Altitude and the World Cup

2010-06-21 00:00

I WAS just reading in a local paper that both Denmark and the Netherlands have blamed the altitude for their lacklustre performances in Johannes­burg.

The impact of altitude on football is not as clear as its impact on running and cycling.

First, South Africa is unique in that no other country I can think of demands that elite sportspeople perform at sea level and then at altitude with such regularity and with such short turnaround times.

Altitude affects performance in various ways. Broadly, there are two effects. One is on the physiology, which is my focus here. The second is on the flight of the ball — reduced air density means faster, further and higher, as any golfer will tell you.


Impact of altitude on repeat sprints

Reduced air density, although punishment for distance athletes, is a pleasure for sprinters. It is this factor that may be affecting at least part of the ball flight in the World Cup.

For football, the problem is that sprints are repeated over and over, with short recoveries. It’s therefore a hybrid of the two extremes. Altitude reduces sprint performance by between five percent and 10%, depending on the rest period.

When rest is longer (the 1:3 trial, with 45 seconds rest), performance is five percent worse

The concept of a pacing strategy for football is not one that has been thought about a great deal. It’s difficult to measure, for one thing. But I believe that the biggest impact made by acclimatisation is the improved ability to pace oneself. And the corollary is that teams that are not adapted will be compromised by this impaired ability to regulate effort over 90 minutes. The work:rest ratio has a crucial impact on performance. If the rest increases, the negative effect of altitude is negated.

So, in the World Cup, if teams play at a high intensity, with more off-the- ball movement, and more ball movement to force opposition into reduced rest periods, then the altitude is far more in play than if the tempo is reduced.


Fifa’s approach: What altitude?

These studies, plus my own experience of football, hockey and running, convince me that the altitudes of South Africa’s inland venues have a significant effect on performance.

So imagine my surprise when suddenly Fifa attempted to re-educate everyone that anything from 500 metres to 2 000 metres was now going to be defined as “low altitude”.

In other words, Fifa was saying: “The World Cup will not be at altitude, folks, but at low altitude, and so don’t worry about its effects.”

This is not made up — this is effectively what Fifa was saying with its “Consensus Statement”, published in the Scandinavian Journal of Medicine and Science in Sports in 2008. In addition, Fifa then attempted to stop scientists in South Africa from speaking about it. We were told that it was not an item for discussion.

I can only guess this is because Fifa wanted to downplay the impact of alti­tude, because it may detract from the tournament, and also because the selection of base camps by teams could not be biased by this “irrelevant factor”. The economic “punishment” imposed on the sea-level hopeful hosts would not be allowed.


Why altitude matters

At the elite level, a one-percent impairment in performance is significant. And we know (as shown above) that endurance performance falls off by 14% per 1 000 metres of altitude gain.

We know that a 1 500-metres difference produces a seven-percent impairment in repeat sprint performances. That’s not minor, it’s massive. But even if it were minor, it would be relevant to teams hoping to win a World Cup. The solution to this is to allow maximal physiological adaptation. It is no surprise to you to learn that all but a handful of the World Cup teams have chosen to base themselves at higher altitudes. They may miss out on the sea and mountains, but they control the physiology.


Will altitude affect what you see during the World Cup?

• Distance covered per player per match would be reduced. This would be due to two things. One is the decrease in the overall intensity of the game, because players would adjust their pacing strategy to conserve energy. Pacing in a team sport is complex, but I’ve no doubt it exists. The second is that I suspect that the game will slow down more than normal at altitude, as a result of increased levels of fatigue.

• Matches will fail to ignite in the second half, remaining low tempo. The drop-off in running distances (at various intensities — jogging, medium, high and sprint) will be greater between first and second halves. So matches will fail to come alive in the second half, and games will seem to be meandering along at a low tempo.

• Reduced number of sprints attempted per match. This is related to the pacing issue, but also, players will not recover between sprints. Shorter rests means worse performance per sprint. Therefore, at altitude, players will maximise recovery and sprint less, so that the performance per sprint will be maintained. A drop in the number of sprints has certain consequences.

— A reduction in the distance covered at high speeds. On average, players run 2,4 kilometres at high speed, and about 600 metres at sprint speeds. This would fall at altitude, primarily because fewer sprints would be attempted.

— Tactical changes would also occur because the ball flies faster at altitude. It will be more difficult to control, both for outfielders and goalkeepers.

— Therefore, ball-control skills will be affected.

— Players will shoot more from long distances. It has already been shown that at altitude, players tend to take more shots from further away. Is this coaching? I doubt it. I think players figure out very quickly that they can’t control the ball, and deduce that their chances are increased from further out.

Altitude turns great players into good players because it changes their activity profile in more or less the same direction as we see when comparing the highest level of football with a level below it.

Because the impact is the same for all teams (notwithstanding that a few teams have not based themselves at altitude), the overall dynamic of the game would not change too much. Which is why it’s unlikely to be decisive.

Something else to consider is that a football match is the result of so many factors, that isolating the impact of altitude is nearly impossible.


Altitude and the ball

In all these discussions on altitude, there is a huge effect that I haven’t covered yet — the impact of altitude on the flight of the ball.

The Jabulani ball has been slammed left, right and centre (unfortunately, it has not been slammed into the goal often enough) by coaches and players. Part of this may be the ball. It’s certainly different.

However, I really do believe that a big part of it is the effect of altitude on ball flight.

For example, a free kick struck from 30 metres out with spin, would be expected to curve a total distance of four metres when playing at sea level. At altitude, because the air density is reduced (in Johannesburg, on a cold night, it would be around 20% lower), the forces acting on the ball are different. The end result is that a ball will fly faster and further, and also deviate less than at sea level.

How much less? Some calculations show that the ball may move 60 centimetres less in Johannesburg than at sea level. It will also dip less, which is why it would be so much more difficult to get up and over the wall, but down in time for the goals. So when you see yet another free kick fly over by a metre, partly blame the altitude.

So consider a striker who tries to bend the ball around the wall and into the goals from a free kick — he misses by 50 centimetres to the right. That was a goal at sea level. At altitude, he blames the ball.

Meanwhile, the goalkeepers are complaining about the erratic movement of the ball, while strikers are complaining that the ball doesn’t move enough. Apart from the obvious contradiction of these complaints, I feel that the keepers are judging the reduced reaction time — a shot from 18 metres out will get to the goal about two ball diameters earlier in Johannesburg than in Cape Town.

That’s a significant distance, and it explains why keepers are floundering.  Their reaction times are 0,1% too slow. Tiny, but enough of a difference.

• Dr Ross Tucker has a Ph.D in exercise physiology from the University of Cape Town and a post-graduate degree in sports management from the UCT’s Faculty of Commerce.


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