Systematic review and meta-analysis of sex-based differences for concussion incidence in soccer

The incidence and characteristics of heading in the 2019 FIFA Women's World Cup™

INTRODUCTION

To quantify the incidence and characteristics of purposeful heading and other head impacts in professional women's football at the 2019 FIFA Women's World Cup™.

METHODS

This cross-sectional cohort study analysed purposeful headers (uncontested and contested) and their characteristics (e.g. playing position, match situation, field location, and distance ball travelled), and other head impact events using video analysis. Total headers and head impact events, and incidence rate (IR) per 1000 match-hours were calculated for countries, positions, and other characteristics, such as location on the pitch.

RESULTS

Purposeful headers accounted for 76% of all coded events (uncontested: 71%; contested: 29%), followed by attempted headers (21%), unintentional ball-head impacts (2%), and other head impacts (1%). Headers ranged from 0 to 22 per player, per match with a mean of 4.8 [±1.2]. Of all field positions, centrebacks had the highest heading rates and wingers the lowest. Strikers performed significantly more contested headers than any other position, and significantly less uncontested headers. Most headers occurred in the middle third (48%), from free game play (72%) and from long balls (>20 m) (68%).

CONCLUSION

The findings of this study could assist the development of player heading risk profiles, sex-specific heading guidelines, and coaching practices.

Exploring Sex-Based Variations in Head Kinematics During Soccer Heading

While studies indicate that females experience a higher concussion risk and more severe outcomes in soccer heading compared to males, comprehensive data on the underlying factors contributing to these sex-based differences are lacking. This study investigates the sex differences in the head-to-ball impact kinematics among college-aged soccer headers in a laboratory-controlled setting. Forty subjects (20 females, 20 males) performed ten headers, and impact kinematics, including peak angular acceleration and velocity (PAA, PAV) and peak linear acceleration (PLA), were measured using mouthguards. Video recordings verified impacts and impact locations. Participants' head mass was estimated from their weights. The relationship between head mass and kinematic parameters was analyzed using Pearson correlation. The effects of head mass, sex, and impact location on kinematic parameters were assessed using MANOVA with and without head mass as a covariate. Results showed that head mass, larger in males than females, significantly affects PAA and PLA, the greater the head mass, the lower PAA and PLA. However, head mass has no effect on PAV. Females showed significantly higher PAA and PLA components but no significant differences in PAV. Impact location significantly influenced PAV, showing higher magnitudes for frontal impacts compared to top-front impacts, with no significant effects on PAA and PLA. Our results agree with epidemiological evidence that female soccer players face greater concussion risks than males, which can be attributed to their higher header-induced PAA. Future research could consider interventions like changing ball pressure, using protective headgear, and improving heading techniques to reduce high-magnitude accelerations in females.

Concussion in high school sports: findings from injury surveillance

BACKGROUND

We aimed to examine the epidemiology of concussions within high school (HS) boys' and girls' sports, and to assess the incidence of concussion within HS sports during the timespan inclusive of the COVID-19 pandemic.

METHODS

We analyzed data captured within High School Reporting Information Online (HS RIO) during 2018/19-2022/23. Injury counts, rates (enumerated per 10,000 athlete-exposures (AEs)), and proportions were used to describe injury characteristics by sport, event type, injury mechanism, and injury history. Injury rate ratios (IRR) and accompanying 95% Confidence Intervals (CIs) were used to evaluate differential injury incidence across event types and sports.

RESULTS

A total of 4663 concussions were reported during the study period (Rate = 3.50 per 10,000 AEs). Overall rates were highest in boys' football (8.22 per 10,000 AEs) and girls' soccer (6.11 per 10,000 AEs). Among sex-comparable sports, overall concussion rates were higher in girls' sports as compared with boys' sports (IRR = 2.15; 95%CI = [1.94, 2.37]). Concussion rates fluctuated across the study period and were lower during the COVID-19-impacted seasons, as compared with neighboring years.

CONCLUSIONS

Our findings underscore the necessity for continuous surveillance of concussions in HS sports and suggest that concussion incidence in girls' sports warrants targeted attention.

IMPACT

Sport-related concussions are a significant concern, particularly in youth athletics, with changes to concussion management and the impact of the COVID-19 pandemic necessitating a re-evaluation of concussion incidence and management in high school sports. In this surveillance study (2018/19-2022/23), boys' football and girls' soccer had the highest concussion rates, with a decrease in incidence observed during the COVID-19 pandemic as compared with surrounding years. The incidence of concussions in girls' sports requires increased scrutiny, especially due to an overall increase in incidence density observed after an initial decrease during the COVID-19 pandemic.

Pediatric Concussion Injuries in Soccer: Emergency Department Trends in the United States From 2012 to 2023

Background

Because of growing concerns regarding repeated head trauma, in 2016, the United States Soccer Federation (USSF) banned headers for athletes aged ≤10 years and limited athletes aged 11 to 13 years to practicing headers for 30 minutes per week.

Purpose

To assess whether the USSF header policy was associated with fewer soccer-related concussions after the 2015 season.

Study Design

Descriptive epidemiology study.

Methods

A retrospective cohort from the National Electronic Injury Surveillance System database was assessed. Age, sex, and injury type were extracted for all soccer-related emergency department visits between January 1, 2012, and December 31, 2023. Univariate and multiple regression analyses were used to assess concussions as a percentage of all soccer-related injuries based on sex, age group (6-9, 10-13, and 14-17 years), and year. The following time frames were assessed: 2012-2015, 2016-2019, and 2020-2023.

Results

The proportion of concussions decreased from 8.2% of all soccer-related injuries in 2012-2015 to 6.1% in 2020-2023 (P < .01). The relative risk reduction for soccer-related concussions presenting to an emergency department in 2020-2023 compared with 2012-2015 was 25.6%. Overall, the proportion of concussions among 10- to 13-year-old and 14- to 17-year-old players was higher than for 6- to 9-year-old players (6.6% and 8.9% vs 4.9%, respectively; P < .01). Despite having a lower frequency of soccer-related injuries overall, female players had a greater proportion of concussions than male players (9.6% vs 6.2% of all soccer-related injuries; P < .01). In the multiple regression analysis, injuries that occurred in 2020-2023 were associated with lower odds of concussion compared with 2012-2015 (odds ratio [OR], 0.75 [95% CI, 0.69-0.81]). Compared with 6- to 9-year-old and male players, the 10- to 13-year-old (OR, 1.30 [95% CI, 1.16-1.45]), 14- to 17-year-old (OR, 1.79 [95% CI, 1.61-1.99]), and female players (OR, 1.53 [95% CI, 1.43-1.63]) were associated with higher odds of concussion.

Conclusion

A 25.6% reduction in the relative risk of presenting to the emergency department with a soccer-related concussion was found when comparing 2020-2023 (after USSF header policy implementation) with 2012-2015 (before policy implementation). The USSF youth soccer header policy may improve player safety by reducing head impacts in the pediatric population.

Smirl J, Emery CA. Consequences of adolescent sport-related concussion: exploring long-term cardiorespiratory fitness and adiposity

BACKGROUND

Little is known regarding long-term consequences (≥5 years) of sport-related concussion (SRC) sustained during adolescence. Adolescent SRC has been linked to athlete considerations of sport participation and subsequent retirement from sport during this critical developmental period. Prolonged SRC symptoms can reduce ability to perform physical activity, and research suggests inactivity can extend years post-injury. Therefore, SRC may affect long-term physical activity, which may result in decreased cardiorespiratory fitness and increased adiposity.

OBJECTIVES

(1) To examine cardiorespiratory fitness, adiposity and associations with physical activity between three groups: adolescent SRC 5-15 years prior; adolescent musculoskeletal injury (MSK) 5-15 years prior; and individuals who played adolescent sport but were uninjured. (2) To explore whether biological sex-modified relationships assessed by the primary objective.

METHODS

Young adults (16-33 years old) who sustained SRC (n = 54) or MSK (n = 52) during adolescent sport and uninjured individuals (n = 50) were recruited (n = 156) from previous Sport Injury Prevention Research Centre studies and word-of-mouth. Participants completed a cycle-ergometer maximal exertion test, dual-energy X-ray absorptiometry scanning, and wore actigraphs for 1-week post-testing. Outcome measures of cardiorespiratory fitness [peak oxygen consumption (VO2peak[ml/min])] and adiposity [fat mass index (FMI)] were examined in relation to cohort, sex, time since injury, lean mass index and moderate-to-vigorous physical activity [daily MVPA (min)] via multiple linear regression.

RESULTS

In relation to the uninjured cohort, MSK (mean difference = 297.14 ml/min; β = 2.88; 95%CI: 0.99-4.76, p = 0.003) and SRC (mean difference = 268.01 ml/min; β = 2.61; 95%CI: 0.77-4.44, p = 0.006) cohorts demonstrated higher VO2peak and this did not differ based on biological sex. FMI did not differ for MSK (mean difference= -0.10 kg/m2; β= -0.02; 95%CI: -0.22-0.18, p = 0.847) or SRC (mean difference=-0.22 kg/m2; β= -0.05; 95%CI: -0.24-0.15, p = 0.642) cohorts relative to the uninjured cohort for both males and females.

CONCLUSIONS

It is possible to maintain adequate long-term cardiorespiratory fitness and adiposity following adolescent SRC relative to those who only sustained sport related MSK injuries or did not sustain significant injuries as adolescents/adults.

Concussion Incidence by Type of Sport: Differences by Sex, Age Groups, Type of Session, and Level of Play An Overview of Systematic Reviews With Meta-analysis

OBJECTIVES: To (1) summarize pooled prevalence and incidence rates of concussion by type of sport and (2) synthesize the differences in prevalence or incidence rates of concussion by type of sports in terms of sex, age, type of session, and level of competition. DESIGN: An overview of systematic reviews with meta-analysis. LITERATURE SEARCH: CINAHL, Embase, Epistemonikos, PubMed, Scopus, SPORTDiscus, and the Cochrane Library databases were searched. STUDY SELECTION CRITERIA: Systematic reviews with meta-analyses reporting pooled incidence or prevalence of sport-related concussion. DATA SYNTHESIS: AMSTAR 2 was used to assess the methodological quality of reviews. Overlap between reviews was calculated. RESULTS: Ten systematic reviews with meta-analysis were included, all evaluating incidence rates of concussion. There were no meta-analyses of concussion prevalence. Concussions seem to have a higher incidence in rugby, snowboarding, ice hockey, and American football. In reviews that explored sex-based differences across subgroups, there was a higher incidence rate of concussion in baseball-softball, basketball, and soccer in females compared to males. There were no age subgroups analyzed. The incidence of concussions was higher during games compared to practice in American football, ice hockey, rugby, and soccer. Amateur rugby had higher concussion rates compared to professional rugby. CONCLUSIONS: Rugby, snowboarding, ice hockey, and American football had the highest incidence rate of concussion when no other differences (eg, type of session) were considered. However, important methodological flaws were detected, such as the lack of use of the Grading of Recommendations, Assessment, Development, and Evaluations (GRADE) system and subgroups for specific factors (eg, age groups). J Orthop Sports Phys Ther 2024;54(11):1-9. Epub 15 October 2024. doi:10.2519/jospt.2024.12677.

Concussions in Soccer

The identification, management, and prevention of concussion across all competitive sports and athletic populations has been a notable topic of research over the last decade. Soccer is no exception, with over a billion participants worldwide. In soccer, 3 distinct subsets of head injuries are often the contributors to concussion: head-to-equipment, head-to-surface, and head-to-player collisions. Recognition of concussion is crucial, and ideally made on the sideline during competitive play. Recently updated screening tools include the SCAT6 and ChildSCAT6, which are widely utilized at all levels of play. Management of concussion is divided into on-field and in clinic management. Initial management includes removal from the field of play. There is increased emphasis on earlier incorporation of exercise prescription as a means to improve recovery in the concussed athlete. While few objective diagnostic tests exist to identify concussion, many are in development, most notably advanced imaging and biomarker modalities.

Some problems of research exploring sex differences in sport-related concussions: a narrative review

This narrative review scrutinizes research exploring sex-based differences in experiences of sport-related concussion. The article argues that the limitations of epidemiological studies identifying the greater incidence and severity of concussion among females require that these findings are read with caution. It secondly argues that the dominant explanations for these data are based on and extend historical tendencies to "other" female participation in sport and construct male experiences as the "norm". Finally, the article critiques policy recommendations related to these research findings, arguing that they are likely to embed rather than challenge sex inequality in sport, and that they are both impractical and unethical. While this commentary builds on a broader body of work advocating greater sex/gender equality in sports science research, the prominence of social concerns about concussions in sport makes the broader implications of the focus on sex and sport-related concussion particularly problematic and thus in need of redress.

Differences in the technical performance of heading between men and women football players during FIFA World Cup 2022 and FIFA Women's World Cup 2023 matches

Objectives

To compare the incidence of headers, attempted headers, and other head impacts, and the difference in heading descriptors, including technical performance, between men and women in a purposive sample of FIFA World Cup 2022 (FWC22) and FIFA Women's World Cup (FWWC23) matches.

Methods

Video analysis of all observed headers, attempted headers and other head impacts during eight FWC matches (FWC22 (n=4); FWWC23 (n=4)) where the same national teams competed. Heading descriptors (including ball delivery method, purpose of the header and involvement of other players) and technical performance of each header (including controlled or uncontrolled header, use of upper body, point of head contact) were analysed using negative binomial regression analyses with men as the reference group (reported as incidence rate ratios (IRR)). Timing of eye closure was analysed using a t-test; α-error, p=<0.05.

Results

From 973 head impacts, 845 (87%) were headers (FWC22 mean 5.0 headers/player/match, FWWC23 mean 4.6 headers/player/match), 93 (10%) were attempted headers and 35 (4%) were unintentional head impacts. When compared with men, women were less likely to perform controlled headers (73% vs 83%, IRR 1.20, p=0.01), use their foreheads (IRR 2.36, p=<0.001) and their upper body during the header (80% vs 88%, IRR 1.29, p=0.005). Women also closed their eyes earlier before the header (1.91 vs 1.56 frames, d=0.41, p=0.002).

Conclusion

There were significant differences in heading technique between women and men, which could be important to address in training to improve heading performance and potentially reduce short-term and long-term burden of heading.

Does early exercise intolerance effect time to return to play, symptom burden, neurocognition, Vestibular-Ocular-Motor (VOM) function and academic ability in acutely concussed student-athletes?

INTRODUCTION

Early Exercise Intolerance (EEI) is associated with delayed recovery and longer time to Return To Play (RTP), but this has not been established.Participants; (n = 52, male n = 30) UK university-aged rugby-union student-athletes.

METHODS

Student-athletes completed baseline screening (July-October 2021 and 2022). The test battery was repeated within 48 h, 4, 8 and 14 days after a Sports-Related Concussion (SRC) with the Buffalo Concussion Bike or Treadmill Test to set sub-symptom heart rate threshold. Student-athletes then completed a controlled early exercise protocol in-between reassessment (days 3, 5-7 and 9-13). Those with EEI were compared to those with early-exercise tolerance.

OUTCOME MEASURES

Post-Concussion Symptom Scale, Immediate Post-Concussion and Cognitive Test, Vestibular-Ocular Motor Screening Tool and the Revised Perceived Academic Impact Tool.

RESULTS

EEI was seen throughout the initial 14-days post-SRC (23.8%, 22.4%, 25.5%. 25.0%). EEI was associated with a slower reaction time within 48 h (-0.01 (-0.030-0.043) Vs 0.06 (0.033-0.24), p = 0.004) and greater VOMS scores within 48 h; (0.00 (0.00-4.00) Vs 5.50 (2.75-9.00), p = 0.016) and 4 days (0.00 (0.00-2.00) Vs 5.00 (0.00-6.00), p = 0.044). RTP was 12.5 days longer in those with EEI at 14-days post-SRC.

CONCLUSION

EEI is prevalent following an SRC in university-aged student-athletes and was associated with delayed recovery and RTP.

Heading in football: a systematic review of descriptors, definitions, and reporting methods used in heading incidence studies

The primary objective of this systematic review was to describe the number and type of heading descriptors used in all published studies which report on heading incidence in football. The secondary objective was to detail the data collection and reporting methods used in the included studies to present heading incidence data. Eligible studies were identified through searches of five electronic databases: Ovid MEDLINE, CINAHL, EMBASE, SPORTDiscus, and Web of Science, using a combination of free-text keywords (inception to 12th September 2023). Manual searching of reference lists and retrieved systematic reviews was also performed. A descriptive overview and synthesis of the results is presented. From 1620 potentially eligible studies, 71 studies were included, with the following key findings: 1) only 61% of studies defined a header with even fewer (23%) providing an operational definition of a header within the methods; 2) important study and player demographic data including year and country were often not reported; 3) reported heading descriptors and their coding options varied greatly; 4) visual identification of headers was essential when inertial measurement units were used to collect heading incidence data; and 5) there was a lack of standardisation in the reporting methods used in heading incidence studies making comparison between studies challenging. To address these findings, the development of a standardised, internationally supported, operational definition of a header and related heading descriptors should be prioritised. Further recommendations include the development of minimum reporting criteria for heading incidence research.

Use of the concussion check protocol for concussion assessment in a female soccer team over two consecutive seasons in New Zealand

AIM

Address deficiencies in access to sports sideline medical care by using a Concussion Check Protocol (CCP) for non-medically-trained people.

METHOD

A prospective observational cohort study was undertaken on a single amateur female club-based soccer team over two consecutive years in New Zealand utilising a non-medically trained support person termed a Safety officer. CCP is an extension of the King-Devick test with features such as warning signs and symptoms of concussion built into the application. All players suspected of having a potential concussive injury were tested on the match sideline.

RESULTS

The study overall incidence of match-related concussions was 20.8 (95% CI: 11.8 to 36.6) per 1000 match-hrs, with mean missed-match duration of 31 (95% CI: 27.9 to 34.1) days. Twelve players over the study had a significantly slower post-injury KD (49.9 [44.3 to 64.1]s; χ2(1) = 11.0; p = 0.0009; z = -2.9; p = 0.0033; d = 0.30) and/or reported symptoms, compared with their own baseline (47.2 [44.3 to 64.1]s). CCP had an overall sensitivity of 100% (95% CI: 73.5% to 100.0%), specificity of 100% (95% CI: 69.2% to 100.0%) and positive predictive value (PPV) of 100% (84.6% to 100.0%).

CONCLUSION

Sideline use of CCP was undertaken successfully by non-medically trained people and provided a reliable platform for concussion identification.

The spectrum of acute and chronic consequences of neurotrauma in professional and amateur boxing - A call to action is advocated to better understand and prevent this phenomenon

Introduction

Despite changes in regulations, boxing-related injuries and fatalities are still occurring. The numbers available in the literature regarding mortality and long-term consequences may not accurately represent the actual situation. Indeed, the real extent of this phenomenon remains poorly known.

Research question

Delineating the spectrum of acute and chronic consequences of boxing-related traumatic brain injuries (TBI).

Material and methods

Narrative review of the literature concerning acute and chronic boxing-related TBI. Keywords such as mortality, boxing, subdural hematoma were used to search in PubMed and Google scholar. An updated analysis of the Velazquez fatalities collection in boxing was undertaken.

Results

The Velazquez collection includes 2076 fatalities from 1720 to the present with a death rate of 10 athletes per year. More than half of the deaths (N = 1354, 65.2%) occurred after a knock-out, and nearly 75% happened during professional bouts. In Australia, from 1832 to 2020, 163 fatalities were recorded (75% professional). In Japan, from 1952 to 2016, 38 deaths were recorded with a mean age of 23.9 years. Up to 40% of retired professional boxers in the United States were diagnosed with symptoms of chronic brain injury. Clinical dementia is far more prevalent among professional boxers than in amateurs with an incidence of 20%.

Discussion and conclusions

A concerted effort to raise awareness and shed light on boxing-related neuro-trauma is required. Similar considerations can be made for other combat sports or contact sports. A call to action to address this knowledge gap, decrease and prevent this phenomenon is advocated.

The Women's Soccer Health Study: From Head to Toe

OBJECTIVES

Women are under-represented in the sports literature despite increasing rates of sports participation. Our objective was to investigate the risks and benefits of an elite women's soccer career in five health domains: general, musculoskeletal, reproductive endocrinology, post-concussion, and mental.

METHODS

An online survey was distributed to retired US college, semi-professional, professional, and national team soccer players using personal networks, email, and social media. Short validated questionnaires were used to evaluate the health domains, including the Patient-Reported Outcomes Measurement Information System (PROMIS), Single Assessment Numerical Evaluation (SANE), Post-Concussion Symptom Scale (PCSS), and Patient Health Questionnaire (PHQ).

RESULTS

A total of 560 eligible players responded to the survey over a 1-year period. The highest competitive levels were 73% college, 16% semi-professional, 8% professional, and 4% national team. The mean number of years since retirement was 12 (SD = 9), and 17.0% retired for involuntary reasons. The mean SANE scores (0-100 scale as percentage of normal) were knee = 75% (SD = 23), hip = 83% (SD = 23), and shoulder = 87% (SD = 21). The majority (63%) reported that their current activity level included participation in impact sports. A substantial proportion of players reported menstrual irregularities during their careers: 40% had fewer periods with increasing exercise and 22% had no periods for ≥ 3 months. The players (n = 44) who felt that post-concussion symptoms were due to soccer reported more time-loss concussions (F[2] = 6.80, p = 0.002) and symptom severity (F[2] = 30.26, p < 0.0001). Players who recently retired (0-5 years) reported the highest anxiety/depression scores and lowest satisfaction rates compared with those who retired 19+ years ago.

CONCLUSION

Health concerns include musculoskeletal injuries, post-concussion symptoms, and lower mental health in the early years following retirement. This comprehensive survey provides initial results that will lay the foundation for further analyses and prioritize research studies that can help all female athletes.

Biomechanical characteristics of concussive and sub-concussive impacts in youth sports athletes: A systematic review and meta-analysis

This study aimed to quantitatively investigate and report the biomechanical characteristics of concussive and sub-concussive impacts in youth sports. A systematic search was conducted in September 2022 to identify biomechanical impact studies in athletes ≤18 years of age. Twenty-six studies met the inclusion criteria for quantitative synthesis and analysis. DerSimonian Laird random effects model was used to pool data across the included studies. The pooled estimate of mean peak linear and rotational acceleration of concussive impacts in male youth athletes was 85.56 g (95% CI 69.34-101.79) and 4505.58 rad/s² (95% CI 2870.28-6140.98), respectively. The pooled estimate of mean peak linear and rotational acceleration of sub-concussive impacts in youth athletes was 22.89 g (95% CI 20.69-25.08) and 1290.13 rad/s² (95% CI 1050.71-1529.55), respectively. A male vs female analysis in sub-concussive impacts revealed higher linear and rotational acceleration in males and females, respectively. This is the first study to report on impact data in both sexes of youth athletes. Disparity in kinematic impact values suggests future research should aim for standardised measures to reduce heterogeneity in data. Despite this, the data reveals notable impact data that youth athletes are exposed to, suggesting modifications may be required to reduce long-term neurological risks.

Efficacy of aerobic exercise following concussion: a narrative review

Concussion is a type of mild traumatic brain injury which results in symptoms within the physical, cognitive, emotional, and sleep domains. Historically, guidelines established by expert opinion have recommended rest during the initial stages of recovery following a concussion until symptom resolution. However, recent recommendations have shifted to advise an initial period of 24-48 h of rest immediately following concussion with the gradual introduction of light-to-moderate intensity aerobic exercise thereafter. Given the relatively recent transition in recommendations, the aim of this review is to provide an overview of the current literature on the efficacy of aerobic exercise following concussion. The current literature is limited to studies assessing the impact of standardized aerobic exercise following concussion. Upon review, literature suggests participating in aerobic exercise below the point of symptom exacerbation is safe in both the acute and chronic post-concussion symptom stages of recovery and does not delay time to medical clearance. Future large-scale randomized controlled trials assessing the impact of aerobic exercise and differences between males and females would help support the current evidence suggesting aerobic exercise could improve time to recovery following concussion and identify any sex differences in response. As well, future studies with the purpose of identifying optimal aerobic exercise volume and intensity in the treatment of concussion could improve the specificity of the current guidelines.