Assessing neuromotor and postural control after repetitive subconcussive soccer headers: A narrative review

Head impacts in sports have received considerable attention in the research and clinical communities over the past two decades due to the known short- and long-term effects on brain and behavioral health. However, most of this research has focused on concussive head impacts despite the observation that nearly all head impacts in sports are subconcussive in nature. To address the latter in a controlled laboratory setting, a soccer heading task has been used to induce subconcussive head impacts and their potential connection to short-term changes in neuromotor and postural control. Despite the increased research in this area, the magnitude and number of headers that are substantial enough to effect neuromotor or postural control in a consistent/reliable manner is unknown. A reason as to why it hasn't been determined is due to the lack of standardized heading protocols and assessments. The purpose of this narrative review was to examine past studies which have tested the neuromotor and/or postural control effects of soccer heading. Three online databases were searched: Google Scholar, PubMed, CINAHL Complete, using the key words "soccer heading", "neuromotor control", and "postural control". Fifteen studies assessed neuromotor and/or postural control before and after a bout of soccer heading. Four of these studies used King-Devick tests to assess neuromotor control while four separate studies used the BESS test to assess postural control. Eleven of the studies reported a decline in neuromotor and/or postural control following repeated soccer headers. One study compared collegiate soccer and non-soccer athletes, showing soccer athletes had less postural control decline following the impacts, while another study evaluated the effectiveness of a soccer heading intervention, which did not show a significant difference. A limitation in this research is the inconsistency of magnitude and number of headers, with some heading bouts not being ideal for assessing neuromotor or postural control changes. In addition, inconsistent results may be explained by the vast difference in the number of impacts, velocity of the ball, and type of assessment. A universal neuromotor and postural control assessment and protocol are needed to further our understanding of subconcussive head impacts.