Football players suffer more injuries when their team is ahead

Male football players are at a greater risk of injury five minutes after a card has been given or after a goal has been scored. The frequency of player injuries also increases when their own team is in the lead. These are the findings of researchers at the Sahlgrenska Academy, who, in collaboration with Fifa, have analysed injuries over the last three World Cup tournaments.

Football players do not just injure themselves whenever and however. On the contrary, injury frequency follows a clear pattern that is dependent on how various events in the course of a match affect players' emotional and physical states.

This is borne out by three new studies conducted at University of Gothenburg's Sahlgrenska Academy with the support of the international football association, FIFA.

The studies, which are based on injury statistics from the 2002, 2006 and 2010 World Cup tournaments for men, and which were published in the British Journal of Sports Medicine, show that:

• Injury frequency varies depending on whether a team is winning, losing or if the outcome is not yet decided. Players in winning teams are at the greatest risk of injury.

"This may be due in part to the fact that a losing team starts to play more aggressively," says Jaakko Ryynänen, a PhD student at the Sahlgrenska Academy who contributed to the study.

• The risk of injury varies between the various positions, the frequency of injury being greatest amongst strikers:

"One possible cause is that the results of any one match are very important in international tournaments. This may accentuate the role of the strikers, leading to increased pressure on them," says Jaakko Ryynänen.

• There is a direct link between the number of free kicks and the number of injuries per match. A match with more free kicks has a higher injury frequency.
• Injury frequency increases within a five minute period after a yellow or red card is issued, and following injuries and goals.

"One theory is that players lose their concentration following disruptive breaks in play, which then increases the risk of injury," says Jaakko Ryynänen.

A surprising finding is that the number of injuries per World Cup match increases if there is a longer break between matches.

"It sounds contradictory that the risk of injury increases with longer recovery times, but our theory is that this may be due to players losing their focus on match games after a break of several days. Perhaps teams also play at a higher level of intensity after they have rested for a number of days and have more energy."

According to Jaakko Ryynänen these studies are important in terms of being able to prevent injuries.

"Our primary goal is to contribute with knowledge that can prevent injuries. The ability to recognise periods of matches when the injury incidence is high may be important in terms of preventive measures, for example replacing players at risk of suffering a repeat of a previous injury. Since there are more than 260 million football players in the world, preventive measures could help a lot of people. "

Continued research could also result in new rules. Jaakko Ryynänen mentions as one example the introduction of temporarily sending off players for aggressive behaviour, as is the case with ice hockey.

"This is something for the governing bodies of football to consider. For our part, we will continue our research in order to identify more opportunities for injury prevention, and to see whether the conclusions we draw are also applicable to football at lower levels. "