With 14% of United States runners preferring to train on an motorized treadmill (MT), many clinicians using the MT as a tool in gait-retraining, and its role in the collection of sports science data, it is important to understand the differences between running on an MT and overground(1). A group from the Netherlands wondered what the... MORE
Is playing soccer bad for your brain?
Soccer is the world’s most-played sport. More than 265 million people play soccer each year(1). The number of soccer-related injuries is growing along with the numbers of players. Nearly one-quarter of these injuries are concussions. Of these, almost one-third are related to heading the ball. The rest of the injuries are the result of player-to-player contact.
Soccer players can head the ball anywhere from six to 12 times per game. The numbers go up during a practice session. This repeated cranial micro-trauma is not without repercussions. Brazilian researchers conducted a review of the research on the consequences of repeated heading the ball. Looking at 29 articles from 1981 to 2015, they found heading associated with changes in brain structure, chemistry, and function(1). Due to various study limitations, it is impossible to determine causation definitively. However, with professional soccer players heading the ball over 2000 times in their career, the likelihood of them suffering sub-concussive brain trauma is great.
Repeated cranial trauma can result in any number of neurological pathologies. Some of the more common ones noted in participants of other sports disciplines are Parkinson’s disease, dementia, Alzheimer’s disease, and chronic traumatic encephalopathy (CTE). Just how common these neurodegenerative diseases are in the soccer population is unclear.
Recently (late 2019), researchers at the University of Glasgow published a retrospective cohort study that examined the mortality records of 7676 Scottish former professional soccer players(2). They then compared these records to age and social strata matched controls. They found that former professional soccer players fared better in all-cause mortality, including ischemic heart disease and lung cancer than the controls until the age of 70. However, the soccer players had a higher incidence of death from neurodegenerative diseases.
When reviewing the records of the soccer players, the investigators found that outfielders received prescriptions for dementia-related medications more often than goalies. That’s likely due to increased heading by outfielders compared to goalies. The results of this study are in agreement with other studies comparing soccer athletes with controls. One limitation of this study is the reliance on past medical records. Unfortunately, CTE is a post-mortem diagnosis. Therefore, there may have been undiagnosed CTE unaccounted for in each player’s history.
While clearly, the health benefits of playing soccer outweigh the risks of cumulative brain trauma, preventing injury should be every clinician’s focus. Remember, the United States Soccer Federation bans heading in athletes under 11 years-of-age. Those aged 11 to 13 years old are allowed just 30-minutes of heading practice per week. Physios and trainers should teach neck and core strengthening along with appropriate bracing techniques for heading the ball. Building a stout neck may help absorb the shock of the impact. Plyometric exercises improve jumping and encourage force generation from the legs, not just the neck when heading the ball. Heading will likely never be banned entirely from soccer, but limiting the number of headers and executing the heading maneuver safely may help decrease the long term effects.
- Front Neurol. 21 March 2016;7:38
- 21 October 2019;epub ahead of print