# Does an NFL placekicker have better distance at Invesco Field in Denver?September 29, 2009 6:56 AM   Subscribe

NFL/science question: From time to time a sportscaster or writer comments on an NFL kicker's success in the "high elevation" of Denver's Invesco Field. I understand that there's less air pressure when you're a mile above sea level, but does this really have an appreciable effect on a 55-yard field goal attempt?
posted by jackypaper to Science & Nature (23 answers total) 1 user marked this as a favorite

I believe the 'common sense' reasoning behind this is that the air is 'thinner', thus providing less resistance to the ball.
posted by spicynuts at 6:59 AM on September 29, 2009

Not football, but a little googling turned up this study that shows that balls at Coors Field in Denver travel farther than at other ballparks.
posted by Hello, Revelers! I am Captain Lavender! at 7:09 AM on September 29, 2009

Commentators were talking about Usain Bolt running faster at higher altitudes. Shaves hundredths of a second. So yes.
posted by weapons-grade pandemonium at 7:13 AM on September 29, 2009

Aren't they talking about aerobic athleticism in the less oxygen-rich air?
posted by orthogonality at 7:17 AM on September 29, 2009

This page claims baseballs travel 3-7% further in Denver, and that field goals are attempted 5-7 yards further than they would be otherwise.

Part of this is air pressure, no doubt, but I'd guess that part of it's psychological as well. Because there's this meme that field goals can be kicked further, kickers (and coaches) will approach long attempts in a more positive frame of mind, with - I would guess, given the amounts of money sports psychologists are paid - appreciable results.
posted by momentofmagnus at 7:17 AM on September 29, 2009

Best answer: At the same time, this regression study claims that altitude does not actually have an appreciable impact. The probability formula for kick success is logit(pi) = 4.4984 − 0.0807distance + 1.2592PAT − 0.3306change + 2.8778wind − 0.0907distance×wind...
posted by momentofmagnus at 7:20 AM on September 29, 2009 [3 favorites]

I tend to doubt the thin air theory since air is useful to aid the trajectory and lift of the spinning ball. Whether it be a baseball, football or golfball.
posted by Gungho at 7:23 AM on September 29, 2009

Aren't they talking about aerobic athleticism in the less oxygen-rich air?
posted by orthogonality

No. It's that the thinner air provides less resistance. I believe long distances would be more difficult because of the reduced oxygen, but sprints are easier.

From eHow:
Appreciate the fact that exertion at high altitude is more difficult than at sea level. This is so because of the reduced partial pressure of oxygen as elevation rises. The decrease in oxygen pressure impairs the oxygenation of blood flowing through your lungs, ultimately resulting in a corresponding diminished oxygen supply to working muscles. Studies by the Federation of Sport at Altitude have shown that the lack of oxygen at elevations above 10,000 feet translates to 25-40% less muscle power.

From Wikipedia:
Furthermore, sprint athletes perform better at high altitudes because of the thinner air, which provides less air resistance. In theory, the thinner air would also make breathing slightly more difficult (due to the partial pressure of oxygen being lower), but this difference is negligible for sprint distances where all the oxygen needed for the short dash is already in the muscles and bloodstream when the race starts. While there are no limitations on altitude, performances made at altitudes greater than 1000 m above sea level are marked with an "A".
posted by weapons-grade pandemonium at 7:28 AM on September 29, 2009

Look at home run statistics in Coors Field. Eyepopping numbers of balls get hit out of that park. It is attributed to the altitude with statistical signifiance.
posted by stratastar at 7:29 AM on September 29, 2009

Bob Beamon's Mexico City long jump is another commonly-cited example of this phenomenon.
posted by box at 7:30 AM on September 29, 2009

At higher elevation, with less oxygen, any athletic task is much more difficult. I would be quite surprised if air resistance were a big factor.
posted by Mom at 7:35 AM on September 29, 2009

Look at home run statistics in Coors Field. Eyepopping numbers of balls get hit out of that park. It is attributed to the altitude with statistical signifiance.

Another issue was that the lack of humidity made the balls there more dry than the ones in other cities, which made it harder for pitchers to get a good grip and throw good breaking pitches. Since 2002 they have kept the balls in a climate-controlled humidor, which many say has been the main factor in reducing the number of homeruns hit in their ballpark in recent years.
posted by burnmp3s at 7:36 AM on September 29, 2009

Look at home run statistics in Coors Field. Eyepopping numbers of balls get hit out of that park. It is attributed to the altitude with statistical signifiance.

Todd Helton has hit 199 home runs at Coors field, and 125 away. Is this 74 home run difference statistically significant?

Barry Bonds, who has played his entire career in the National Leauge, as well, has not hit the majority of his homeruns at Coors Field.
posted by dfriedman at 7:39 AM on September 29, 2009

Veering slightly off-topic: Coors Field (Denver) is definitely a hitter's park, and there are certainly plenty of articles alleging that the thin air plays a big role in that. But it's not just that the ball goes farther when hit -- you also have to think about the effect of the air on pitches (e.g., breaking balls break less), and about how the super-gigantic outfield turns lots of would-be pop-ups into base hits. See, e.g., this article, which admittedly just basically states these same things without proof.

I'll have to think about your actual question. Offhand, though, I would think that the altitude would indeed have a noticeable effect. The aerodynamic drag on the ball is proportional to the density of the air, and the density of the air in Denver is only around 80% of the density at sea level.
posted by chalkbored at 8:15 AM on September 29, 2009

A quick search later, I found this nice analysis of the flight of a baseball at altitude, by a physics prof at UIUC. Much of the same stuff should apply to the football case.
posted by chalkbored at 8:22 AM on September 29, 2009

burnmp3s: "Look at home run statistics in Coors Field. Eyepopping numbers of balls get hit out of that park. It is attributed to the altitude with statistical signifiance.
"

My father works for the Colorado Rockies organization and I have been in the humidor where they store all of the baseballs. The baseballs in the humidor feel completely different than the ones they leave out for batting practice. The non-humidor baseball's dry out and get very slick (imagine highly polished leather shoes) You honestly feel like you don't have a good grip.

Part of the thought process on this changing home runs is that the pitchers couldn't throw some of their control pitches and were basically throwing balls that an 8th grader could hit. Throw a sinker that doesn't sink, or a slider that doesn't slide and see what happens. Serving up a 70 mph shit nugget is going to allow more home runs to be hit. Of course this is all purely anecdotal on my part, but there is a large difference in the appearance and feel of the baseballs.

So in closing, yes the altitude has something to do with, but it's a combination of circumstances that allowed for Coors field being the purgatory of professional pitchers for many years. As for the kickers getting more yardage in football, I don't really know. :) I played soccer for years and years and I would like to think that I could kick the shit out of the ball because I was just that good. :)
posted by Gravitus at 8:31 AM on September 29, 2009 [1 favorite]

I think the announcers just got used to Jason Elam kicking really long field goals. (He's tied for longest ever, which was done in Denver).

However you won't be able to get good data out of Elam, because he spent the bulk of his career with the Broncos; and even if he has kicked longer in Denver than games played elsewhere, that could be due to home field effects more than altitude. And if now at Atlanta he kicks fewer long goals, well that might have to do with being past his prime.

The Helton/Bonds comparison doesn't work, though, because Helton has played half his games in CO as he was actually on the Rockies.
posted by nat at 8:33 AM on September 29, 2009

Marginally off-topic: track races under 800 meters (and field events) are aided by thinner air. Anything longer is slowed down by reduced oxygen uptake. Case in point: 1968 Olympics in Mexico City.
posted by djb at 8:46 AM on September 29, 2009

At higher elevation, with less oxygen, any athletic task is much more difficult.

This is true for aerobic tasks. Kicking a football and hitting a baseball are anaerobic. The lower air pressure is significant enough to increase the distance by a few percentage points.
posted by rocket88 at 8:53 AM on September 29, 2009

Todd Helton has hit 199 home runs at Coors field, and 125 away. Is this 74 home run difference statistically significant?

Yes, it would be statistically significant, but there are many variables besides elevation to consider. For example, players nearly always hit more home runs at home, and baseball parks vary in dimensions. It could very well be that the 74 homer difference says more about giant ballparks in the rest of the National League. Moreover, the Rockies were a recent expansion team, which meant that during their first years in business, they had a poor farm system and were thin, talent-wise, in the pitching position.

There are also steroids to consider. The Rockies were founded in 1993, right at the cusp of the Steroid Era. I'm looking at you, Dante Bichette.

But there's plenty of evidence, anecdotal and data-driven, to suggest that Coors Field is (or used to be) where pitchers go to die.

Barry Bonds, who has played his entire career in the National Leauge, as well, has not hit the majority of his homeruns at Coors Field.

That is to be expected. Bonds played literally half of his games in Pittsburgh and San Francisco.
posted by Cool Papa Bell at 10:13 AM on September 29, 2009 [2 favorites]

Well, if it changes how cakes rise, why wouldn't it change how footballs fly? Pressure at sea level is 14.7 PSI, in Denver it is 12.1.

I don't think a football is affected nearly as much as a baseball or a golfball, as far as the spin+air= go farther vortex effect goes. I think a football is much more just plain old drag. And less air means less drag.
posted by gjc at 5:27 PM on September 29, 2009

Hey, nobody has mentioned gravity! At 5,000 feet elevation, you are farther from the center of the earth, and the force of gravity is slightly less than sea level. So any ball thrown or kicked goes farther before gravity pulls it back to the ground. The change in gravity isn't a lot, nothing you'd notice jumping up and down, but is enough to change how far the ball goes.
posted by exphysicist345 at 7:09 PM on September 29, 2009

Time of flight, assuming a spherical earth (and cow while we're at it) and no air resistance or difference-in-ball (e.g. humidity) or difference in kicker/hitter effects:

time at mile high = time at sea level *(1.0005).

Since we're assuming the same kick, or hit, I don't think a difference that tiny matters.

(for the non physics folk: why? because earth is 4000 miles in radius. 1 extra mile just doesn't make a huge difference in how big 1/radius^2 is.)

Since you're an exphysicist I'll assume you were being silly on purpose (and you can assume the above is included for pedantic purposes), and mention that if we're going to that level of precision clearly we should be considering the effect of time dilation due to being at higher elevation. It might actually be more relevant to consider temperature (as it affects ball characteristics, players, and air density), and I'd be pretty surprised if there isn't a noticeable precipitation effect. Hard to measure on baseball players though because they get wimpy and go inside when it rains.

Oh and in light of the article chalkbored linked to, does anyone know what happens to a humid football vs. a dry one?
posted by nat at 11:07 PM on September 29, 2009

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