Altitude in football – how much of a difference does it make?

Though the debate surrounding altitude in football, and sport in general for that matter, has been around for a number of years, it was on April 1st 2009 that the debate was really thrown up into the air (the only pun in this piece, I promise) and into the public eye. On this date, Bolivia hosted Argentina in a World Cup qualifying match in La Paz, a city that lies approximately 3600 metres above sea level. The Bolivians came up with one of the biggest shock results in international footballing history, hammering nailed on qualifiers Argentina 6-1. The visitors looked uncharacteristically lethargic and were uncomfortable in possession. One can question the FIFA world rankings as much as they may please, but when the world number 6 ranked side at the time records a 6-1 loss to the ranked 58 side, many felt this was the final straw.

However, it was two years prior that FIFA first tried to address the issue of altitude in the game. In 2007, FIFA temporarily banned all international matches that were being played at above 2,500m. Less than a year later, after severe pressure from CONMEBOL (the South American footballing body) the ban was repealed. In a statement from 2008, FIFA claimed anything between 500m and 2000m was “low altitude”, and at low altitudes it was claimed “minor impairment of aerobic performance becomes detectable”. Beyond this, it is unclear where the figure of 2,500m being the acceptable limit was forged and why it was this particular altitude that was made the cut off limit. It is widely known that travelling to a higher altitude without the appropriate time to acclimatise has detrimental effects on cardiovascular activities (to the extent of mountain sickness, even below altitudes of 4000m), but beyond this, higher altitudes and the respective change in atmospheric pressure can result in significant change in the flight path of a football. The reason it took this long so address is relatively simple – many felt that altitude could just be part of a “home advantage”. The days of compact, dank away dressing rooms are well within memory and it is only in recent years that pitch sizes have been standardised in the English Premier League. The philosophy of complete neutrality, or in an economists terms “all other things being equal” is actually a relatively new idea – but nevertheless an idea that has to be addressed in the modern game.

Before delving into the studies, certain difficulties arise in data collection. Simply put, there are very few nations with any footballing integrity that also play at altitude. More specifically, most studies agree that there are just three. All based in South America, the majority of studies focus on matches at Quito, Ecuador (2800m), Bogota, Colombia (2550m) and La Paz, Bolivia (3600m). This small sample size of countries over this mythical 2500m boundary provides an obstacle in data collection, but luckily all three have long standing footballing traditions – meaning many matches have taken place at all three venues. Though there have been complaints at lower levels of altitude (Denmark and Netherlands blamed poor performance on playing at Johannesburg, 1750m), many studies have scrapped the idea that altitudes below 2000m have a large effect on performance. So for the sake of argument, we shall look only at the three nations in South America.

What is immediately interesting is that is appears there is no linear correlation in the data. It isn’t a case of ‘the higher you go, the harder it gets’ – but that only after certain altitudes does the game become much harder.

These graphs (taken from - http://economics.mit.edu/files/6572) show an interesting finding. The dark blue represents games below 2000m and the lighter grey above 2000m. It clearly shows that whilst Bolivia and Ecuador gain is almost all areas of the game from playing at home (3600m and 2800m respectively), the lower of the three national stadiums (in Colombia at 2550m) actually fared worse at home than when travelling. Furthermore, this data has been collected over many decades of play, so despite the small sample size of countries, the data for Colombia cannot be considered an anomaly. The analysis shows that travelling teams have success in Colombia, but just 250m further up in Ecuador the winning percentage from the home team increases by 25 to 30%. Further up in La Paz, the winning percentage increase becomes 45%. Perhaps this indicates that there should be a cut off for matches at altitude, but what remains unclear is how much of this advantage comes from the altitude change and how much from other factors traditionally associated with the ‘home advantage’. The variables that naturally differ from nation to nation (humidity, atmospheric pressure, air quality, temperature etc) certainly have to factor into this advantage too – and are equally difficult to control.

Interestingly, some studies have also made a connection between travelling to lower altitudes and this also having a detrimental effect on play. These studies, however, were conducted during the early part of the collective research into this subject, and failed to take into account footballing quality of the nations at higher altitudes and also the difference in quality of nations over time. Figures as erratic as a 27% less chance of winning when travelling to lower altitudes have been published – but fail to take in other basic variables. The most obvious outside variable is that the three most successful teams on the continent (Brazil, Uruguay and Argentina) all play at lower altitudes. If it wasn’t a complicated enough issue through battling the immeasurable variables and the limited data pool, it definitely becomes complicated once one has to sift through poor research. Any high school science or economics student will tell you that correlation does not equal causation. Reputed sports scientists working on data to be considered by FIFA, apparently, would not tell you this.

But beyond the poor quality of some studies, many are of course convincing and reputable in their argument – and it is said studies that provide some interesting findings. Initially, certain studies have claimed that whilst the outcome of the match does not change very often, the margin of winning does. World Cup Qualifying in South America currently uses a league table format, meaning that those findings are still significant. Furthermore, a different study into altitude speculates that more than a third of the goals scored in these three high altitude locations are scored in the final 15 minutes, and are overwhelmingly in favour of the home team. These two findings may well be linked, as this could show that visiting players are able to perform at close to their optimal level, but not for a full 90 minute match.

To conclude, whether anecdotal or statistical, no one can dispute the presence of evidence. However, at this time it remains unclear what specific altitudes should be deemed acceptable despite the apparent presence of a certain height where players can still perform. Thus, policy implementation becomes difficult. There is a clear advantage of playing in La Paz at 3600m, and this is almost universally accepted by the scientific community looking into this matter. But below this height, the statistics often contradict each other and a ban on a single nation’s participation in their national stadium would be widely protested. Furthermore, certain in game solutions have not been considered yet. Obviously acclimatisation is largely impractical due to the small time frame teams have to play international matches – but a system of a drinks break and short rest at the 22.5min/67.5min periods (as has been implemented in the French Ligue 1 to combat temperature issues) may well have a positive effect on the game’s outcome and standard over the full 90 minutes. This, at the present moment, is speculation on my behalf and has not been tested, but shows that the solutions don’t always have to involve an iron fist. What is clear is that this is an issue and a particularly complicated one at that; and whilst no decision will come without protest, but the data shows that something definitely should be done.

References and Sources:-

- Bartsch, Peter, Bengt Saltin, and Jiri Dvorak. 2008. “Consensus Statement on Playing Football at Dierent Altitude,f" Scandinavian Journal of Medicine & Science in Sports 18(Sup- plement 1): 96-99.

- Gore, C. J., P. E. McSharry, A. J. Hewitt, and P. U. Saunders. 2008. “Preparation for Football Competition at Moderate to High Altitude," Scandinavian Journal of Medicine & Science in Sports 18(Supplement 1): 85-95.

- Chumacero, Romulo A. 2009. “Altitude or Hot Air." Journal of Sports Economics 10(6): 619-638.

- Williams, Tyler & Walters, Christopher. “The effects of Altitude on Soccer Match Outcomes” 2011 (found at - http://economics.mit.edu/files/6572, highly recommended)

- http://www.rsssf.com/intland.html

- http://www.kingwoodcable.com/gpswaypoints/index.htm

- http://www.gpsvisualizer.com/elevation

- http://www.sportsscientists.com/2010/06/football-2010-impact-of-altitude.html

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