEMY, Colo. (AP) -- The tunnel leading down to the Falcon Stadium football field is dotted with warnings that a "lack of acclimation to altitudes above 6,000 feet has proven to cause serious illness."
Just before reaching the field, there's an overhang with a sign that warns about a "lack of oxygen " at 6,621 feet above sea level.
Meant more for intimidation than information, the signs still serve as a stark reminder of the Rocky Mountain's lung-piercing thin air. Which is exactly why Bill Belichick decided to keep his team in Colorado after the Patriots (7-2) destroyed the Broncos 41-16 Sunday night.
Up next for Tom Brady & Co. is a trip to Mexico City's Azteca Stadium (elevation 7,200 feet) to face the Oakland Raiders (4-5) on Sunday. So, rather than head home, the Patriots bused an hour south to train at altitude this week.
"You can feel it for sure," said tight end Rob Gronkowski, noting his skin was dry. "A lot of people are getting their nose super dry, their mouth super dry. So, I'm just glad to be here to prepare for what Mexico City will be, at the same altitude. So, it's good training and I'm glad we're doing it."
Belichick also brought his team to the Academy for its attitude.
They heard about survival training from cadets who had to hunt wildlife in the mountains; they listened to Falcons football coach Troy Calhoun talk about molding the next generation of military leaders; and they got to see paratroopers cap off Wednesday's workout on the Falcons practice fields.
"Which was super cool," Gronkowski said.
Belichick was first introduced to military and football formations as a youngster at the Naval Academy, where his father, Steve, had a 33-year run as a football coach and scout for the Midshipmen.
"I have a lot of respect for all the service academies -- but Navy first," Belichick said. "But a lot of respect here. These guys do a great job. … This is a great, great institution. The discipline, the leadership they have here. I hope some of it rubs off on me this week."
Gronkowski said this week has been a training camp-like bonding experience for the Patriots, who have toured some of the sites on the sprawling mountainous installation.
"It's good to have an understanding of where you are and what happens at an institution like the Air Force Academy," Belichick said. "We only have one guy that can really relate to that."
That's long snapper Joe Cardona, who attended the Naval Academy and knows firsthand the rigors of a military institution.
This week he's harkening back to his college days as the Patriots bond with one another.
"Being together as a team is great. You're surrounded by each other and it's great for building the team, and I can't think of a better way to do it than at the Air Force Academy," Cardona said. "Well, maybe at the Naval Academy. But it's great to be here."
Even in the thin air.
"I would be remiss to say I play enough plays to really have my lungs burning," Cardona said, "but there were a few times in practice that I had to breathe a little deeper, try to get the oxygen in."
Even though he knows all about the effects of altitude from his days as Denver's defensive coordinator, Raiders coach Jack Del Rio is taking the opposite approach. He's keeping his team at sea level this week just as he did last season in the lead-up to Oakland's game against Houston at Azteca Stadium, which the Raiders won 27-20.
"We're going in as late as possible, and they're spending the week training at altitude in Colorado," Del Rio said. "So, two contrasting approaches to it, and we'll see how it works out. We did this last year. We went the day before like we're doing this year and that seemed to work for us. I know that there are several theories out there in terms of how you best handle the altitude and we just do the best we can to prepare our squads, and then we go compete."
Tom Brady's usual Wednesday news conference was pushed back to Friday, but he's been looking forward to this Mexico trip since the Super Bowl.
"It will be a great experience for our team," Brady said when word got out last winter that the Patriots would head south of the border this year. "I've always enjoyed it. For our team, we've gone to London (twice), and I've loved those experiences. They've been great bonding trips for our team."
The Patriots played an exhibition game in Mexico City in 1998, beating Dallas 21-3.
"There's a lot of excitement down there, and they love football," Brady said. "We want to go down there and put on a great show."
The only college stadium that's higher than Falcon Field is Wyoming's War Memorial Stadium, which is 7,215 feet above sea level.
For one Patriots player, this is nothing, however.
Tackle Nate Solder grew up in Leadville, Colorado, which is 10,152 feet above sea level.
For more NFL coverage: http://www.pro32.ap.org and http://www.twitter.com/AP -- NFL
Follow Arnie Melendrez Stapleton on Twitter: http://twitter.com/arniestapleton