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Introduction: Repetitive head impacts (RHI) from routine soccer (football) heading have been suggested to contribute to the long-term development of neurodegenerative disorders. However, scientific evidence concerning the actual risk of these RHI on brain health remains inconclusive. Moreover, female athletes--despite a presumably increased vulnerability toward the effects of RHI--are largely underrepresented in previous approaches. Therefore, our aim was to prospectively investigate the effects of heading on cognitive and sensorimotor performances, health perception, and concussion symptoms in semi-professional female soccer players. Methods: An extensive test battery was used to assess cognitive and sensorimotor performances as well as health status (SF-36) and concussion symptoms (SCAT3) of a total of 27 female soccer players (22.2 - 4.2 years) and 15 control subjects (23.2 - 3.0 years) before and after one-and-a-half years. Throughout this period, soccer players' heading exposure was determined using video analysis. Results: Subgroup comparisons (control [n = 12], low exposure [n = 7], high exposure [n = 8]) showed no time-dependent differences in SF-36 or SCAT3 scores. Similarly, across most behavioral tests, soccer players' performances evolved equally or more favorably as compared to the control subjects. However, there were significant effects pointing toward slightly negative consequences of heading on aspects of fine motor control (p = 0.001), which were confirmed by correlation and multiple regression analyses. The latter, further, yielded indications for a relationship between heading exposure and negative alterations in postural control (p = 0.002). Discussion: Our findings do not provide evidence for negative effects of soccer heading on female players' health perception, concussion symptoms, and cognitive performances over the course of one-and-a-half years. However, we found subtle negative alterations in fine motor and postural control that could be attributed to heading exposure. Other factors, like the number of previous head injuries, were not linked to the observed changes. Given the reduction of our initial sample size due to player fluctuation, the results need to be interpreted with caution and validated in larger-scale studies. These should not only focus on cognitive outcomes but also consider sensorimotor changes as a result of RHI from soccer heading. [ABSTRACT FROM AUTHOR]

Introduction: Repetitive subconcussive head impacts can lead to subtle neural changes and functional consequences on brain health. However, the objective assessment of these changes remains limited. Resting state blinkrelated oscillations (BROs), recently discovered neurological responses following spontaneous blinking, are explored in this study to evaluate changes in BRO responses in subconcussive head impacts. Methods: We collected 5-min resting-state electroencephalography (EEG) data from two cohorts of collegiate athletes who were engaged in contact sports (SC) or non-contact sports (HC). Video recordings of all on-field activities were conducted to determine the number of head impacts during games and practices in the SC group. Results: In both groups, we were able to detect a BRO response. Following one season of games and practice, we found a strong association between the number of head impacts sustained by the SC group and increases in delta and beta spectral power post-blink. There was also a significant difference between the two groups in the morphology of BRO responses, including decreased peak-to-peak amplitude of response over left parietal channels and differences in spectral power in delta and alpha frequency range post-blink. Discussion: Our preliminary results suggest that the BRO response may be a useful biomarker for detecting subtle neural changes resulting from repetitive head impacts. The clinical utility of this biomarker will need to be validated through further research with larger sample sizes, involving both male and female participants, using a longitudinal design. [ABSTRACT FROM AUTHOR]

Soccer is regarded as the most popular sport in the world, with millions of people actively involved in the game. Being a contact sport in nature, soccer players are susceptible to various kinds of injuries, such as lower extremities muscle injury. In addition to those familiar injuries that soccer players sustain during the game, traumatic brain injury is also a possibility. Head impacts in soccer could be a result of head-to-head impact with an opponent player, a headto-elbow impact, an impact with the goal post, an impact with the ground, as well as an impact with the soccer ball, which occurs during a heading manoeuvre. Soccer allows the players to use their heads to hit the ball to pass it to a teammate or even perform heading to score a goal. Although soccer heading is perceived as less harmful as compared to head impacts with other hard objects, many studies have shown compelling evidence that this repetitive heading might harm the brain, thereby leading to traumatic brain injury. Protective headgears designed especially for soccer players have been commercially available in the market for some years. However, the effectiveness of these headgears in reducing the impact due to soccer heading has not been well studied. This paper investigates the effectiveness of two commercially available headgears, the Full90 and the ForceField headgear by means of a heading experiment. An anthropometric test device known as Hybrid III head and neck dummy instrumented with an inertial sensor that consists of a triaxial accelerometer and gyroscope installed at the centre of gravity of the head was used in the experiment. A soccer ball launching machine was used to propel the ball at several inbound velocities. Peak linear acceleration (PLA) and peak angular acceleration (PRA) were recorded, and the head injury criterion (HIC) and the rotational injury criterion (RIC) were calculated. It was found that both headgears failed to reduce the linear components of head acceleration but instead increased the HIC (13 - 66% increment) depending on the inbound ball velocity. With respect to the rotational component of head injury, the Full90 headgear was found to reduce the RIC up to 29%, but the ForceField failed to provide a significant reduction of RIC. Overall, both headgears were found to be ineffective in reducing linear and rotational components of head injury, which could be attributed to the headgear design. Improved headgear design and an improved padded foam are needed to protect soccer player's brain while performing soccer heading. [ABSTRACT FROM AUTHOR]

Soccer is a unique sport where players purposefully and voluntarily use their unprotected heads to manipulate the direction of the ball. There are limited soccer head impact exposure data to further study brain injury risks. The objective of the current study was to combine validated mouthpiece sensors with comprehensive video analysis methods to characterize head impact exposure and biomechanics in university varsity women's soccer. Thirteen female soccer athletes were instrumented with mouthpiece sensors to record on-field head impacts during practices, scrimmages, and games. Multi-angle video was obtained and reviewed for all on-field activity to verify mouthpiece impacts and identify contact scenarios. We recorded 1307 video-identified intentional heading impacts and 1011 video-verified sensor impacts. On average, athletes experienced 1.83 impacts per athlete-exposure, with higher exposure in practices than games/scrimmages. Median and 95th percentile peak linear and peak angular accelerations were 10.0, 22.2 g, and 765, 2296 rad/s2, respectively. Long kicks, top of the head impacts and jumping headers resulted in the highest impact kinematics. Our results demonstrate the importance of investigating and monitoring head impact exposure during soccer practices, as well as the opportunity to limit high-kinematics impact exposure through heading technique training and reducing certain contact scenarios. [ABSTRACT FROM AUTHOR]

Assessing heading exposure in football is important when exploring the association between heading and brain alterations. To this end, questionnaires have been developed for use in adult populations. However, the validity of self-report in adolescents remains to be elucidated. Male youth soccer players (n = 34) completed a questionnaire on heading exposure after a two-week period, which included matches and training sessions. Self-reported numbers were compared to observation (considered reference). In total, we observed 157 training sessions and 64 matches. Self-reported heading exposure correlated with observed heading exposure (Spearman's rho 0.68; p < 0.001). Players systematically overestimated their heading exposure by a factor of 3 with the random error of 46%. Area under the curve was 0.87 (95% CI 0.67–1) utilizing self-report for identifying players from high- and low-exposure groups. Thus, in this study, self-reported data could be used to group youth players into high and low heading exposure groups, but not to quantify individual heading exposure. [ABSTRACT FROM AUTHOR]

The purpose of this study was to examine the potential effect modifying role of the BDNF Val66Met polymorphism on the association of soccer heading with white matter microstructure. We studied 312 players enrolled in the ongoing Einstein Soccer Study, a longitudinal study of amateur soccer player in New York City and surrounding areas. At enrollment and 2 years later, total heading in the prior 12 months (12-mo.) was estimated using an established self-report instrument and diffusion tensor imaging (DTI) was performed. Generalized Estimating Equations (GEE) logistic regression models were employed to test effect modification by the BDNF Val66Met polymorphism on the association between 12-mo. heading exposure and DTI. We identified a significant interaction of 12-mo heading*BDNF Val66Met genotype on the presence of low Radial Diffusivity, a DTI marker associated with myelination. Only Met (+) players demonstrated significantly reduced odds of low RD [OR (95 % CI): −2.36 (−3.53, −1.19)] associated with the highest vs. lowest quartile of 12-mo heading exposure. BDNF Val66Met (+) soccer players with long-term exposure to high levels of heading exhibit less low Radial Diffusivity, suggesting impaired re-myelination may be a substrate of the previously reported association between heading and poor functional outcomes in soccer players. [ABSTRACT FROM AUTHOR]

Heading occur frequently in soccer games and studies have shown that repetitive heading of the soccer ball could result in degeneration of brain cells and lead to mild traumatic brain injury. This study proposes a two degree-of-freedom linear mathematical model to study the impact of the soccer ball on the brain. The model consists of a mass-spring-damper system, in which the skull, the brain and the soccer ball are modelled as a mass and the neck modelled as a spring-damper system. The proposed model was compared with previous dynamic model for soccer ball-to-head impact. Moreover, it was also validated against drop ball experiment on an instrumented dummy skull and also compared with head acceleration data from previous studies. Comparison shows that our proposed model is capable of describing both the skull and brain accelerations qualitatively and quantitatively. This study shows that a simple linear mathematical model can be useful in giving a preliminary insight on the kinematics of human skull and brain during a ball-to-head impact. The model can be used to investigate the important parameters during soccer heading that affect the brain displacement and acceleration, thus providing better understanding of the mechanics behind it. [ABSTRACT FROM AUTHOR]

This study compared changes in neurocognitive performance and symptom reports following an acute bout of soccer heading among athletes with and without protective soccer headgear. A total of 25 participants headed a soccer ball 15 times over a 15-minute period, using a proper linear heading technique. Participants in the experimental group completed the heading exercise while wearing a protective soccer headband and controls performed the heading exercise without wearing the soccer headband. Neurocognitive performance and symptom reports were assessed before and after the acute bout of heading. Participants wearing the headband showed significant decreases on verbal memory (p= 0.02) compared with the no headband group, while the no headband group demonstrated significantly faster reaction time (p= 0.03) than the headband group following the heading exercise. These findings suggest that protective soccer headgear likely does not mitigate the subtle neurocognitive effects of acute soccer heading. [ABSTRACT FROM AUTHOR]

Primary objective: The purpose of this study was to investigate the relationship between soccer heading and computerized neurocognitive performance and symptoms in female and male youth soccer players. Research design: Cross-sectional and prospective design. Methods and procedures: A total of 63 (27 females, 36 males) youth soccer players aged 13-18 years ( M == 15.89, SD == 1.17) participated in the study. Participants completed the Immediate Post-concussion Assessment and Cognitive Test (ImPACT) and symptom report. Main outcomes: Computerized neurocognitive performance (e.g., verbal and visual memory, motor processing, and reaction time) and symptoms. Results: There were no differences in neurocognitive performance or symptoms among low-, moderate-, and high-exposure header groups. The current sample outperformed the 10th percentile norms for neurocognitive and symptom scores. Males headed the ball more frequently and reported lower verbal and visual memory and motor processing speed scores than females. Conclusion: The current findings did not support a relationship between soccer heading and computerized neurocognitive performance and symptoms. The researchers suggest that any purported effects of soccer heading in youth are subtle and may affect only a small number of athletes. The reported sex differences in heading exposure warrant further attention. [ABSTRACT FROM AUTHOR]

This study develops a dynamic model of head acceleration, which incorporates physiologically related neck muscle contributions, to further the understanding of the mechanical behaviour of the head-neck system during soccer heading. An inverted pendulum is combined with a linear visco-elastic element to model the head-neck system following a half-sine input force. Model parameter values were varied to obtain agreement with previously published experimental data (Naunheim et al., 2003), and were subsequently compared to literature values. The model predicted the same mechanical angular kinematics as observed experimentally both during and post impact. The greatest acceleration was in the anterior direction at the instant the ball left the head, attributed to the elastic stiffness of the neck musculature. The head-neck stiffness and damping coefficients determined from the model (350 N m rad-1 and 4 N m s rad-1, respectively) were similar to those reported elsewhere when subjects were asked to resist maximally. The model may be subsequently used to investigate differences in technique and ability with respect to the salient model parameters to further our biomechanical understanding of soccer heading. [ABSTRACT FROM AUTHOR]

This study investigated the presence of neuropsychological deficits associated with hitting the ball with one’s head (heading) during soccer play. A neuro-cognitive test battery was administered to 60 male soccer players, high school, amateur and professional level, and 12 nonplaying control participants. The effects of currently reported heading behavior as well as that of estimated lifetime heading experience on neuropsychological test performance were examined. Players with the highest lifetime estimates of heading had poorer scores on scales measuring attention, concentration, cognitive flexibility and general intellectual functioning. Players’ current level of heading was less predictive of neuro-cognitive level. Comparison of individual scores to age-appropriate norms revealed higher probabilities of clinical levels of impairment in players who reported greater lifetime frequencies of heading. Because of the worldwide popularity of the game, continued research is needed to assess the interaction between heading and soccer experience in the development of neuropsychological deficits associated with soccer play. [Copyright &y& Elsevier]