Philadelphia Eagles coach Chip Kelly did not make any allowances for the altitude on Thursday.
The Eagles are playing the Denver Broncos in the thinner air at Denver's Sports Authority Field at Mile High, which is located 5,280 feet above sea level. But Kelly did not change the Eagles' weekly routine.
"Football is an anearobic sport," Kelly said. "(Altitude) doesn't affect you the way you think. We're not going there to run a marathon. I think a lot of it is mental more than physical and it's not as big a deal as you think. We're at the same advantage or disadvantage of anybody else playing there.
"I think what really makes a difference when you play at altitude is who you play against. (The University of Oregon) played against the University of Colorado (in Boulder, Colo.) a couple of years ago and the altitude wasn't a big deal. But we're playing against the Broncos."
Some experts disagree.
Randy Wilber, a senior physiologist at the U.S. Olympic Committee's lab in Colorado Springs, Colo., and an expert in high-altitude performance, told the Baltimore Sun last year that "there are real physiological and therefore psychological advantages to the team that (is used to) playing at altitude. If the talent on the field is equal, I'd put my money on the team that plays in altitude."
Because the air is thinner, players are taking in less oxygen, so their bodies must produce more red blood cells to compensate. But the adjustment can take up to two weeks, so visiting NFL teams just have to deal with it as best they can.
The one thing the Eagles can do to help themselves is hydrate more than usual because the air is also very dry.
"That's definitely true," Eagles rookie tackle Lane Johnson said. "I've never played in Denver, but we (the University of Oklahoma) played in El Paso, Texas, against Stanford in the Sun Bowl and the elevation was something like 3,000 feet. It didn't affect me right away, but the longer we played, the harder it was to breathe. I also remember we had to drink a lot of fluids, even though we weren't sweating."
The Eagles are playing in Denver for the first time since the 2005 season, when they suffered a 49-21 loss in what turned out to be Terrell Owens' final game as an Eagle.
Only two current Eagles, linebacker Trent Cole and guard Todd Herremans, were on the team for that game. Both were rookies.
"I remember it was kind of hard to breathe a little bit," Cole said. "But we can't use that as an excuse. I'm sure we'll have oxygen tanks and things on the sideline. But no matter what, you still have to play as hard as you can for as long as you can. If you find yourself having trouble breathing, just tap yourself on your helmet and let the coaches know you need a breather, so to speak."
Quarterback Michael Vick recalled playing in Denver while with the Atlanta Falcons in 2004 and didn't think the rare air had any effect on him.
However, tight end James Casey and linebacker Connor Barwin both made two trips to Denver during their time with the Houston Texans and acknowledged that the altitude was a factor.
"It definitely takes some getting used to," Casey said. "But it wasn't like I couldn't breathe or anything. I think it will help me having played there before so I know what to expect. I don't think it will be an issue for me this time."
Barwin explained that the Eagles' defense can help itself by getting off the field as quickly as possible.
Fatigue and shortness of breath could set in if it allows Broncos quarterback Peyton Manning to extend drives and control the clock.
"You can't let yourself think about it too much when you're out there," Barwin said. "Besides, most plays only last four seconds, so we really don't have too much time to breathe anyway."
The Baltimore Ravens have played twice in Denver the last two seasons. In each case, Ravens coach John Harbaugh, a former Eagles special teams coach, had the team fly out there the day before the game.
They lost to the Broncos 49-27 in the season-opening game this year. Last season, they beat the Broncos 38-35 in overtime in the divisional round of the playoffs en route to winning the Super Bowl.
"The altitude is definitely an issue there," said Eagles cornerback Cary Williams, who played for the Ravens last season. "It's mental and physical. It's kind of a Catch-22. Your body's not used to it, but you still have to force yourself to go full speed on every play.
"Your will to compete has to overcome the physical stuff. You've just got to be mentally tough to deal with it."
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at Denver (3-0)
When: 4:25 p.m. Sunday
TV/radio: Fox/97.3, 94.1 FM
Line: Denver by 10