Concussions and heading in soccer: a review of the evidence of incidence, mechanisms, biomarkers and neurocognitive outcomes.
BACKGROUND
Soccer is currently the most popular and fastest-growing sport worldwide. Similar to many sports, soccer carries an inherent risk of injury, including concussion. Soccer is also unique in the use of 'heading'. The present paper provides a comprehensive review of the research examining the incidence, mechanisms, biomarkers of injury and neurocognitive outcomes of concussions and heading in soccer.


METHODS
Seven databases were searched for articles from 1806 to 24 May 2013. Articles obtained by the electronic search were reviewed for relevance, with 229 selected for review. Ultimately, 49 articles met criteria for inclusion in the present review.


RESULTS
Female soccer players have a higher incidence of concussions than males. The most frequent injury mechanism is player-to-player contact for both genders. Few studies examined the effects of concussion in soccer players; however, neurocognitive outcomes were similar to those reported in the larger sport concussion literature, while the effect of heading is less clear.


CONCLUSIONS
Despite variation in research designs and study characteristics, the outcomes of concussions in soccer align with the greater concussion literature. This review makes recommendations for future research to increase standardization of research for improved understanding of concussions in soccer as well as the effects of heading.
Institute of Medical Sciences, University of Toronto , Toronto, Ontario , Canada .
Monica E
ME
Maher
Michael
M
Hutchison
Michael
M
Cusimano
Paul
P
Comper
Tom A
TA
Schweizer
D000293:Adolescent; D000328:Adult; D001265:Athletic Injuries / Q000150:complications / Q000453:epidemiology / Q000503:physiopathology; D015415:Biomarkers / Q000378:metabolism; D001924:Brain Concussion / Q000150:complications / Q000453:epidemiology / Q000503:physiopathology; D003072:Cognition Disorders / Q000453:epidemiology / Q000209:etiology / Q000503:physiopathology; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D010751:Phosphopyruvate Hydratase / Q000378:metabolism*; D020127:Recovery of Function; D012307:Risk Factors; D064568:S100 Calcium Binding Protein beta Subunit / Q000378:metabolism*; D017678:Sex Distribution; D012737:Sex Factors; D012916:Soccer / Q000293:injuries; D014481:United States / Q000453:epidemiology
D015415:Biomarkers; D064568:S100 Calcium Binding Protein beta Subunit; D010751:Phosphopyruvate Hydratase