Mechanisms of Injury Leading to Concussions in Collegiate Soccer Players: A CARE Consortium Study.

BACKGROUND: Few previous studies have investigated how different injury mechanisms leading to sport-related concussion (SRC) in soccer may affect outcomes. PURPOSE: To describe injury mechanisms and evaluate injury mechanisms as predictors of symptom severity, return to play (RTP) initiation, and unrestricted RTP (URTP) in a cohort of collegiate soccer players. STUDY DESIGN: Cohort study; Level of evidence, 2. METHODS: The Concussion Assessment, Research and Education (CARE) Consortium database was used. The mechanism of injury was categorized into head-to-ball, head-to-head, head-to-body, and head-to-ground/equipment. Baseline/acute injury characteristics-including Sports Concussion Assessment Tool-3 total symptom severity (TSS), loss of consciousness (LOC), and altered mental status (AMS); descriptive data; and recovery (RTP and URTP)-were compared. Multivariable regression and Weibull models were used to assess the predictive value of the mechanism of injury on TSS and RTP/URTP, respectively. RESULTS: Among 391 soccer SRCs, 32.7% were attributed to a head-to-ball mechanism, 27.9% to a head-to-body mechanism, 21.7% to a head-to-head mechanism, and 17.6% to a head-to-ground/equipment mechanism. Event type was significantly associated with injury mechanism [χ2(3) = 63; P < .001), such that more head-to-ball concussions occurred in practice sessions (n = 92 [51.1%] vs n = 36 [17.1%]) and more head-to-head (n = 65 [30.8%] vs n = 20 [11.1]) and head-to-body (n = 76 [36%] vs n = 33 [18.3%]) concussions occurred in competition. The primary position was significantly associated with injury mechanism [χ2(3) = 24; P < .004], with goalkeepers having no SRCs from the head-to-head mechanism (n = 0 [0%]) and forward players having the least head-to-body mechanism (n = 15 [19.2%]). LOC was also associated with injury mechanism (P = .034), with LOC being most prevalent in head-to-ground/equipment. Finally, AMS was most prevalent in head-to-ball (n = 54 [34.2%]) and head-to-body (n = 48 [30.4%]) mechanisms [χ2(3) = 9; P = .029]. In our multivariable models, the mechanism was not a predictor of TSS or RTP; however, it was associated with URTP (P = .044), with head-to-equipment/ground injuries resulting in the shortest mean number of days (14 ± 9.1 days) to URTP and the head-to-ball mechanism the longest (18.6 ± 21.6 days). CONCLUSION: The mechanism of injury differed by event type and primary position, and LOC and AMS were different across mechanisms. Even though the mechanism of injury was not a significant predictor of acute symptom burden or time until RTP initiation, those with head-to-equipment/ground injuries spent the shortest time until URTP, and those with head-to-ball injuries had the longest time until URTP.

Low antibody levels associated with significantly increased rate of SARS-CoV-2 infection in a highly vaccinated population from the US National Basketball Association.

SARS-CoV-2 antibody levels may serve as a correlate for immunity and could inform optimal booster timing. The relationship between antibody levels and protection from infection was evaluated in vaccinated individuals from the US National Basketball Association who had antibody levels measured at a single time point from September 12, 2021, to December 31, 2021. Cox proportional hazards models were used to estimate the risk of infection within 90 days of serologic testing by antibody level (<250, 250-800, and >800 AU/mL1 ), adjusting for age, time since last vaccine dose, and history of SARS-CoV-2 infection. Individuals were censored on date of booster receipt. The analytic cohort comprised 2323 individuals and was 78.2% male, 68.1% aged ≤40 years, and 56.4% vaccinated (primary series) with the Pfizer-BioNTech mRNA vaccine. Among the 2248 (96.8%) individuals not yet boosted at antibody testing, 77% completed their primary vaccine series 4-6 months before testing and the median (interquartile range) antibody level was 293.5 (interquartile range: 121.0-740.5) AU/mL. Those with levels <250 AU/mL (adj hazard ratio [HR]: 2.4; 95% confidence interval [CI]: 1.5-3.7) and 250-800 AU/mL (adj HR: 1.5; 95% CI: 0.98-2.4) had greater infection risk compared to those with levels >800 AU/mL. Antibody levels could inform individual COVID-19 risk and booster scheduling.

The "Bubble": What Can Be Learned from the National Basketball Association (NBA)'s 2019-20 Season Restart in Orlando during the COVID-19 Pandemic.

BACKGROUND: The National Basketball Association (NBA) suspended operations in response to the COVID-19 pandemic in March 2020. To safely complete the 2019-20 season, the NBA created a closed campus in Orlando, Florida, known as the NBA "Bubble." More than 5000 individuals lived, worked, and played basketball at a time of high local prevalence of SARS-CoV-2. METHODS: Stringent protocols governed campus life to protect NBA and support personnel from contracting COVID-19. Participants quarantined before departure and upon arrival. Medical and social protocols required that participants remain on campus, test regularly, physically distance, mask, use hand hygiene, and more. Cleaning, disinfection, and air filtration was enhanced. Campus residents were screened daily and confirmed cases of COVID-19 were investigated. RESULTS: In the Bubble population, 148 043 COVID-19 reverse transcriptase PCR (RT-PCR) tests were performed across approximately 5000 individuals; Orlando had a 4% to 15% test positivity rate in this timeframe. There were 44 COVID-19 cases diagnosed either among persons during arrival quarantine or in non-team personnel while working on campus after testing but before receipt of a positive result. No cases of COVID-19 were identified among NBA players or NBA team staff living in the Bubble once cleared from quarantine. CONCLUSIONS: Drivers of success included the requirement for players and team staff to reside and remain on campus, well-trained compliance monitors, unified communication, layers of protection between teams and the outside, activation of high-quality laboratory diagnostics, and available mental health services. An emphasis on data management, evidence-based decision-making, and the willingness to evolve protocols were instrumental to successful operations. These lessons hold broad applicability for future pandemic preparedness efforts.

Optimizing Concussion Care Seeking: A Longitudinal Analysis of Recovery.

BACKGROUND: Approximately half of concussions go undisclosed and therefore undiagnosed. Among diagnosed concussions, 51% to 64% receive delayed medical care. Understanding the influence of undiagnosed concussions and delayed medical care would inform medical and education practices. PURPOSE: To compare postconcussion longitudinal clinical outcomes among (1) individuals with no concussion history, all previous concussions diagnosed, and ≥1 previous concussion undiagnosed, as well as (2) those who have delayed versus immediate symptom onset, symptom reporting, and removal from activity after concussion. STUDY DESIGN: Cohort study; Level of evidence, 2. METHODS: Participants included 2758 military academy cadets and intercollegiate athletes diagnosed with concussion in the CARE Consortium. We determined (1) each participant's previous concussion diagnosis status self-reported at baseline (no history, all diagnosed, ≥1 undiagnosed) and (2) whether the participant had delayed or immediate symptom onset, symptom reporting, and removal from activity. We compared symptom severities, cognition, balance, and recovery duration at baseline, 24 to 48 hours, date of asymptomatic status, and date of unrestricted return to activity using tests of parallel profiles. RESULTS: The ≥1 undiagnosed concussion group had higher baseline symptom burdens (P < .001) than the other 2 groups and poorer baseline verbal memory performance (P = .001) than the all diagnosed group; however, they became asymptomatic and returned to activity sooner than those with no history. Cadets/athletes who delayed symptom reporting had higher symptom burdens 24 to 48 hours after injury (mean ± SE; delayed, 28.8 ± 0.8; immediate, 20.6 ± 0.7), took a median difference of 2 days longer to become asymptomatic, and took 3 days longer to return to activity than those who had immediate symptom reporting. For every 30 minutes of continued participation after injury, days to asymptomatic status increased 8.1% (95% CI, 0.3%-16.4%). CONCLUSION: Clinicians should expect that cadets/athletes who delay reporting concussion symptoms will have acutely higher symptom burdens and take 2 days longer to become asymptomatic. Educational messaging should emphasize the clinical benefits of seeking immediate care for concussion-like symptoms.

Quantifying the impact of immune history and variant on SARS-CoV-2 viral kinetics and infection rebound: A retrospective cohort study.

Background: The combined impact of immunity and SARS-CoV-2 variants on viral kinetics during infections has been unclear. Methods: We characterized 1,280 infections from the National Basketball Association occupational health cohort identified between June 2020 and January 2022 using serial RT-qPCR testing. Logistic regression and semi-mechanistic viral RNA kinetics models were used to quantify the effect of age, variant, symptom status, infection history, vaccination status and antibody titer to the founder SARS-CoV-2 strain on the duration of potential infectiousness and overall viral kinetics. The frequency of viral rebounds was quantified under multiple cycle threshold (Ct) value-based definitions. Results: Among individuals detected partway through their infection, 51.0% (95% credible interval [CrI]: 48.3-53.6%) remained potentially infectious (Ct <30) 5 days post detection, with small differences across variants and vaccination status. Only seven viral rebounds (0.7%; N=999) were observed, with rebound defined as 3+days with Ct <30 following an initial clearance of 3+days with Ct ≥30. High antibody titers against the founder SARS-CoV-2 strain predicted lower peak viral loads and shorter durations of infection. Among Omicron BA.1 infections, boosted individuals had lower pre-booster antibody titers and longer clearance times than non-boosted individuals. Conclusions: SARS-CoV-2 viral kinetics are partly determined by immunity and variant but dominated by individual-level variation. Since booster vaccination protects against infection, longer clearance times for BA.1-infected, boosted individuals may reflect a less effective immune response, more common in older individuals, that increases infection risk and reduces viral RNA clearance rate. The shifting landscape of viral kinetics underscores the need for continued monitoring to optimize isolation policies and to contextualize the health impacts of therapeutics and vaccines. Funding: Supported in part by CDC contract #200-2016-91779, a sponsored research agreement to Yale University from the National Basketball Association contract #21-003529, and the National Basketball Players Association.

Current Sport Organization Guidelines From the AMSSM 2019 Youth Early Sport Specialization Research Summit.

CONTEXT: Youth athletes may be at elevated risk for adverse health due to sport specialization. Sport organizations have developed guidelines for participation during growth and development. OBJECTIVE: To assess youth sport development guidelines using a 15-item framework across sport organizations and governing bodies in soccer, basketball, ice hockey, and swimming. DATA SOURCES: English-language results from January 1, 2000, to December 31, 2018, from published sport organization guidelines and athlete development plans. STUDY SELECTION: Two investigators independently reviewed publications identified from sport organizations. A total of 23 guidelines were incorporated, including 5 general sport organizations and 18 sport-specific guidelines. STUDY DESIGN: Systematic review. LEVEL OF EVIDENCE: Level 4. DATA EXTRACTION: Two investigators independently identified all recommendations that fit within a predetermined rubric of recommendations encompassing 4 domains: Psychological Development/Approach, Physical Development/Load, Facilities and Resources, and Timing and Monitoring of Specialization. Sport-specific guidelines on volume were summarized. RESULTS: Sport organizations and sport-specific guidelines had consensus on 2 items out of the 15-item: emphasis on early skill development and access to well-trained coaches. While recommended by all sports organization, multisport participation was emphasized by 3 of 4 sports, excluding soccer. Volume recommendations were inconsistent between and within sports. No group proposed methods to monitor athlete well-being. CONCLUSION: This review highlights areas of agreement within sport organizations and governing bodies. Creating a framework to guide youth sport specialization may lead to specific and consistent guidelines.

Systematic Review of Health Organization Guidelines Following the AMSSM 2019 Youth Early Sport Specialization Summit.

CONTEXT: Youth sport specialization may place young athletes at increased risk for negative impacts to their physical and/or psychological health. In response to these health concerns, several health organizations have created guidelines and position statements to guide parents and practitioners toward best practices for management of the young athlete. OBJECTIVE: To systematically review and synthesize current organizations' recommendations and guidelines regarding youth sport specialization. DATA SOURCES: English-language articles from January 1, 2000, to December 31, 2018, in the NCBI Pubmed, Embase, Cochrane, CINAHL, and SPORTDiscus databases. STUDY SELECTION: Articles that reported on recommendations or interventions by health organizations or health representatives of sports organizations. A total of 56 articles were assessed, with 11 meeting inclusion eligibility criteria. STUDY DESIGN: Systematic review. LEVEL OF EVIDENCE: Level 4. DATA EXTRACTION: Two investigators independently identified all recommendations within the results that fit within a 15-item framework encompassing 4 domains: Psychological Development/Approach, Physical Development/Load, Facilities and Resources, and Timing and Monitoring of Specialization. RESULTS: Recommendations across organizations were primarily clustered in the Physical Development/Load (43%), Facilities and Resources (48%), and Sport Specialization (55%) domains. In contrast, the Psychological Development/Approach domain had fewer recommendations (20%). The most common recommendations endorsed concepts: "Monitor athlete well-being," "Youth athletes need access to well-trained, quality coaches," "Multi-sport participation," "Limit early organized participation and/or training," and "Parents require awareness of training, coaching, and best practices." The level of evidence provided to support a given recommendation varied significantly. The level of detail and the consistency of terms used throughout the results were typically low. Recommendations were frequently made without reference to potential outcome measures or specific strategies that could be used for practical implementation in the community. CONCLUSION: There was broad representation of different aspects of specialization but limited consistency between health organization guidelines. Adopting a framework for recommendations as used in this review could assist organizations in structuring future recommendations that are specific, measurable, and framed in a manner that will promote action in the youth sport community.

Severe Acute Respiratory Syndrome Coronavirus 2 Reinfection: A Case Series From a 12-Month Longitudinal Occupational Cohort.

Findings are described in 7 patients with severe acute respiratory syndrome coronavirus 2 reinfection from the National Basketball Association 2020-2021 occupational testing cohort, including clinical details, antibody test results, genomic sequencing, and longitudinal reverse-transcription polymerase chain reaction results. Reinfections were infrequent and varied in clinical presentation, viral dynamics, and immune response.

Age of Early Specialization, Competitive Volume, Injury, and Sleep Habits in Youth Sport: A Preliminary Study of US Youth Basketball.

BACKGROUND: Concerns for youth sports in the United States often focus on early sport specialization, overemphasis on competition, injuries, and burnout. Little research has addressed relationships among the preceding and other concerns, including time away from organized sport, sleep, and perceptions of physical and psychological well-being. HYPOTHESIS: There is an association between reported competitive gameplay volume and specialization, injury, and fatigue among elite youth basketball players. STUDY DESIGN: Cross-sectional study; convenience sample. LEVEL OF EVIDENCE: Level 4. METHODS: An anonymous questionnaire was administered to a convenience sample of youth basketball players between 13 and 18 years of age from across the United States. Participants were queried about multiple factors, including the extent of their participation in organized basketball and other sports, time away from organized basketball, injury, sleep, and feelings of exhaustion related to basketball participation. RESULTS: A total of 772 participants (145 girls, 627 boys) completed a survey. All participants played for a select or elite club basketball team and/or a high school basketball team. Overall, 49% played more than 50 games within the past year. A total of 73% were specialized in basketball, 58% prior to age 14 years, and 35% prior to age 11 years. In all, 70% reported less than 1 month away from organized basketball within the past year, and 28% reported no time away. A total of 54% reported sleeping less than the recommended 8 hours each night during the school year. Within the prior year, 55% reported feeling physically exhausted and 45% reported feeling mentally exhausted from basketball. Regression analysis did not find any significant relationships between early specialization prior to age 14 years and basketball-related injury or feelings of mental or physical exhaustion. CONCLUSION: In this select group of youth basketball players, the majority specialized in basketball prior to age 14 years and reported a large number of competitive events with little time away from organized basketball. CLINICAL RELEVANCE: The results from a sample of highly competitive youth basketball players indicate issues that warrant further attention and research regarding the potential impact of specialization, frequent competitions, lack of time away from organized sport, and perceptions of well-being in young athletes.

Viral dynamics of acute SARS-CoV-2 infection and applications to diagnostic and public health strategies.

SARS-CoV-2 infections are characterized by viral proliferation and clearance phases and can be followed by low-level persistent viral RNA shedding. The dynamics of viral RNA concentration, particularly in the early stages of infection, can inform clinical measures and interventions such as test-based screening. We used prospective longitudinal quantitative reverse transcription PCR testing to measure the viral RNA trajectories for 68 individuals during the resumption of the 2019-2020 National Basketball Association season. For 46 individuals with acute infections, we inferred the peak viral concentration and the duration of the viral proliferation and clearance phases. According to our mathematical model, we found that viral RNA concentrations peaked an average of 3.3 days (95% credible interval [CI] 2.5, 4.2) after first possible detectability at a cycle threshold value of 22.3 (95% CI 20.5, 23.9). The viral clearance phase lasted longer for symptomatic individuals (10.9 days [95% CI 7.9, 14.4]) than for asymptomatic individuals (7.8 days [95% CI 6.1, 9.7]). A second test within 2 days after an initial positive PCR test substantially improves certainty about a patient's infection stage. The effective sensitivity of a test intended to identify infectious individuals declines substantially with test turnaround time. These findings indicate that SARS-CoV-2 viral concentrations peak rapidly regardless of symptoms. Sequential tests can help reveal a patient's progress through infection stages. Frequent, rapid-turnaround testing is needed to effectively screen individuals before they become infectious.

The 2020 NBA Orthobiologics Consensus Statement.

This 2020 NBA Orthobiologics Consensus Statement provides a concise summary of available literature and practical clinical guidelines for team physicians and players. We recognize that orthobiologic injections are a generally safe treatment modality with a significant potential to reduce pain and expedite early return to play in specific musculoskeletal injuries. The use of orthobiologics in sports medicine to safely reduce time loss and reinjury is of considerable interest, especially as it relates to the potential effect on a professional athlete. While these novel substances have potential to enhance healing and regeneration of injured tissues, there is a lack of robust data to support their regular use at this time. There are no absolutes when considering the implementation of orthobiologics, and unbiased clinical judgment with an emphasis on player safety should always prevail. Current best evidence supports the following: Key Points There is support for the use of leukocyte-poor platelet-rich plasma in the treatment of knee osteoarthritis. There is support for consideration of using leukocyte-rich platelet-rich plasma for patellar tendinopathy. The efficacy of using mesenchymal stromal cell injections in the management of joint and soft tissue injuries remains unproven at this time. There are very few data to suggest that current cell therapy treatments lead to any true functional tissue regeneration. Meticulous and sterile preparation guidelines must be followed to minimize the risk for infection and adverse events if these treatments are pursued.Given the high variability in orthobiologic formulations, team physicians must stay up-to-date with the most recent peer-reviewed literature and orthobiologic preparation protocols for specific injuries.Evidence-based treatment algorithms are necessary to identify the optimal orthobiologic formulations for specific tissues and injuries in athletes.Changes in the regulatory environment and improved standardization are required given the exponential increase in utilization as novel techniques and substances are introduced into clinical practice.

SARS-CoV-2 Transmission Risk Among National Basketball Association Players, Staff, and Vendors Exposed to Individuals With Positive Test Results After COVID-19 Recovery During the 2020 Regular and Postseason.

Importance: Clinical data are lacking regarding the risk of viral transmission from individuals who have positive reverse-transcription-polymerase chain reaction (RT-PCR) SARS-CoV-2 test results after recovery from COVID-19. Objective: To describe case characteristics, including viral dynamics and transmission of infection, for individuals who have clinically recovered from SARS-CoV-2 infection but continued to have positive test results following discontinuation of isolation precautions. Design, Setting, and Participants: This retrospective cohort study used data collected from June 11, 2020, to October 19, 2020, as part of the National Basketball Association (NBA) closed campus occupational health program in Orlando, Florida, which required daily RT-PCR testing and ad hoc serological testing for SARS-CoV-2 IgG antibodies. Nearly 4000 NBA players, staff, and vendors participated in the NBA's regular and postseason occupational health program in Orlando. Persistent positive cases were those who recovered from a documented SARS-CoV-2 infection, satisfied US Centers for Disease Control and Prevention criteria for discontinuation of isolation precautions, and had at least 1 postinfection positive RT-PCR test(s) result. Exposures: Person-days of participation in indoor, unmasked activities that involved direct exposure between persistent positive cases and noninfected individuals. Main Outcomes and Measures: Transmission of SARS-CoV-2 following interaction with persistent positive individuals, as measured by the number of new COVID-19 cases in the Orlando campus program. Results: Among 3648 individuals who participated, 36 (1%) were persistent positive cases, most of whom were younger than 30 years (24 [67%]) and male (34 [94%]). Antibodies were detected in 33 individuals (91.7%); all remained asymptomatic following the index persistent positive RT-PCR result. Cycle threshold values for persistent positive RT-PCR test results were typically above the Roche cobas SARS-CoV-2 limit of detection. Cases were monitored for up to 100 days (mean [SD], 51 [23.9] days), during which there were at least 1480 person-days of direct exposure activities, with no transmission events or secondary infections of SARS-CoV-2 detected (0 new cases). Conclusions and Relevance: In this retrospective cohort study of the 2020 NBA closed campus occupational health program, recovered individuals who continued to test positive for SARS-CoV-2 following discontinuation of isolation were not infectious to others. These findings support time-based US Centers of Disease Control and Prevention recommendations for ending isolation.

Prevalence of Inflammatory Heart Disease Among Professional Athletes With Prior COVID-19 Infection Who Received Systematic Return-to-Play Cardiac Screening.

Importance: The major North American professional sports leagues were among the first to return to full-scale sport activity during the coronavirus disease 2019 (COVID-19) pandemic. Given the unknown incidence of adverse cardiac sequelae after COVID-19 infection in athletes, these leagues implemented a conservative return-to-play (RTP) cardiac testing program aligned with American College of Cardiology recommendations for all athletes testing positive for COVID-19. Objective: To assess the prevalence of detectable inflammatory heart disease in professional athletes with prior COVID-19 infection, using current RTP screening recommendations. Design, Setting, and Participants: This cross-sectional study reviewed RTP cardiac testing performed between May and October 2020 on professional athletes who had tested positive for COVID-19. The professional sports leagues (Major League Soccer, Major League Baseball, National Hockey League, National Football League, and the men's and women's National Basketball Association) implemented mandatory cardiac screening requirements for all players who had tested positive for COVID-19 prior to resumption of team-organized sports activities. Exposures: Troponin testing, electrocardiography (ECG), and resting echocardiography were performed after a positive COVID-19 test result. Interleague, deidentified cardiac data were pooled for collective analysis. Those with abnormal screening test results were referred for additional testing, including cardiac magnetic resonance imaging and/or stress echocardiography. Main Outcomes and Measures: The prevalence of abnormal RTP test results potentially representing COVID-19-associated cardiac injury, and results and outcomes of additional testing generated by the initial screening process. Results: The study included 789 professional athletes (mean [SD] age, 25 [3] years; 777 men [98.5%]). A total of 460 athletes (58.3%) had prior symptomatic COVID-19 illness, and 329 (41.7%) were asymptomatic or paucisymptomatic (minimally symptomatic). Testing was performed a mean (SD) of 19 (17) days (range, 3-156 days) after a positive test result. Abnormal screening results were identified in 30 athletes (3.8%; troponin, 6 athletes [0.8%]; ECG, 10 athletes [1.3%]; echocardiography, 20 athletes [2.5%]), necessitating additional testing; 5 athletes (0.6%) ultimately had cardiac magnetic resonance imaging findings suggesting inflammatory heart disease (myocarditis, 3; pericarditis, 2) that resulted in restriction from play. No adverse cardiac events occurred in athletes who underwent cardiac screening and resumed professional sport participation. Conclusions and Relevance: This study provides large-scale data assessing the prevalence of relevant COVID-19-associated cardiac pathology with implementation of current RTP screening recommendations. While long-term follow-up is ongoing, few cases of inflammatory heart disease have been detected, and a safe return to professional sports activity has thus far been achieved.

Assessment of Blood Biomarker Profile After Acute Concussion During Combative Training Among US Military Cadets: A Prospective Study From the NCAA and US Department of Defense CARE Consortium.

Importance: Validation of protein biomarkers for concussion diagnosis and management in military combative training is important, as these injuries occur outside of traditional health care settings and are generally difficult to diagnose. Objective: To investigate acute blood protein levels in military cadets after combative training-associated concussions. Design, Setting, and Participants: This multicenter prospective case-control study was part of a larger cohort study conducted by the National Collegiate Athletic Association and the US Department of Defense Concussion Assessment Research and Education (CARE) Consortium from February 20, 2015, to May 31, 2018. The study was performed among cadets from 2 CARE Consortium Advanced Research Core sites: the US Military Academy at West Point and the US Air Force Academy. Cadets who incurred concussions during combative training (concussion group) were compared with cadets who participated in the same combative training exercises but did not incur concussions (contact-control group). Clinical measures and blood sample collection occurred at baseline, the acute postinjury point (<6 hours), the 24- to 48-hour postinjury point, the asymptomatic postinjury point (defined as the point at which the cadet reported being asymptomatic and began the return-to-activity protocol), and 7 days after return to activity. Biomarker levels and estimated mean differences in biomarker levels were natural log (ln) transformed to decrease the skewness of their distributions. Data were collected from August 1, 2016, to May 31, 2018, and analyses were conducted from March 1, 2019, to January 14, 2020. Exposure: Concussion incurred during combative training. Main Outcomes and Measures: Proteins examined included glial fibrillary acidic protein, ubiquitin C-terminal hydrolase-L1, neurofilament light chain, and tau. Quantification was conducted using a multiplex assay (Simoa; Quanterix Corp). Clinical measures included the Sport Concussion Assessment Tool-Third Edition symptom severity evaluation, the Standardized Assessment of Concussion, the Balance Error Scoring System, and the 18-item Brief Symptom Inventory. Results: Among 103 military service academy cadets, 67 cadets incurred concussions during combative training, and 36 matched cadets who engaged in the same training exercises did not incur concussions. The mean (SD) age of cadets in the concussion group was 18.6 (1.3) years, and 40 cadets (59.7%) were male. The mean (SD) age of matched cadets in the contact-control group was 19.5 (1.3) years, and 25 cadets (69.4%) were male. Compared with cadets in the contact-control group, those in the concussion group had significant increases in glial fibrillary acidic protein (mean difference in ln values, 0.34; 95% CI, 0.18-0.50; P < .001) and ubiquitin C-terminal hydrolase-L1 (mean difference in ln values, 0.97; 95% CI, 0.44-1.50; P < .001) levels at the acute postinjury point. The glial fibrillary acidic protein level remained high in the concussion group compared with the contact-control group at the 24- to 48-hour postinjury point (mean difference in ln values, 0.22; 95% CI, 0.06-0.38; P = .007) and the asymptomatic postinjury point (mean difference in ln values, 0.21; 95% CI, 0.05-0.36; P = .01). The area under the curve for all biomarkers combined, which was used to differentiate cadets in the concussion and contact-control groups, was 0.80 (95% CI, 0.68-0.93; P < .001) at the acute postinjury point. Conclusions and Relevance: This study's findings indicate that blood biomarkers have potential for use as research tools to better understand the pathobiological changes associated with concussion and to assist with injury identification and recovery from combative training-associated concussions among military service academy cadets. These results extend the previous findings of studies of collegiate athletes with sport-associated concussions.

Defining a Research Agenda for Youth Sport Specialization in the United States: The AMSSM Youth Early Sport Specialization Summit.

ABSTRACT: Sport specialization is becoming increasingly common among youth and adolescent athletes in the United States and many have raised concern about this trend. Although research on sport specialization has grown significantly, numerous pressing questions remain pertaining to short- and long-term effects of specialization on the health and well-being of youth, including the increased risk of overuse injury and burnout. Many current elite athletes did not specialize at an early age. Methodological and study design limitations impact the quality of current literature, and researchers need to prioritize pressing research questions to promote safe and healthy youth sport participation. The American Medical Society for Sports Medicine hosted a Youth Early Sport Specialization Summit in April 2019 with the goal of synthesizing and reviewing current scientific knowledge and developing a research agenda to guide future research in the field based on the identified gaps in knowledge. This statement provides a broad summary of the existing literature, gaps and limitations in current evidence, and identifies key research priorities to help guide researchers conducting research on youth sport specialization. Our goals are to help improve the quality and relevance of research on youth sport specialization and to ultimately assure that opportunities for healthy and safe sport participation continue for all youth.

Defining a research agenda for youth sport specialisation in the USA: the AMSSM Youth Early Sport Specialization Summit.

Sport specialisation is becoming increasingly common among youth and adolescent athletes in the USA and many have raised concern about this trend. Although research on sport specialisation has grown significantly, numerous pressing questions remain pertaining to short-term and long-term effects of specialisation on the health and well-being of youth, including the increased risk of overuse injury and burnout. Many current elite athletes did not specialise at an early age. Methodological and study design limitations impact the quality of current literature, and researchers need to prioritise pressing research questions to promote safe and healthy youth sport participation. The American Medical Society for Sports Medicine hosted a Youth Early Sport Specialization Summit in April 2019 with the goal of synthesising and reviewing current scientific knowledge and developing a research agenda to guide future research in the field based on the identified gaps in knowledge. This statement provides a broad summary of the existing literature, gaps and limitations in current evidence and identifies key research priorities to help guide researchers conducting research on youth sport specialisation. Our goals are to help improve the quality and relevance of research on youth sport specialisation and to ultimately assure that opportunities for healthy and safe sport participation continue for all youth.

Return to sport for North American professional sport leagues in the context of COVID-19.

COVID-19 is a respiratory illness that can spread from person to person. A range of clinical scenarios exist, from an asymptomatic disease course to SARS and death. This document describes important considerations for 5 North American professional sports leagues (Major League Baseball, Major League Soccer, National Basketball Association, National Football League and National Hockey league) assessing when and how to resume phased operations, including practices and games. Sports should prioritise and promote the health and safety of athletes, team and operational staff, and other participants, and should not unduly increase those individuals' relative health risk while contributing to economic recovery, providing entertainment for the public and leading a responsible restoration of civic life. Because elite professional sport ordinarily is conducted in a controlled environment, professional sports leagues may be able to achieve these goals. This document is focused on professional sports leagues in North America, and although many of the statements are generalisable to professional sporting settings throughout the world, other considerations may apply to sports in other countries.

Sports Performance and Injury Research: Methodologic Limitations and Recommendations for Future Improvements.

Evidence-based research has resulted in incredible advances in sports medicine and is an important component of minimizing injury risk. Such research is similarly important when applied to care delivery to athletes after injury. For research into injury reduction and treatment outcomes to be most impactful, however, the methods must be of sufficient rigor to generate high-quality evidence. Two recent trends in sports injury research have led to specific concerns about evidence quality: 1) use of athletic performance metrics as an injury or treatment outcome and 2) use of publicly available data for injury or treatment research.