title: "Heading" and neck injuries in soccer: a review of biomechanics and potential long-term effects.
abstract: BACKGROUND
  Although soccer has a lower injury rate than does American football, injuries to the head and neck do occur. Indeed, soccer is classified as a contact sport. The potential for cervical injuries from the maneuver known as "heading" are of particular concern. This review provides a synopsis of soccer-related head and neck injuries, an overview of the biomechanics of trauma, and a rational approach to evaluating patients.
  
  
  OBJECTIVE
  This review was conducted to assess and evaluate existing literature on the biomechanics of the act of heading in soccer and the potential for acute and long-term injury to the head and neck.
  
  
  METHODS
  The resulting work is based on literature searches of the PubMed and Medline databases, textbook reviews, and bibliographies of articles and textbooks obtained during the search. Findings from several studies were summarized and critiqued. Biomechanics, anatomy, pathophysiology, and their relation to the act of heading in soccer were also synthesized into the discussion. Relevant studies of athletes in other sports where activity can affect the neck and head in a manner similar to heading were also considered.
  
  
  RESULTS
  The act of heading in soccer involves the athlete's entire body, and studies have used electromyography to define the activity of neck musculature during heading. The majority of head and neck injuries in soccer occur secondary to impacts other than those that occur during heading, however, rare case reports of serious injury exist. Degenerative bony changes in the cervical spine of soccer players have been noted in a few studies, but the connection with heading is not well established. Data from research in other sports, particularly American football and rugby, suggest a predisposition to degenerative disease of the neck secondary to axial loading mechanisms; the exact relevance of these studies to heading and soccer is unclear.
  
  
  CONCLUSIONS
  The complex biomechanics of heading in soccer are not completely defined, especially with regard to long-term effects on the neck and cervical spine. Existing studies of long-term effects suggest a predisposition to degenerative changes of the cervical spine, though they are somewhat limited, even when coupled with data regarding athletes in other sports. Further research in this area is needed with studies that assess biomechanical forces under simulated play conditions and control for impacts and stresses to the neck and spine that occur from non-heading activity.
authors.affiliation: Department of Physical Medicine and Rehabilitation, UMDNJ-New Jersey Medical School, 30 Bergen Street, ADMC 101, Newark, NJ 07103, USA. mehnermi@umdnj.edu
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Mehnert
authors.forename: Thomas
authors.initials: T
authors.lastname: Agesen
authors.forename: Gerard A
authors.initials: GA
authors.lastname: Malanga