The acute neuropsychological effects of heading in soccer: a pilot study

Mechanical and Contractile Properties of Knee Joint Muscles after Sports-Related Concussions in Women Footballers

The purpose of this study was to determine if women footballers have an increased lack of neuromuscular control of the knee joint after a concussion compared to a healthy cohort tested with tensiomyography (TMG). Forty-one female collegiate footballers were enrolled in this study from which there were 20 with a history of sports-related concussions (SRCs) and 21 control subjects. Results from the SRC group had significantly higher Tc (ms) (z = -5.478, p = 0.000) and significantly lower Dm (mm) (z = -3.835, p = 0.000) than the control group in the case of the rectus femoris muscle. The SRC group had significantly higher Tc (ms) (z = -2.348, p = 0.016) and significantly lower Dm (mm) (z = -4.776, p = 0.000) than the control group in the case of the vastus medialis muscle. The SRC group had significantly higher Tc (ms) (z = -5.400, p = 0.000) and significantly lower Dm (mm) (z = -4.971, p = 0.000) than the control group in the case of the vastus lateralis muscle. The SRC group had significantly higher Tc (ms) (z = -5.349, p = 0.000) than the control group in the case of the biceps femoris muscle response, whereas no significant difference was found in Dm (mm) (z = -0.198, p = 0.853) between the groups. The results of the current study may have implications for current practice standards regarding the evaluation and management of concussions and can add valuable information for knee prevention programs as well.

Heading and risk of injury situations for the head in professional German football: a video analysis of over 150,000 headers in 110,000 match minutes

To provide detailed epidemiological data on situations with a propensity of head injuries due to heading in professional football. In a prospective cohort study including the four highest professional football leagues in Germany, headers carried out in 1244 official matches and critical situations (CI) with a potential risk for injuries over one season were assessed by video analysis and a standardised video protocol. Results: 154,766 headers in 111,960 match minutes were recorded (1.4 headings/min). Video analysis showed a mean of 6.2 headers per field player and match (SD: 2,9; min: 0; max: 19) in the entire study population with a peak in the third league (7.1 per player and match). Headers were predominantly carried out with the forehead (78.5%), and nearly two-thirds occurred during defence (64.3%). 49.9% of all headers occurred during tackling, of which 78.3% involved body contact with an opponent. Video analysis yielded 848 CI. 74.5% of all critical incidents occurred during heading duels as a part of tackling (odds ratio: 3.6, 95%-CI: 2.4-5.2), and 99.4% involved body contact (odds ratio: 5.9, 95%-CI: 2,8-12,7). This study is the first to provide detailed epidemiological data on heading and critical incidences with high risk for head injuries in professional football. Heading duels bear a high risk of head injury and thus represent a key target for prevention strategies. The impacts of headers should be critically investigated regarding neurological consequences in further studies, by including the mean heading rate per mal field player and match.

Neurophysiological Effects of Repeated Soccer Heading in Youth

Repeated head loading in sports is associated with negative long-term brain health, and there is growing evidence of short-term neurophysiological changes after repeated soccer heading. The objective of this study was to quantify the head kinematics and effects of repetitive soccer headers in adolescents using an instrumented mouthguard. Adolescent soccer players aged 13-18 years were randomly assigned to a kicking control, frontal heading, or oblique heading group. Participants completed neurophysiological assessments at three-time points: immediately prior to, immediately after, and approximately 24 h after completing 10 headers or kicks. The suite of assessments included the Post-Concussion Symptom Inventory, visio-vestibular exam, King-Devick test, modified Clinical Test of Sensory Interaction and Balance with force plate sway measurement, pupillary light reflex, and visual evoked potential. Data were collected for 19 participants (17 male). Frontal headers resulted in significantly higher peak resultant linear acceleration (17.4 ± 0.5 g) compared to oblique headers (12.1 ± 0.4 g, p < 0.001), and oblique headers resulted in significantly higher peak resultant angular acceleration (frontal: 1147 ± 45 rad/s2, oblique: 1410 ± 65 rad/s2, p < 0.001). There were no neurophysiological deficits for either heading group or significant differences from controls at either post-heading timepoint, and therefore, a bout of repeated headers did not result in changes in the neurophysiological measures evaluated in this study. The current study provided data regarding the direction of headers with the goal to reduce the risk of repetitive head loading for adolescent athletes.

Video analysis of 100 matches in male semi-professional football reveals a heading rate of 5.7 headings per field player and match

INTRODUCTION

Heading is an integral part of football and frequent media reports and previous studies about potential danger of heading and head trauma in football fuelled discussions. Epidemiological data and video analyses regarding headings situation and associated head injuries are still missing in male adult professional football.

METHODS

In a prospective cohort study in the male fourth German football league, 100 official matches of the 2015-2016 season were assessed by video analysis and a standardized protocol. Heading situations and concomitant circumstances as well as incidents with a propensity of injury (critical incidents) were analyzed. Critical incidents (CI) and seasonal reported head injuries were cross-referenced.

RESULTS

Overall, 11,514 headings were analysed in detail. Video analysis yielded a mean of 5.7 headings per player and match (SD: 1.2; range 0-15). Heading was predominantly performed with the frontal part of the head (76.8%), and nearly two thirds of all headings occurred during defending (65.8%). 71.0% of all headings occured during tacklings, of which 71.9% involved body contact with the opponent player. Video analysis yielded 31 CI on the head due to heading (incidence: 1.02 per 1000 h match exposure and player). 29 CI occurred during heading duels (odds ratio: 5.91), 30 CI with body contact (odds ratio: 28.8) and 6 CI with elbow contact (odds ratio: 6.13).

CONCLUSION

Heading frequency in male semi-professional football could be determined with a rate of 5.7 headings per match and field player. Cross referencing CI and seasonal reported head injuries revealed a very low number of reported head injuries.

Heading in the Right Direction: A Critical Review of Studies Examining the Effects of Heading in Soccer Players

The practice of heading in soccer has become a public concern because of the potential for subconcussive impacts to cause cumulative concussive-like effects; however, experimental evidence for this hypothesis has been mixed. This systematic review used pre-defined search parameters to assess primary literature that examined changes in cognitive, behavioral, structural, and/or biological processes after acute heading exposure in youth and young adult soccer players. The findings were synthesized into a concise and comprehensive summary of the research following the preferred reporting items for systematic reviews and meta-analyses (PRISMA) format, and suggestions for standardization of acute heading protocols are described. A total of 1189 articles were considered for this review, with 19 articles meeting all of the inclusion criteria for full analysis. An attempt was made to identify methods with significant sensitivity and reliability by grouping studies based on their outcome measures. Because of lack of standardization across intervention types and data collection protocols, no sensitive and reliable methods could be identified conclusively to assess the effects of acute heading exposure in soccer players. Based on this review, there is not enough evidence to either support or refute the potential of effects of subconcussive events from acute soccer heading exposure. Recommendations for standardization of acute heading exposure studies based on the included literature are discussed. Standardization is required to better understand the impact of acute heading exposure in soccer players, while allowing for the development of guidelines that mitigate any potential risks and allowing athletes to remain active and develop their skills.

Concussion in soccer: a comprehensive review of the literature

Sports-related concussion has been examined extensively in collision sports such as football and hockey. However, historically, lower-risk contact sports such as soccer have only more recently garnered increased attention. Here, we review articles examining the epidemiology, injury mechanisms, sex differences, as well as the neurochemical, neurostructural and neurocognitive changes associated with soccer-related concussion. From 436 titles and abstracts, 121 full texts were reviewed with a total of 64 articles identified for inclusion. Concussion rates are higher during competitions and in female athletes with purposeful heading rarely resulting in concussion. Given a lack of high-level studies examining sports-related concussion in soccer, clinicians and scientists must focus research efforts on large-scale data gathering and development of improved technologies to better detect and understand concussion.

A pilot study of diffusion tensor imaging metrics and cognitive performance pre and post repetitive, intentional sub-concussive heading in soccer practice

Background

Although soccer players routinely head the ball in practice and games, recent research has suggested that cumulative effects of repetitive heading may cause sub-concussive injury with accompanying effects on brain and behavior. The current study aimed to prospectively investigate the effects of repetitive, intentional heading in soccer practice on brain structure and cognitive function, using a within-subjects design.

Methods

Participants included 10 soccer players (mean age 20.09 years ± 2.88) who were examined immediately pre- and post-heading practice. An accelerometer was used to measure the force of the impact during soccer heading. Magnetic resonance imaging data were acquired on a 3 T GE Scanner with diffusion tensor imaging. Diffusion tensor imaging analyses were completed using functional magnetic resonance imaging of the brain software library’s Tract-Based Spatial Statistics to examine changes in both fractional anisotropy and mean diffusivity due to heading the soccer ball. Behavioral measures were also completed pre- and post-soccer heading and included the Sport Concussion Assessment Tool and three short-computerized executive function tasks; R studio was used to compare behavioral data within subjects.

Results

Accelerometer data revealed that none of the heading impacts were >10 g. At this level of impact, there were no significant pre–post heading differences in either fractional anisotropy or mean diffusivity. Additionally, aside from minimal practice effects, there were no significant differences in Sport Concussion Assessment Tool scores and no significant differences in the performance of the three executive function tasks pre–post heading.

Conclusions

The results provide initial evidence that repetitive heading in soccer practice, at a g force of 10, does not cause changes in brain structure or executive function. Future research should investigate heading in the context of games and with a greater sample size that would allow for sex-based comparisons.

Chronic Traumatic Encephalopathy and Neurodegeneration in Contact Sports and American Football

Chronic traumatic encephalopathy (CTE) is a neurodegenerative disease characterized by the presence of abnormally phosphorylated tau protein in the depths of one or more cortical sulci. Controversy over the risk of CTE and neurologic disorders later in life among contact sport athletes has taken hold in the public spotlight, most notably in American football. Players, parents, coaches, and legislators have taken action based on the commonly held notion that contact sports invariably lead to neurodegenerative disorders. However, to fully understand the science behind this assumed association, a critical appraisal of the evidence is warranted. With regards to CTE in sports, the objectives of the current report are to: 1) describe the history of CTE, 2) review current CTE definitions, 3) critically evaluate the empiric data, divided into all contact sports and exclusively American football, and 4) summarize notable themes for future research.

Self-reported head injury symptoms exacerbated in those with previous concussions following an acute bout of purposeful soccer heading

Rates of concussion in soccer are high, especially in female players. The primary aim of this study was to examine differences in self-reported concussion-related symptoms (CRS), balance (BESS), and neurocognitive performance (ImPACT) following an acute bout of soccer heading in a group of female collegiate players with and without a history of concussion. Eighty-seven players with 0 to 3+ previous concussions participated. The measurement variables were assessed before and after heading sessions; including one linear and one rotational bout. Players with concussion histories reported more CRS than their non-concussed teammates both before and after the heading sessions. Balance and neurocognitive scores were generally unaffected. This finding should heighten our awareness to carefully monitor soccer players who have experienced concussions and be aware that they may develop concussion-like symptoms, especially after acute bouts of heading either during practice or in matches. The long-term implications of this finding remain unknown.

No Evidence of Association Between Soccer Heading and Cognitive Performance in Professional Soccer Players: Cross-Sectional Results

Although the scientific community has focused on the effects of concussions in contact sports, the role of subconcussive impacts, as it can occur during soccer heading, has recently gained attention, considering that it may represent an additional mechanism of cumulative brain injury. The aim of this study is to investigate the effects of soccer heading on cognitive functioning in active professional soccer players. Male soccer players (n = 44), from two soccer teams that play in the Brazilian A Series Championship, and non-athletes (n = 47), comparable in age and education, were submitted to cognitive assessment, consisting of computerized and conventional neuropsychological testing (Neupsilin battery). In the computerized cognitive assessment, soccer players performed better than controls on reaction time measures in general motor coordination, executive functioning and memory tests, and on accuracy measures in executive functioning tests. There were no significant differences between groups on the Neupsilin battery. A comparison between two sub-groups of soccer players, based on the self-reported number of headings, did not show significant differences on tests performance. No significant correlations were found between an estimate of exposure to heading during professional soccer career and cognitive performance. Our data demonstrate no evidence of cognitive impairment in soccer players, compared to non-athletes, and no association between heading exposure and performance on neuropsychological tests. Longitudinal investigations, including neuroimaging assessment, will help to clarify whether soccer heading may be associated with brain injury and cognitive dysfunction.

Head Injury in Soccer: From Science to the Field; summary of the head injury summit held in April 2017 in New York City, New York

There has been an increased focus and awareness of head injury and sport-related concussion (SRC) across all sports from the medical and scientific communities, sports organisations, legislators, the media and the general population. Soccer, in particular, has been a focus of attention due to the popularity of the game, the frequency of SRC and the hypothesised effects of repetitive heading of the ball. Major League Soccer, US Soccer and the National Women’s Soccer League jointly hosted a conference entitled, ‘Head Injury in Soccer: From Science to the Field’, on 21–22 April 2017 in New York City, New York. The mission of this conference was to identify, discuss and disseminate evidence-based science related to the findings and conclusions of the fifth International Conference on Concussion in Sport held by the Concussion in Sport Group and apply them to the sport of soccer. In addition, we reviewed information regarding the epidemiology and mechanism of head injuries in soccer at all levels of play, data regarding the biomechanics and effects of repetitive head impacts and other soccer-specific considerations. We discussed how to release the information raised during the summit to key stakeholders including athletes, parents, coaches and healthcare providers. We identified future areas for research and collaboration to enhance the health and safety of soccer (football) players.

Assessment of executive function using the Tinkertoy test

The Tinkertoy test (TTT) has often been used to assess executive function. Despite its clinical importance, there are few published normative data for it. Thus, the primary aim of this study was to fill this gap. Moreover, as there exists a sex difference in many cognitive abilities and neuropsychological tests, a secondary aim was to examine whether sex influences TTT performance. We administered the TTT to 25 healthy men and 25 healthy women whose average age was 28 years. Performances were scored based upon Lezak's (1982) original TTT criteria. On average, our participants used 43 pieces to complete their construction (SD=8), with a range of 21-50, and their complexity scores ranged from 7 to 12, with a mean score of 9.68 (SD=1.35). Overall performance did not differ based on sex; yet, when examining individual scoring criteria, we found that men scored significantly higher on the symmetry measure. Efforts towards the development of adequate normative data for the TTT and different tests of executive functioning are crucial to neuropsychologists' and other healthcare providers' ability to reliably diagnose and treat disorders of cognition that affect executive function. The present data go some way towards enhancing the utility of the TTT.

May Heading in Soccer Result in Traumatic Brain Injury? A Review of Literature

Background:

Globally, soccer is the most popular team sport, unifying many fans all around the world. The epidemiological studies so far have confirmed that head playing and hitting the ball with head may cause minor head injuries, which exert their effects in a cumulative way.

Methods:

Literature search for this review was conducted and data about traumatic brain injury collected from various sources.

Results:

The consequences of head injury are evident as chronic changes in cognition, including disturbances in concentration and slowing of mental and physical agility.

Conclusion:

Various recommendations have been issued for the prevention of chronic negative cumulative effects of soccer ball head playing. In addition, the professional soccer players are also exposed to more intense craniocerebral trauma, such as concussions and contusions. These patients require treatment of skilled sports physicians, neurologists and neurosurgeons and some may need long to return to the sport scene again.

Chronic traumatic encephalopathy in sports: a historical and narrative review

My objectives are to review: 1) a brief history of sport-related concussion (SRC) and chronic traumatic encephalopathy (CTE), 2) the evolution of CTE in American professional football, 3) the data regarding SRC/CTE as they relate to depression and suicide, 4) the data on the neurocognitive effects of subconcussion/repetitive head trauma (with emphases on heading the ball in soccer and early exposure to football), 5) the evidence related to SRC and neurodegenerative diseases, 6) the published studies of CTE, 7) the NINDS neuropathological criteria for CTE, 8) public beliefs about SRC/CTE, and 9) the scientific questions regarding CTE.

Recent and Long-Term Soccer Heading Exposure Is Differentially Associated With Neuropsychological Function in Amateur Players

OBJECTIVES

The present study examined the relative contribution of recent or long-term heading to neuropsychological function in amateur adult soccer players.

PARTICIPANTS AND METHODS

Soccer players completed a baseline questionnaire (HeadCount-12m) to ascertain heading during the prior 12 months (long-term heading, LTH) and an online questionnaire (HeadCount-2w) every 3 months to ascertain heading during the prior 2 weeks (recent heading, RH). Cogstate, a battery of six neuropsychological tests, was administered to assess neuropsychological function. Generalized estimating equations were used to test if LTH or RH was associated with neuropsychological function while accounting for the role of recognized concussion.

RESULTS

A total of 311 soccer players completed 630 HeadCount-2w. Participants had an average age of 26 years. Participants headed the ball a median of 611 times/year (mean=1,384.03) and 9.50 times/2 weeks (mean=34.17). High levels of RH were significantly associated with reduced performance on a task of psychomotor speed (p=.02), while high levels of LTH were significantly associated with poorer performance on tasks of verbal learning (p=.03) and verbal memory (p=.04). Significantly better attention (p=.02) was detectable at moderately high levels of RH, but not at the highest level of RH. One hundred and seven (34.4%) participants reported a lifetime history of concussion, but this was not related to neuropsychological function and did not modify the association of RH or LTH with neuropsychological function.

CONCLUSION

High levels of both RH and LTH were associated with poorer neuropsychological function, but on different domains. The clinical manifestations following repetitive exposure to heading could change with chronicity of exposure. (JINS, 2018, 24, 147-155).

Comparing fMRI activation during smooth pursuit eye movements among contact sport athletes, non-contact sport athletes, and non-athletes

Objectives

Though sub-concussive impacts are common during contact sports, there is little consensus whether repeat blows affect brain function. Using a "lifetime exposure" rather than acute exposure approach, we examined oculomotor performance and brain activation among collegiate football players and two control groups. Our analysis examined whether there are group differences in eye movement behavioral performance and in brain activation during smooth pursuit.

Methods

Data from 21 off-season Division I football "starters" were compared with a) 19 collegiate cross-country runners, and b) 11 non-athlete college students who were SES matched to the football player group (total N = 51). Visual smooth pursuit was performed while undergoing fMRI imaging via a 3 Tesla scanner. Smooth pursuit eye movements to three stimulus difficulty levels were measured with regard to RMS error, gain, and lag.

Results

No meaningful differences were found for any of the standard analyses used to assess smooth pursuit eye movements. For fMRI, greater activation was seen in the oculomotor region of the cerebellar vermis and areas of the FEF for football players as compared to either control group, who did not differ on any measure.

Conclusion

Greater cerebellar activity among football players while performing an oculomotor task could indicate that they are working harder to compensate for some subtle, long-term subconcussive deficits. Alternatively, top athletes in a sport requiring high visual motor skill could have more of their cerebellum and FEF devoted to oculomotor task performance regardless of subconcussive history. Overall, these results provide little firm support for an effect of accumulated subconcussion exposure on brain function.

Investigating Cognitive Performance Deficits in Male and Female Soccer Players after a 4-week Heading- Training Programme: A Controlled Study

This experimental study with a controlled pre-test and post-test group design investigated the possible effects of four sessions of heading training on cognitive performance. A total of 118 participants (mean age of 22.25 years) were assigned to one of the three following groups: a heading-training group, a passing-training group and a waiting control group. The participants completed a cognitive test battery of attention (D2-test), working memory (Paced Auditory Serial Addition Task, PASAT-2) and visual spatial intelligence (Mental Rotation Test) tests before, immediately after the second training session and one week after the fourth training session. There were no between-group differences in cognitive performance after the second or the fourth heading training sessions. However, within the heading-training group, women complained more of headaches than men after the fourth training session. These results build on the results from the study of Rieder and Jansen (2011) that showed no neuropsychological consequences after one heading session, showing no cumulative effects of repeat heading.

Quantifying Head Impact Exposure in Collegiate Women's Soccer

OBJECTIVE

The aim of this study was to quantify head impact exposure for a collegiate women's soccer team over the course of the 2014 season.

DESIGN

Observational and prospective study.

SETTING

Virginia Tech women's soccer games and practices.

PARTICIPANTS

Twenty-six collegiate level women's soccer players with a mean player age of 19 ± 1.

INTERVENTIONS

Participating players were instrumented with head impact sensors for biomechanical analysis. Video recordings of each event were used to manually verify each impact sustained.

MAIN OUTCOME MEASURES

Head impact counts by player position and impact situation.

RESULTS

The sensors collected data from a total of 17 865 accelerative events, 8999 of which were classified as head impacts. Of these, a total of 1703 impacts were positively identified (19% of total real impacts recorded by sensor), 90% of which were associated with heading the ball. The average number of impacts per player per practice or game was 1.86 ± 1.42. Exposure to head impact varied by player position.

CONCLUSIONS

Head impact exposure was quantified through 2 different methods, which illustrated the challenges associated with autonomously collecting acceleration data with head impact sensors. Users of head impact data must exercise caution when interpreting on-field head impact sensor data.

The independent influence of concussive and sub-concussive impacts on soccer players' neurophysiological and neuropsychological function

Accumulating research demonstrates that repetitive sub-concussive impacts can alter the structure, function and connectivity of the brain. However, the functional significance of these alterations as well as the independent contribution of concussive and sub-concussive impacts to neurophysiological and neuropsychological health are unclear. Accordingly, we compared the neurophysiological and neuropsychological function of contact athletes with (concussion group) and without (sub-concussion group) a history of concussion, to non-contact athletes. We evaluated event-related brain potentials (ERPs) elicited during an oddball task and performance on a targeted battery of neuropsychological tasks. Athletes in the sub-concussion and concussion groups exhibited similar amplitude reductions in the ERP indices of attentional resource allocation (P3b) and attentional orienting (P3a) relative to non-contact athletes. However, only athletes in the concussion group exhibited reduced amplitude in the ERP index of perceptual attention (N1). Athletes in the sub-concussion and concussion groups also exhibited deficits in memory recall relative to non-contact athletes, but athletes in the concussion group also exhibited significantly more recall errors than athletes in the sub-concussion group. Additionally, only athletes in the concussion group exhibited response delays during the oddball task. The current findings suggest that sub-concussive impacts are associated with alterations in the neurophysiological and neuropsychological indices of essential cognitive functions, albeit to a lesser degree than the combination of sub-concussive and concussive impacts.

Validation and calibration of HeadCount, a self-report measure for quantifying heading exposure in soccer players

The long-term effects of repetitive head impacts due to heading are an area of increasing concern, and exposure must be accurately measured; however, the validity of self-report of cumulative soccer heading is not known. In order to validate HeadCount, a 2-week recall questionnaire, the number of player-reported headers was compared to the number of headers observed by trained raters for a men's and a women's collegiate soccer teams during an entire season of competitive play using Spearman's correlations and intraclass correlation coefficients (ICCs), and calibrated using a generalized estimating equation. The average Spearman's rho was 0.85 for men and 0.79 for women. The average ICC was 0.75 in men and 0.38 in women. The calibration analysis demonstrated that men tend to report heading accurately while women tend to overestimate. HeadCount is a valid instrument for tracking heading behaviour, but may have to be calibrated in women.

Biomechanical Perspectives on Concussion in Sport

Concussions can occur in any sport. Often, clinical and biomechanical research efforts are disconnected. This review paper analyzes current concussion issues in sports from a biomechanical perspective and is geared toward Sports Med professionals. Overarching themes of this review include the biomechanics of the brain during head impact, role of protective equipment, potential population-based differences in concussion tolerance, potential intervention strategies to reduce the incidence of injury, and common biomechanical misconceptions.

Vestibular Dysfunction after Subconcussive Head Impact

Current thinking views mild head impact (i.e., subconcussion) as an underrecognized phenomenon that has the ability to cause significant current and future detrimental neurological effects. Repeated mild impacts to the head, however, often display no observable behavioral deficits based on standard clinical tests, which may lack sensitivity. The current study investigates the effects of subconcussive impacts from soccer heading with innovative measures of vestibular function and walking stability in a pre- 0-2 h, post- 24 h post-heading repeated measures design. The heading group (n = 10) executed 10 headers with soccer balls projected at a velocity of 25 mph (11.2 m/sec) over 10 min. Subjects were evaluated 24 h before, immediately after, and 24 h after soccer heading with: the modified Balance Error Scoring System (mBESS); a walking stability task with visual feedback of trunk movement; and galvanic vestibular stimulation (GVS) while standing with eyes closed on foam. A control group (n = 10) followed the same protocol with no heading. The results showed significant decrease in trunk angle, leg angle gain, and center of mass gain relative to GVS for the heading group compared with controls. Medial-lateral trunk orientation displacement and velocity during treadmill walking increased immediately after mild head impact for the heading group compared with controls. Controls showed an improvement in mBESS scores over time, indicating a learning effect, which was not observed with the heading group. These results suggest that mild head impact leads to a transient dysfunction in vestibular processing, which deters walking stability during task performance.

Head and neck injuries in football (soccer)

The incidence for concussions in football (soccer) is equivalent to other contact sports such as American football and ice hockey. The risk of concussion is increased in goalkeepers, females and perhaps young players. Head to head contact between athletes is the most common mechanism for concussion, while heading does not appear to be a frequent cause. Research is providing evidence that neck muscle development and protective headgear may play a role in the prevention of concussions. The presence and pathophysiology of a chronic encephalopathy secondary to a cumulative subconcussive blows obtained in football is still controversial. Neck injuries are not as common as head injuries and are not frequently reported in the literature. The biomechanics of neck injuries are different between children and adults which may account for the different types of injuries in these populations. Spinal cord injuries are rarely seen in football and are usually associated with major fractures/dislocations.

Effects of Soccer Heading on Brain Structure and Function

Soccer is the most popular sport in the world, with more than 265 million players worldwide, including professional and amateur ones. Soccer is unique in comparison to other sports, as it is the only sport in which participants purposely use their head to hit the ball. Heading is considered as an offensive or defensive move whereby the player's unprotected head is used to deliberately impact the ball and direct it during play. A soccer player can be subjected to an average of 6-12 incidents of heading the ball per competitive game, where the ball reaches high velocities. Moreover, in practice sessions, heading training, which involves heading the ball repeatedly at low velocities, is common. Although the scientific community, as well as the media, has focused on the effects of concussions in contact sports, the role of subconcussive impacts, as it can occur during heading, has recently gained attention, considering that it may represent an additional mechanism of cumulative brain injury. The purpose of this study is to review the existing literature regarding the effects of soccer heading on brain structure and function. Only in the last years, some investigations have addressed the impact of heading on brain structure, by using neuroimaging techniques. Similarly, there have been some recent studies investigating biochemical markers of brain injury in soccer players. There is evidence of association between heading and abnormal brain structure, but the data are still preliminary. Also, some studies have suggested that subconcussive head impacts, as heading, could cause cognitive impairment, whereas others have not corroborated this finding. Questions persist as to whether or not heading is deleterious to cognitive functioning. Further studies, especially with longitudinal designs, are needed to clarify the clinical significance of heading as a cause of brain injury and to identify risk factors. Such investigations might contribute to the establishment of safety guidelines that could help to minimize the risk of possible adverse effects of soccer on brain structure and function.

Pediatricians' knowledge of current sports concussion legislation and guidelines and comfort with sports concussion management: a cross-sectional study

BACKGROUND

Sports-related concussions disproportionately affect young athletes. The primary objective of our study was to determine Illinois pediatricians' level of familiarity with state concussion legislation and with published consensus guidelines for sports concussion diagnosis and treatment. We also sought to determine pediatricians' knowledge regarding concussion management and comfort treating sports concussion patients.

METHODS

This was a cross-sectional survey of pediatrician members of the Illinois Chapter of the American Academy of Pediatrics.

RESULTS

Few general pediatricians (26.6%, n = 42) were "very familiar" or "somewhat familiar" with the recently passed Illinois state concussion legislation. Only 14.6% (n = 23) of general pediatrician respondents use concussion consensus guidelines in their practice. Pediatricians were generally very knowledgeable about concussions; only 5 out of 19 knowledge-based items were answered incorrectly by more than 25% of the study participants.

CONCLUSIONS

General pediatricians are knowledgeable about concussions but most are not well aware of state concussion legislation and concussion consensus guidelines.

Concussions and heading in soccer: a review of the evidence of incidence, mechanisms, biomarkers and neurocognitive outcomes

BACKGROUND

Soccer is currently the most popular and fastest-growing sport worldwide. Similar to many sports, soccer carries an inherent risk of injury, including concussion. Soccer is also unique in the use of 'heading'. The present paper provides a comprehensive review of the research examining the incidence, mechanisms, biomarkers of injury and neurocognitive outcomes of concussions and heading in soccer.

METHODS

Seven databases were searched for articles from 1806 to 24 May 2013. Articles obtained by the electronic search were reviewed for relevance, with 229 selected for review. Ultimately, 49 articles met criteria for inclusion in the present review.

RESULTS

Female soccer players have a higher incidence of concussions than males. The most frequent injury mechanism is player-to-player contact for both genders. Few studies examined the effects of concussion in soccer players; however, neurocognitive outcomes were similar to those reported in the larger sport concussion literature, while the effect of heading is less clear.

CONCLUSION

Despite variation in research designs and study characteristics, the outcomes of concussions in soccer align with the greater concussion literature. This review makes recommendations for future research to increase standardization of research for improved understanding of concussions in soccer as well as the effects of heading.

Neck strength imbalance correlates with increased head acceleration in soccer heading

Background:

Soccer heading is using the head to directly contact the ball, often to advance the ball down the field or score. It is a skill fundamental to the game, yet it has come under scrutiny. Repeated subclinical effects of heading may compound over time, resulting in neurologic deficits. Greater head accelerations are linked to brain injury. Developing an understanding of how the neck muscles help stabilize and reduce head acceleration during impact may help prevent brain injury.

Hypothesis:

Neck strength imbalance correlates to increasing head acceleration during impact while heading a soccer ball.

Study Design:

Observational laboratory investigation.

Methods:

Sixteen Division I and II collegiate soccer players headed a ball in a controlled indoor laboratory setting while player motions were recorded by a 14-camera Vicon MX motion capture system. Neck flexor and extensor strength of each player was measured using a spring-type clinical dynamometer.

Results:

Players were served soccer balls by hand at a mean velocity of 4.29 m/s (±0.74 m/s). Players returned the ball to the server using a heading maneuver at a mean velocity of 5.48 m/s (±1.18 m/s). Mean neck strength difference was positively correlated with angular head acceleration (rho = 0.497; P = 0.05), with a trend toward significance for linear head acceleration (rho = 0.485; P = 0.057).

Conclusion:

This study suggests that symmetrical strength in neck flexors and extensors reduces head acceleration experienced during low-velocity heading in experienced collegiate players.

Clinical Relevance:

Balanced neck strength may reduce head acceleration cumulative subclinical injury. Since neck strength is a measureable and amenable strength training intervention, this may represent a modifiable intrinsic risk factor for injury.

Concussions in soccer: a current understanding

OBJECTIVE

Traumatic brain injury (TBI) is a significant public health problem in the United States, with approximately 1.5-2 million TBIs occurring each year. However, it is believed that these figures underestimate the true toll of TBI. Soccer is the most popular sport in the world and has a following of millions in the United States. Soccer is a sport not traditionally identified as high-risk for concussions, yet several studies have shown that concussion rates in soccer are comparable to, and often exceed those of, other contact sports. As many as 22% of all soccer injuries are concussions.

METHODS

Soccer is a sport not traditionally identified as high risk for concussions, yet several studies have shown that concussion rates in soccer are comparable to, and often exceed those of, other contact sports. As many as 22% of all soccer injuries are concussions. Head injury during soccer is usually the result of either "direct contact" or contact with the ball while "heading" the ball. Relationships between the number of headers sustained in a single season and the degree of cognitive impairment (attention and visual/verbal memory) have been demonstrated. It is also likely that multiple concussions may cause cumulative neuropsychologic impairment in soccer players.

RESULTS

Although our understanding of risk factors for sports-related concussions is far from complete, there is great potential for prevention in sports-related concussions. Several measures must be taken to avert the development of concussions in soccer and, when they take place, reduce their effects. These include the development and testing of effective equipment during play, the maintenance of regulatory standards for all such equipment, educating young athletes on the safe and appropriate techniques used during play, and strict adherence to the rules of competition.

CONCLUSIONS

In spite of such preventive measures, concussions in soccer will continue to occur. Considering the frequency of concussions in soccer, the serious sequelae of these concussions, and because almost half of concussed soccer players were noncompliant with recommended American Academy of Neurology return-to-play guidelines, further measures must be taken to protect players, in addition to understanding those criteria that result in removing an injured player from competition and the steps by which to safely return an athlete to competition after injury.

Gender differences in self reported long term outcomes following moderate to severe traumatic brain injury

BACKGROUND

The majority of research on health outcomes after a traumatic brain injury is focused on male participants. Information examining gender differences in health outcomes post traumatic brain injury is limited. The purpose of this study was to investigate gender differences in symptoms reported after a traumatic brain injury and to examine the degree to which these symptoms are problematic in daily functioning.

METHODS

This is a secondary data analysis of a retrospective cohort study of 306 individuals who sustained a moderate to severe traumatic brain injury 8 to 24 years ago. Data were collected using the Problem Checklist (PCL) from the Head Injury Family Interview (HIFI). Using Bonferroni correction, group differences between women and men were explored using Chi-square and Wilcoxon analysis.

RESULTS

Chi-square analysis by gender revealed that significantly more men reported difficulty setting realistic goals and restlessness whereas significantly more women reported headaches, dizziness and loss of confidence. Wilcoxon analysis by gender revealed that men reported sensitivity to noise and sleep disturbances as significantly more problematic than women, whereas for women, lack of initiative and needing supervision were significantly more problematic in daily functioning.

CONCLUSION

This study provides insight into gender differences on outcomes after traumatic brain injury. There are significant differences between problems reported by men compared to women. This insight may facilitate health service planners and clinicians when developing programs for individuals with brain injury.

Injuries in youth soccer

Injury rates in youth soccer, known as football outside the United States, are higher than in many other contact/collision sports and have greater relative numbers in younger, preadolescent players. With regard to musculoskeletal injuries, young females tend to suffer more knee injuries, and young males suffer more ankle injuries. Concussions are fairly prevalent in soccer as a result of contact/collision rather than purposeful attempts at heading the ball. Appropriate rule enforcement and emphasis on safe play can reduce the risk of soccer-related injuries. This report serves as a basis for encouraging safe participation in soccer for children and adolescents.

Sport-related concussion

Sport-related concussion is a common injury in children and adolescents. Athletes seldom report concussive symptoms, which makes the diagnosis a challenge. The management of sport-related concussion has changed significantly over the last several years. The previously used grading systems and return-to-play guidelines have been abandoned in favor of more individualized assessment and management. Neuropsychological testing is being used more frequently to assist in management. After recovery, it is recommended that an athlete's return-to-play progress in a gradual, stepwise fashion while being monitored by a health care provider. Proper assessment and management of a sport-related concussion is crucial, because repeat concussions can result in decreased neurocognitive functioning, increased symptomatology, and, at times, catastrophic outcomes.

Examining the relationship between purposeful heading in soccer and computerized neuropsychological test performance

The purpose of this study was to determine if a relationship exists between purposeful heading in soccer and neuropsychological test performance. Automated Neuropsychological Assessment Metrics throughput scores were derived on seven subset variables that measure a variety of neurocognitive abilities. Simple Spearman's rank correlations were calculated between headers per game (HPG) and the criterion variables. Interestingly, math processing speed (Spearman's rho = .160) and continuous performance test #2 (rho = .124) had small but significant correlations; both showed improvement in performance pre- to postseason. There were no significant correlations between HPG and the other five variables. This study found no detrimental relationship between the number of purposeful headers and the neurocognitive measures in this population.

Purposeful heading during a season does not influence cognitive function or balance in female soccer players

Soccer participation, especially among females, is growing in popularity in the United States. Purposeful heading, an important soccer skill, has recently been scrutinized for safety reasons. The purpose of this study was to determine whether there was a relationship between purposeful heading and scores on cognitive function and balance in high school and collegiate female soccer players. Prior to and following the soccer season, all players and members of the control group were given a battery of neuropsychological and balance tests. There were no significant correlations found between the total number of game headers and performance on either balance or neuropsychological testing.Differences were noted in adjusted balance scores postseason between the collegiate players and the other two groups.However, no differences were revealed in neurocognitive performance between the three groups.

Gender differences in executive functions following traumatic brain injury

The present study used the National Institute on Disability Rehabilitation and Research (NIDRR) funded Traumatic Brain Injury Model Systems (TBIMS) database to examine the effect of gender on presentation of executive dysfunction following traumatic brain injury (TBI) and variables that might impact the course and degree of recovery. The Wisconsin Card Sort Test (WCST) was chosen as a measure of executive function which has good credentials without reports of gender effects. Female subjects performed significantly better on the WCST than male subjects as shown by analyses of variance on scores of 1,331 patients for Categories Achieved (means for females = 4.09, males = 3.67, p = .003) and Perseverative Responses (means for females = 32.17, males = 36.42, p = .003). Outperformance by females was also noted in additional ANOVAs examining the interaction of education and gender, and ethnicity and gender in relation to Categories Achieved (p < .01), and for ethnicity and gender in relation to Perseverative Responses (p < .01). A multiple logistic regression revealed that gender, minority status, education level, history of illicit drug use, cause of injury, and length of coma each contributed uniquely to predicting Categories Achieved on the WCST. Simple logistic regression analyses showed that, of these variables, gender and cause of injury (violent vs. non-violent) were the strongest predictors. In contrast, when examining Perseverative Responses, regression analyses found gender, minority status and length of coma predicted impairment. Simple logistic regression analyses showed that, of these three variables, gender and minority status were most robust in predicting impaired Perseverative Responses scores. Implications of these findings are discussed and recommendations for further research are offered.

Neuropsychological impairment as a consequence of football (soccer) play and football heading: A preliminary analysis and report on school students (13–16 years)

Footballers run the risk of incurring mild head injury from a variety of sources, including the intentional use of the head to play the ball, known as heading. This paper presents a preliminary exploratory analysis of data collected to examine whether cumulative incidence of mild head injury, or cumulative heading frequency, are related to neuropsychological functioning in male adolescent footballers. In a quasi-experimental cross-sectional design, neuropsychological test scores of school team footballers were compared with those of similarly aged rugby players and noncontact sport players. Cumulative mild head injury incidence was estimated using self-reports, and cumulative heading was estimated using a combination of observation and self-reports. No participants had sustained a head injury within 3 months of testing. There was no relationship between head injury and neuropsychological performance, and there were no decrements in either the footballers or the rugby players in comparison with the noncontact sport players. Within the footballers, cumulative heading did not predict any of the neuropsychological test scores. These findings indicate the absence of neuropsychological impairment arising due to cumulative mild head injury incidence, or cumulative heading. Although these null findings may be reassuring to players, parents, and football organizers, we stress that they are preliminary. Further data is being collected from the same populations to provide more reliable effect estimates.

Repeat Mild Traumatic Brain Injury

Determining when it is safe for an athlete to return to play (RTP) after concussion is one of the most difficult decisions facing the team physician. There is significant variability in the evaluation and management of mild traumatic brain injury (mTBI). In the past decade, a tremendous amount of sport-specific research has improved our understanding of mTBI. The advent of neuro-psychologic (NP) testing batteries designed to assess concussive injury has improved the assessment of cognitive dysfunction that occurs in the absence of structural brain abnormalities. The severity of injury is determined by the nature, burden, and duration of symptoms. Athletes must be asymptomatic and have a normal neurologic and cognitive evaluation prior to RTP. Several factors aid in making the RTP decision, including age, the severity of injury, and history of prior mTBIs. Given the potential complications of mTBI, the RTP decision must be made using a thoughtful, individualized process.

No cumulative effects for one or two previous concussions

BACKGROUND

Sports medicine clinicians and the general public are interested in the possible cumulative effects of concussion.

OBJECTIVE

To examine whether athletes with a history of one or two previous concussions differed in their preseason neuropsychological test performances or symptom reporting.

METHOD

Participants were 867 male high school and university amateur athletes who completed preseason testing with ImPACT version 2.0. They were sorted into three groups on the basis of number of previous concussions. There were 664 athletes with no previous concussions, 149 with one previous concussion, and 54 with two previous concussions. Multivariate analysis of variance was conducted using the verbal memory, visual memory, reaction time, processing speed, and postconcussion symptom composite scores as dependent variables and group membership as the independent variable.

RESULTS

There was no significant multivariate effect, nor were there any significant main effects for individual scores. There was no measurable effect of one or two previous concussions on athletes' preseason neuropsychological test performance or symptom reporting.

CONCLUSION

If there is a cumulative effect of one or two previous concussions, it is very small and undetectable using this methodology.

Effectiveness of headgear in football

OBJECTIVES

Commercial headgear is currently being used by football players of all ages and skill levels to provide protection from heading and direct impact. The clinical and biomechanical effectiveness of the headgear in attenuating these types of impact is not well defined or understood. This study was conducted to determine whether football headgear has an effect on head impact responses.

METHODS

Controlled laboratory tests were conducted with a human volunteer and surrogate head/neck system. The impact attenuation of three commercial headgears during ball impact speeds of 6-30 m/s and in head to head contact with a closing speed of 2-5 m/s was quantified. The human subject, instrumented to measure linear and angular head accelerations, was exposed to low severity impacts during heading in the unprotected and protected states. High severity heading contact and head to head impacts were studied with a biofidelic surrogate headform instrumented to measure linear and angular head responses. Subject and surrogate responses were compared with published injury assessment functions associated with mild traumatic brain injury (MTBI).

RESULTS

For ball impacts, none of the headgear provided attenuation over the full range of impact speeds. Head responses with or without headgear were not significantly different (p>0.05) and remained well below levels associated with MTBI. In head to head impact tests the headgear provided an overall 33% reduction in impact response.

CONCLUSION

The football headgear models tested did not provide benefit during ball impact. This is probably because of the large amount of ball deformation relative to headband thickness. However, the headgear provided measurable benefit during head to head impacts.

A six year prospective study of the incidence and causes of head and neck injuries in international football

OBJECTIVE

To identify those risk factors that have the greatest impact on the incidence of head and neck injuries in international football.

METHOD

A case-control study of players sustaining head and neck injuries during 20 FIFA tournaments (men and women) from 1998 to 2004. Video recordings of incidents were used to identify a range of parameters associated with the incidents. Team physicians provided medical reports describing the nature of each injury. chi2 tests (p< or =0.01) and 95% confidence intervals were used to assess differences in distribution and incidence of injury, respectively.

RESULTS

In total, 248 head and neck injuries were recorded of which 163 were identified and analysed on video sequences. The commonest injuries were contusions (53%), lacerations (20%), and concussions (11%). The incidence of all head and neck injuries was 12.5/1000 player hours (men 12.8, women 11.5) and 3.7 for lost-time injuries (men 3.5, women 4.1). The commonest causes of injury involved aerial challenges (55%) and the use of the upper extremity (33%) or head (30%). The unfair use of the upper extremity was significantly more likely to cause an injury than any other player action. Only one injury (a neck muscle strain) occurred as a result of heading the ball throughout the 20 tournaments equivalent to 0.05 injuries/1000 player hours.

CONCLUSIONS

Players' actions most likely to cause a head or neck injury were the use of the upper extremity or the head but in the majority of cases these challenges were deemed to be fair and within the laws of the game.

Heading in football. Part 1: development of biomechanical methods to investigate head response

OBJECTIVES

There has been growing controversy regarding long term effects of repeated low severity head impacts such as when heading a football. However, there are few scientific data substantiating these concerns in terms of the biomechanical head response to impact. The present study aimed to develop a research methodology to investigate the biomechanical response of human subjects during intentional heading and identify strategies for reducing head impact severity.

METHODS

A controlled laboratory study was carried out with seven active football players, aged 20-23 and of average stature and weight. The subjects were fitted with photographic targets for kinematic analysis and instrumented to measure head linear/angular accelerations and neck muscle activity. Balls were delivered at two speeds (6 m/s and 8 m/s) as the subjects executed several specific forward heading manoeuvres in the standing position. Heading speeds up to 11 m/s were seen when the head closing speed was considered. One subject demonstrating averaged flexion-extension muscle activity phased with head acceleration data and upper torso kinematics was used to validate a biofidelic 50th percentile human model with a detailed head and neck. The model was exercised under ball incoming speeds of 6-7 m/s with parameter variations including torso/head alignment, neck muscle tensing, and follow through. The model output was subsequently compared with additional laboratory tests with football players (n = 3). Additional heading scenarios were investigated including follow through, non-active ball impact, and non-contact events. Subject and model head responses were evaluated with peak linear and rotational accelerations and maximum incremental head impact power.

RESULTS

Modelling of neck muscle tensing predicted lower head accelerations and higher neck loads whereas volunteer head acceleration reductions were not consistent. Modelling of head-torso alignment predicted a modest reduction in volunteer head accelerations. Exaggerated follow through while heading reduced volunteer head accelerations modestly.

CONCLUSION

Biomechanical methods were developed to measure head impact response. Changing the biomechanics of currently accepted heading techniques will have inconsistent benefits towards the reduction of head loading. Furthermore, mathematical modelling suggested an increased risk of neck loads with one alternative technique. No consistent recommendations can be made on the basis of the current study for altering heading techniques to reduce impact severity.