The neurophysiological response following sub-concussive soccer heading

Concussion is the most common type of traumatic brain injury (Shaw, 2002). Research into concussion has significantly increased in the past decade reflecting the growing recognition of repeated head-injuries in sport. Whilst the focus of the research has centred on those who have been concussed, there is also increasing awareness regarding the effects of sub-concussion.Defined as events that occurwhen there is an apparent brain insult with insufficient force to produce clinical symptoms that are characteristic of concussion (Gysland et al., 2012), sub-clinical acute effects of sub-concussion are relatively unknown. At present it has been suggested that exposure to repetitive, sub-concussive events may result in persistent cognitive or motor impairments, and behavioral changes (McKee et al., 2014) associated to long-term neurophysiological changes due to cumulative effects (Pearce et al., 2014). Moreover, there have been suggestions of the possibility that high numbers of repetitive sub-concussions, more than concussions, contributes to increased risk of neurodegenerative diseases including Alzheimer's or chronic traumatic encephalopathy (McKee et al., 2014; Smith et al., 2013).