Grasping at thin air

I was contacted earlier today by IBWM’s resident boffin, Liddletowers, who wanted to draw my attention to something he’d read in New Scientist..........and when did you last hear Jim White say that on Sky eh? We have a resident boffin, see the calibre of what you are dealing with here Football365? 

Now I’m not stupid, despite a fairly comprehensive charge sheet, but advanced science to IBWM usually starts and ends with Johnny Ball.  However this little bit of physics relates to football, so I’m duty bound to take notice.

Yes, that's us

Now rather than try and pick out selected quotes, IBWM has took the easy option and just copied and pasted large chunks of text, which goes against the grain, but it’s actually one of the most interesting pieces I’ve read this year.  Get this:

FEBRUARY 2007. Brazilian football team Flamengo are playing a South American cup match in Bolivia. Their opponents, Real Potosi, are based in the high Andes and the stadium is nearly 4000 metres above sea level. In lashing rain, Flamengo fall 2-0 behind. Many of their players need bottled oxygen to alleviate the effects of altitude. Though they eventually fight back for a 2-2 draw, Flamengo announce after the game that they will no longer play matches at altitude. 

So began football's "high altitude controversy". Flamengo's case was taken up by the Brazilian Football Confederation, which complained to the world governing body FIFA that venues in the high Andes were not suitable for football. In May 2007, FIFA ruled that "in the interests of player health", international matches could no longer be played above 2500 metres. 

If Brazil thought that meant victory, they were not reckoning on a comeback by Bolivia, Ecuador and Colombia, who complained to FIFA that this would put a stop to international matches in their national stadiums. In response, FIFA suspended the ban pending further studies. 

Fast-forward to June 2010 and altitude is again an issue in football. The World Cup in South Africa will be the first for 24 years to stage games at venues significantly above sea level. The main stadium, Soccer City in Johannesburg, is at 1701 metres. That's not quite the high Andes, but it is still high enough to have an effect. Six other venues are at altitude.

FIFA invited leading medical scientists to a conference in its home city of Zurich, Switzerland, in October 2007 to discuss what was known about the effects of altitude on football. 

The first thing they looked at was physical performance. They concluded that below 500 metres there are no effects. Above 500 metres, negative effects such as increased heart rate, breathlessness and reduced stamina become noticeable and get progressively worse the higher you go.

The standard way of minimising this decline in performance is a few days of acclimatisation. The FIFA team recommends spending three to five days at altitude, although it is never possible to recover full sea-level fitness levels in this way.

There is, however, a wild card. Some researchers at the meeting noted that there are reports of athletes who are acclimatised to altitude suffering a decline in performance after suddenly descending to sea level. 

This effect may put them at a corresponding disadvantage when they come down to play a team acclimatised to sea level.  This could influence the latter stages of the tournament, as both semi-finals will be played at sea level between a team that won its quarter final at altitude and a team that won at sea level. 

It's not just physical performance that is affected. The FIFA team also concluded that altitude is likely to alter the aerodynamics of the ball in a way that could catch players out.

The key to this is the reduced density of the atmosphere, which affects how fast the ball moves through the air and also the bend of a spinning ball. Every 1000 metres increase in altitude reduces atmospheric pressure - and hence the density of the air - by about 11 per cent.  Other things being equal, Johannesburg has an atmospheric pressure around 81 per cent that of Cape Town. 

Temperature also has an effect, with air density falling 3 per cent for every 10° C rise. So the difference in air density during a chilly winter evening in Cape Town (7° C) and a relatively balmy winter afternoon in Johannesburg (11° C) could be over 20 per cent. Such differences are quite possible during the World Cup. 

To see what this difference would mean in practice, consider a ball struck from just outside the penalty area - and aimed at the top left-hand corner of the goal. Say that at sea level, the shot travels at an average speed of 22.8 metres per second and crosses the goal line after 0.817 seconds 

What happens at higher altitude? Since drag force is proportional to air density, an identical shot at 1700 metres travels faster than at sea level, reaching the goal line after 0.801 seconds - about 2 ball diameters ahead of where it would be at sea level. This gives it less time to dip, and it hits the crossbar. 

With acclimatisation, players will learn to hit the ball slightly lower while applying more spin to get the ball around the wall and into the top corner. The shot now crosses the goal line 0.030 seconds (or more than 2 ball diameters) ahead of its equivalent at sea level. If the goalkeeper reacts as he would at sea level, the ball would be in the back of the net before he gets to it. 

Azteca Stadium in Mexico City, which is 2288 metres above sea level. 

According to the data, provided by UK-based football performance analysts Prozone, the number of shots from outside the penalty area increased with altitude while the number of shots from inside the area decreased. The implication is that, at altitude, players might be coached to have a go at goal from longer distances to take advantage of the straighter, faster trajectories. 

It is worth noting that in the 1986 World Cup in Mexico, the last time altitude was a factor, eventual winners Argentina played all their matches above 2000 metres. All the other leading contenders had to change altitude. Did that give Argentina an advantage? If it did, it won't happen this year. Whoever wins the tournament will have switched from altitude to sea level and back again at some point. 

The key message for the World Cup, then, is that teams need to take into account transition, acclimatisation and tactics. Players will need to adapt to changes in altitude, especially the effect this has on the flight of the ball. Teams that use high altitude to their advantage - or that are already used to switching from low to high altitude - will profit. That points to a win for a South American team. 

Well.  I think you’d say that New Scientist are probably on their way to the bookies right now.  All this is very relevant though and I thought it was worth sharing it with you.Argentina demonstrated in their 6-1 loss to Bolivia in qualifiers what an impact altitude can have.......taking nothing away from Bolivia that night though, Argentina were shy-ite.

"I'll have a tenner on Chile"

Of course what we also need to factor in to all this is that ball.  

Everyone and their granny has been complaining about it already, so IBWM donned it's best kipper tie and went at the blackboard in true Open University fashion.

Sines, cosines, lambda x, pi and a cheese pastie were all involved and I threw in some of those percentages that new scientist mentioned above regarding density etc.  

The result?  

Well according to IBWM's calculations, just about every game should resemble the last five minutes of cheggers plays pop, with balls flying around all over the place.......and Fabio Capello saying "away you go.....".

But if a team's problems start after they've come back down from altitude, then England could well find that their game against Algeria might be a bit sticky, having just dropped the bast part of 2000 metres in 6 days.  Things are a bit more straightforward for Diego's mob....although being brought down to sea level for a semi final might just add to the mix.

Should be a laugh though.......