A lot of studies have researched the consequences of heading a ball in soccer. Does frequent soccer heading lead to cognitive impairment? How does heading affect kids?
An international symposium that involved experts in neurology, neurosurgery, orthopedics, sports medicine, pediatrics, and neurospsychology organized by the Institute of Medicine concluded that soccer heading does not lead to any permanent neuropsychological or visual impairment other than causing transient headaches. However, concussions which occur frequently in the more elite echelons of soccer do cause impairments especially when the athlete has not completely recovered from a previous injury. Most concussions occur when two players challenge for the ball but make physical contact with their heads instead. A lot of goalkeepers for this reason suffer concussions. The Premiership has already seen Petr Cech, Chris Kirkland, and Carlo Cudicini being hospitalized for this injury.
It is recommended that kids should not head the ball till age 10. The use of soccer helmets have not shown to be useful in preventing concussions as these typed of injuries are caused by rotational (angular) shearing torques whereas helmets can only prevent linear translatory forces.
What was interesting to read was that studies by American researchers allayed concerns that soccer heading led to impairment but European studies highlighted otherwise. Given the litigious nature of American society, this emphasis was quite surprising. However, the population of the American and European studies were quite different, with the Americans focusing more on children and college level soccer players while the Europeans studies involved professional soccer players. The Europeans found that soccer players who headed the ball more often and who had concussions scored less well in neuropsychological tests as compared to athletes in non-contact sports. Moreover the nature of these deficits were different for the two groups. Headers were likely to have decrements in visual and verbal memory as well as eye tracking speed, whereas the cognitive deficits in concussion had to do with attention, planning and fine visual discrimination.
However it is not clear whether these deficits are all that different as impaired memory, disorientation, and delayed responses are also part of the symptomatology of concussion. The caveat is that those players who head frequently also increase their chances of a concussion occurring. The drop off in the neuropsychological tests in the headers may reflect prior concussions.
What should allay the concerns of parents with kids who want to play soccer is that none of the children examined exhibited problems. For a youth player to get seriously injured the ball has to travel at speeds of about a 100 km/hour (52.5 mph). Usually at that age a well struck ball generates a maximum of 40 km/hour (25 mph), well below the danger level.
An interesting study by Dr Donald Kirkendall, a sports medicine specialist at the UNC School of Medicine that is due out this year is a longitudinal study that follows players between the ages of 16-21 years in the US National Youth teams over a period of five years which should conclusively settle the question as to whether heading the ball leads to brain injury. This is the first study that follows a group of elite soccer players over such a lengthy period of time.