Background:​ Soccer is a popular youth sport in the United States and around the world and is unique in the fact that players can use their heads to advance the ball in play;​ a skill known as heading. Recently, along with the common concerns about risk of concussion, there has been worry and speculation involving the repetitive nature of soccer heading and the possible short- and long-term effects, if any, associated with them. Regarding this concern, the United States Soccer Federation implemented soccer heading guidelines for youth players despite no supporting evidence that eliminated heading in those 10 years old and younger and restricted the number of headers in practice for those 11-13 years old. Youth soccer players tend to head the ball at a low frequency that typically increases with age and with boys heading the ball more often than girls. In youth who visit the emergency department for soccer-related injuries, 14% of head injuries are concussions with females at a 2 times greater risk of sustaining a concussion compared to males. Concussed athletes perform worse than healthy controls on clinical outcome measures such as symptoms, balance tests, and neurocognitive function. These measures are also utilized to study the effects of soccer heading.

Purpose:​ The purpose of this study was to determine heading exposure and measure concussion assessment outcomes from pre- to postseason in a youth soccer population. This study also aimed to assess the reliability and validity of a weekly and season-long soccer heading recall questionnaire in this youth population.

Methods:​ For aim 1, 10 male and 10 female games for the Under-12 (U12), U13, and U14 age groups were filmed at a large weekend soccer tournament. Film was utilized to quantify heading exposure for each group. For aim 2, 61 female youth soccer players (age:​ 11.9±0.8 years;​ height:​ 154.2±8.2 cm;​ mass:​ 48.0±10.4 kg) in the U12-U14 age groups completed self-reported symptoms, balance, and neurocognitive testing pre- and post-season. Heading exposure was quantified through the filming of practices and games. For aim 3, 5 males and 25 females completed the season-long recall questionnaire while 21 females completed a total of 77 weekly recall questionnaires. Heading exposure during the soccer season was quantified through the filmed practices and games.

Results:​ Our findings suggest that males (14.2 headers/game) headed the ball more frequently than females (5.1 headers/game). The U14 males had the highest heading exposure at 19.2 headers/game while the U12 females had the lowest heading exposure at 3.00 headers/game. Slight improvements in neurocognitive functioning and gait were demonstrated from pre- to post-season while there were small deficits observed in static balance. Overall, heading exposure did not predict a change in concussion assessment measurements. The weekly soccer heading recall questionnaire demonstrated excellent agreement of .832 and a positive strong correlation of .736 between the number of headers recorded and those recalled by the youth soccer players.

Discussion:​ Heading exposure levels in the youth population are low compared to those seen at the high school, college, and professional levels. The majority of youth soccer players (92.4% of all players) only headed the ball at most 1 time per game. The small changes seen in neurocognitive functioning and gait were likely due to a practice effect. The low amount of heading exposure in our youth soccer cohort had no effect on concussion assessment outcomes suggesting that potential changes may only be seen in the older soccer populations (high school, collegiate, and professional) who have higher levels of heading exposure. It is also possible that the clinical tools utilized were not sensitive enough to capture changes that did occur. The weekly heading recall questionnaire is a tool that can be utilized by researchers in future studies to estimate youth heading exposure but keeping in mind that all soccer players tend to overestimate heading exposure.