Major League Soccer in Utah is one-of-a-kind, unique not only in the tenacity of its fans and richness of the Club’s two-decade, one-generation culture, but also unique in its climate. Nestled along the striking beauty of the Wasatch Front, less than an hour from eight or so world-class ski areas, America First Field provides a different sporting environment that you’ll find anywhere else, but what makes it so special?
To answer this question ahead of Saturday’s home Rocky Mountain Cup rivalry match - Leg Two of the season series - with the Colorado Rapids, another side that competes at elevation, we need to understand how variables like elevation, temperature, air pressure and wind interact with both the human body and the soccer ball. So, let’s put on our Claret-and-Cobalt lab coats and get into the science!
A scientist would say that the quantity of air molecules in the atmosphere decreases as height increases, and that these tiny air molecules are constantly moving and colliding with other objects, exerting a force - this force exerted is called air pressure. However, you are probably not a scientist, so for the purposes of soccer science, it’s helpful to think about the principles of air pressure in more simplistic, analogous terms that we’ll use later in connection to the international game. One way to imagine the first core principle of air pressure is to compare it with the water in a pool.
Near the surface, the weight of the water on your body is relatively light and we can withstand these forces without any issue. Then, as we dive deeper and deeper into the deep end of the pool, the weight of the water, in other words the pressure, increases and projects uncomfortable forces on the human body. Your ears pop, your sinuses scream out for help, it’s immediately obvious that your body is under pressure. In the pool, the pressure becomes lighter the higher you go from the bottom, as less water is around you, until you eventually emerge from the water and it stops exerting force on your body altogether.
In the same way, if we start on the surface of the earth and we keep ascending all the way through each layer of our atmosphere, the air molecules become fewer and farther between, pushing on the objects in the atmosphere less and less forcefully. As the elevation rises, the quantity of air molecules will continue to decrease until they cease to be there at all, at which point there is no air left to exert any pressure… because you have left the atmosphere.
The average barometric air pressure, or atmospheric pressure, at sea level is 14.7 PSI, or pounds per square inch. If we change the scale, we can simplify the idea by visualizing an everyday object, like a three-foot-by-three-foot table, instead of thinking in per-inch proportions. At sea level, this table has 19,051 pounds of pressure being exerted on it by the atmosphere. Yes, it seems impossible and absurd that a regular table could have more force acting on it at all times than the weight of some cruise ship anchors or even a pair of elephants. So how is that possible, how are we not smashed into the ground by this weight, how are we not crushed? Importantly, just like with water in a pool, air pressure is exerted equally in all directions. The same amount of pressure that pushes down on you also pushes up on you and equally in every other direction at all times, and every living thing withstands this pressure.
So what does this have to do with Real Salt Lake?
Let’s use the most-recent sold-out Rocky Mountain Cup rivalry match with Colorado as the example. America First Field, home to the best fans in MLS, sits about 4,450 feet (approx. 1,350m) above sea level, and on that March 9 day it was around 45 degrees fahrenheit when the match kicked off at 7:30 p.m. We can plug these numbers into the barometric formula to calculate that the air pressure at AFF was around 12.4 PSI. This means that for that early-season Saturday’s match, the air was exerting around 12.4 pounds of pressure on every square inch of surface. On the same night, kicking off at the same time, more than 3,000 miles away, Orlando City FC faced off against Minnesota FC at its home stadium in Florida - but was their air so different from that in Utah?
Let’s take these same figures to calculate what the air was like in Orlando - Inter and Co. Stadium in Orlando sits around 75 feet above sea level and the air that night was around 78 degrees fahrenheit. When we calculate these two pieces of information, plus a few other complicated numbers like the air pressure constant at sea level, the universal gas constant and the gravitational acceleration of the earth, (don’t worry there are free and simple calculators online that will do it for you) into the barometric formula, we find that the air pressure for the match in Orlando was around 14.7 PSI. When we compare this to the 12.4 PSI reading that we calculated for Real Salt Lake’s match, a 2.3 PSI gap between the two measurements appears. This 2.3-pound gap between Orlando’s air and ours here in Utah means that the air at America First Field was 15.6% lighter than the air across the country on the same night.
This difference in the pressures exerted by air affects everything, impacting every element of the game on and off the pitch. So how does the air pressure affect an MLS soccer ball during a match?
When thinking about how a soccer ball interacts with the air as it flies towards the net for an RSL goal, the important ideas are drag/resistance and lift - both are directly correlated with air pressure. When a ball flies through the air, the distance it travels depends primarily on the lift it achieves and the resistance it faces. Now that we know the air for Saturday night’s matches was 15.6% lighter at America First Field than in Orlando, we can apply this in practical terms. First, because the air is ‘thinner’, balls achieve easier lift and fly further than they would at sea level. This is because as air moves faster, pressure decreases - so the pressure on top of the ball is less than the pressure on the bottom of the ball, allowing it to fend off the forces of gravity and fly further (achieving and maintaining lift).
Second, this change in air pressure affects how the ball acts in flight. Everybody loves when one of their favorite players like Chicho Arango or Diego Luna curls one around the goalkeeper with wicked spin, seemingly making the ball turn. World-class players are able to do this because, sometimes without them knowing it, they’ve mastered an understanding of how their ball interacts with the laws of physics and the forces of our atmosphere.
When a ball flies at normal speeds, it parts the stream and forms even layers of air around each side of the ball - this is called laminar flow. When this occurs, air sticks to the ball - this is drag. However, when a ball is kicked with power and spin, this phenomenon is disrupted. When we increase the speed that the ball flies through the air, the velocity reaches a tipping point where the laminar flow stops and turbulence takes over. When this laminar flow is cut off, drag is dramatically reduced for a short time and it rockets through the air until it slows slightly and ‘catches’ the air again, suddenly sticking to the ball again and changing its direction (curve).
Players put spin on the ball to one, achieve this effect easier, and two, to specify the direction of their curve. As spin is applied to the ball, just as with distance, the pressure decreases on the side of the ball with faster air - so as turbulence subsides and drag catches the ball, the displacement of pressure on one side of the ball will guide it into the direction of rotation. So if two players took the exact same shot on Friday night, one at America First Field and one in Florida, physics would say the ball kicked in Utah will curve less and fly further than the ball in Orlando
When asked about how RSL athletes interact with the physics of their air, Real Salt Lake Director of Sports Science Johnny Fabrizius confirmed that it plays a part in the game.
“Understanding how [the air] affects the ball is a big piece of hand-eye and hand-foot coordination, being able to predict landing and trajectory. It becomes slightly more difficult when conditions change. It’s minimal, but some athletes thrive in tracking flight paths of the ball … it becomes even more difficult to adapt. One percentage point off in judgment can make a drastic change in the mind of the athlete - if I’m one percent off on my touch, the ball can go another six inches, and that can be the difference in any game in Major League Soccer.”
Air pressure impacts the flight of the ball, and the players have to adjust, but how does the change in environment affect the players themselves?
It is generally accepted that the effects of air pressure and elevation begin to measurably impact the ability of humans to output energy, or perform work, at around 500 meters of elevation and grows in the intensity of its consequences as altitude climbs. With this climb, air becomes thinner and the partial pressure of oxygen is decreased. With the pressure of oxygen decreased, oxygen intake reduces and limits the maximum aerobic power of the athlete. In other words, the reduced oxygen intake limits the efficiency of the “work” the body is performing, thus increasing the intensity/effort required to achieve results. This also affects athletes by delaying their ability to recover high-energy phosphates between periods of vigorous effort.
Work becomes harder for the athletes at elevation because their body is being fueled less efficiently than it would be in normal conditions, and the experts say this variance in bodily efficiency caused by changes in elevation are even more dramatic for professional athletes than the every-day person in a typical environment.
So how do the athletes fight back against the limits air pressure is trying to put on them? Through acclimatization. The research shows that athletes’ ability to re-regulate their senses, bodily processes and coordination is most substantially achieved by simply adapting to the change in atmosphere over time. After a short but not insubstantial period of time, athletes are able to reach a balance with the environment and overcome the body’s reaction of increased heart rate, cardiac output, blood pressure and other compensations to achieve a level of normalcy. It is crucial in this period of acclimatization that sleep, hydration, nutrition and energy conservation are prioritized.
When asked about his insights into acclimatizing to soccer along the Wasatch Front, Fabrizius says:
“We largely monitor the integrated physiological markers of the body like energy recovery and metabolic rate. It all depends on the development of energy pathways to get optimal performance. At high elevation, it becomes more challenging for the body to use its metabolic processes. For example, Matt Crooks for the first four to five days, it’s difficult to adapt. We do heart-rate recovery testing to show how the body is intaking and using oxygen. The first week he did the test, he had a relatively low score for his quality of athlete, but showed a massive improvement the second time around after he could acclimate.”
So the unique Utah air affects the play and players, but does it really have an impact on the outcome of matches? Any RSL fan would tell you that The Riot is what makes America First Field a fortress, but the research suggests our home being nestled where it is likely contributes to so-called ‘home-field advantage’. Studies have demonstrated that teams based in high elevations not only have a statistically significant advantage in terms of achieving positive results in their home environments, but that they also perform better when playing on the road at low altitude. The findings suggest that the metabolic resiliency of teams based at elevation, and the toughness their regular training/playing conditions cultivate, carries over to dominant performance in all atmospheric conditions - and with Colorado being the only other MLS team based at comparable elevation, the rivalry is as even as the playing field gets.
So now to Saturday, the second leg of a Rocky Mountain Cup series that’s not just a meeting of our League’s fiercest rivals, but also a meeting of our League’s two most altitude-adjusted sides, with RSL looking to avenge a first-leg defeat. In that fateful March 9 encounter with Colorado, it was a late first-half penalty call that seemed to rattle RSL’s mentality and lead to a disjointed second-half performance, as cited by numerous players and coaches as the team’s least cohesive half of the year.
Ultimately, RSL lost that match, 1-2, wasting Emeka Eneli’s first-ever professional goal and a solid performance by teenage goalkeeper Gavin Beavers. That Rapids win was the Colorado club’s first on Utah soil since 2020, and its first on Utah soil with fans in the stands since 2007 - SEVENTEEN years prior!
All time, RSL and Colorado have played 60 games across all competitions – 57 in MLS play and three in the Lamar Hunt U.S. Open Cup. Overall, RSL has won 30, lost 18 and tied 13 matches against Pablo Mastroeni’s former side, outscoring the Rapids by 31 goals overall.
The teams’ first-ever meeting was also RSL’s inaugural home game, famously won 1-0 on a Brian Dunseth header in a game that also included Mastroeni, Kyle Beckerman, Nat Borchers, Clint Mathis and several others who have worn both the Claret-and-Cobalt and the Burgundy-and-Blue.
The altitudinal factors described above have not provided a material advantage to either side, RSL dominant on the Wasatch Front, with 17 wins, six losses and seven draws, winning 14 Rocky Mountain Cups in the last 19 years. In suburban Denver, RSL has won 11 games, lost 12 and drawn six, with RSL winning the lone neutral-site match played during the pandemic bubble in 2020, a 2-0 victory in Orlando.
To become a part of our home-field advantage and get your tickets to Major League Soccer’s fiercest rivalry at America First Field this Saturday, May 18, visit rsl.com/tickets
