Published by Di Virgilio and colleagues in EBioMedicine in November 2016
Summary by Dr L M Li
Introduction:
Players often head the ball whilst playing soccer. Some scientists and doctors are concerned that heading the ball can produce brain injuries with longterm effects. However, millions of people worldwide play soccer (and head the ball) with no ill effects. There has been very little research into the effects of heading a football. In this study, Di Virgiolio and colleagues studied what happens to the brain after heading a football.
Methods:
In this study, 19 amateur soccer players headed a football 20 times over 10 minutes. This was designed to mimic what players might do during heading practice in training. Then each player was assessed immediately after the heading, 24 hours, 48 hours and 2 weeks later. The players had two types of tests. The first type were computerized tests designed to assess cognitive function (memory, decision making, planning etc.). The second type used a nerve stimulation technique called Transcranial Magnetic Stimulation (TMS) to test nerve function.
Results:
After heading the ball, players had lower scores on two memory tests. The TMS tests also showed increased GABA activity in the nerves controlling movement. GABA is a major inhibitory chemical in the brain and is thought to be important in reducing neuronal activity. The changes in the memory scores and the TMS tests were completely gone by 24 hours.
Conclusion:
The researchers concluded that a single standard heading practice session can produce changes in memory function and brain function. These changes are temporary. The researchers suggest that the increased GABA activity in the brain after the heading session may reflect the brain protecting itself against minor injury.
There are some limitations to think about. First, this was an extremely small study (with only 19 players studied). Second, the TMS tests used are only one way to assess brain activity. It can be difficult to interpret what the tests actually mean for the brain, whether it truly is a reflection of injury. Thirdly, there was no comparison group doing another activity, so there is a possibility that the changes are not because of heading the ball but because of, for example, increased physical activity.
There are very few studies which have studied what happens in the brain after sporting head contact which does not cause a player to be ‘knocked out’. This study is important because it raises some interesting questions.
First, these players were amateur – professional players may have different heading technique or frequency, which might affect the brain differently. Second, these players have played football before so the effects of heading may not be the same for those who have never played football e.g. children starting the sport for the first time. Third, how do the changes in memory and TMS tests translate into the ‘real world’, do the players themselves feel any different? Should, as the researchers suggest, student players be banned from playing football/ heading the ball the day before an exam? Finally, if the TMS tests do indeed reflect brain injury, what would be the effects of a second knock to the head during the first 24 hours?
American football, rugby and soccer are all contact sports, where players frequently get knocks to the head. There is increasing awareness that even minor knocks can produce problems, because they occur so frequently. These are all areas of active research and will be important to help keep players safe whilst taking part in sport.
Summary by Dr L M Li
Introduction:
Players often head the ball whilst playing soccer. Some scientists and doctors are concerned that heading the ball can produce brain injuries with longterm effects. However, millions of people worldwide play soccer (and head the ball) with no ill effects. There has been very little research into the effects of heading a football. In this study, Di Virgiolio and colleagues studied what happens to the brain after heading a football.
Methods:
In this study, 19 amateur soccer players headed a football 20 times over 10 minutes. This was designed to mimic what players might do during heading practice in training. Then each player was assessed immediately after the heading, 24 hours, 48 hours and 2 weeks later. The players had two types of tests. The first type were computerized tests designed to assess cognitive function (memory, decision making, planning etc.). The second type used a nerve stimulation technique called Transcranial Magnetic Stimulation (TMS) to test nerve function.
Results:
After heading the ball, players had lower scores on two memory tests. The TMS tests also showed increased GABA activity in the nerves controlling movement. GABA is a major inhibitory chemical in the brain and is thought to be important in reducing neuronal activity. The changes in the memory scores and the TMS tests were completely gone by 24 hours.
Conclusion:
The researchers concluded that a single standard heading practice session can produce changes in memory function and brain function. These changes are temporary. The researchers suggest that the increased GABA activity in the brain after the heading session may reflect the brain protecting itself against minor injury.
There are some limitations to think about. First, this was an extremely small study (with only 19 players studied). Second, the TMS tests used are only one way to assess brain activity. It can be difficult to interpret what the tests actually mean for the brain, whether it truly is a reflection of injury. Thirdly, there was no comparison group doing another activity, so there is a possibility that the changes are not because of heading the ball but because of, for example, increased physical activity.
There are very few studies which have studied what happens in the brain after sporting head contact which does not cause a player to be ‘knocked out’. This study is important because it raises some interesting questions.
First, these players were amateur – professional players may have different heading technique or frequency, which might affect the brain differently. Second, these players have played football before so the effects of heading may not be the same for those who have never played football e.g. children starting the sport for the first time. Third, how do the changes in memory and TMS tests translate into the ‘real world’, do the players themselves feel any different? Should, as the researchers suggest, student players be banned from playing football/ heading the ball the day before an exam? Finally, if the TMS tests do indeed reflect brain injury, what would be the effects of a second knock to the head during the first 24 hours?
American football, rugby and soccer are all contact sports, where players frequently get knocks to the head. There is increasing awareness that even minor knocks can produce problems, because they occur so frequently. These are all areas of active research and will be important to help keep players safe whilst taking part in sport.