Neural Mechanisms Associated With Postural Control in Collegiate Soccer and Non-Soccer Athletes.

BACKGROUND AND PURPOSE: Sport-specific training may improve postural control, while repetitive head acceleration events (RHAEs) may compromise it. Understanding the neural mechanisms underlying postural control may contextualize changes due to training and RHAE. The goal of this study was to determine whether postural sway during the Balance Error Scoring System (BESS) is related to white matter organization (WMO) in collegiate athletes. METHODS: Collegiate soccer (N = 33) and non-soccer athletes (N = 44) completed BESS and diffusion tensor imaging. Postural sway during each BESS stance, fractional anisotropy (FA), and mean diffusivity (MD) were extracted for each participant. Partial least squares analyses determined group differences in postural sway and WMO and the relationship between postural sway and WMO in soccer and non-soccer athletes separately. RESULTS: Soccer athletes displayed better performance during BESS 6, with lower FA and higher MD in the medial lemniscus (ML) and inferior cerebellar peduncle (ICP), compared to non-soccer athletes. In soccer athletes, lower sway during BESS 2, 5, and 6 was associated with higher FA and lower MD in the corticospinal tract, ML, and ICP. In non-soccer athletes, lower sway during BESS 2 and 4 was associated with higher FA and lower MD in the ML and ICP. BESS 1 was associated with higher FA, and BESS 3 was associated with lower MD in the same tracts in non-soccer athletes. DISCUSSION AND CONCLUSIONS: Soccer and non-soccer athletes showed unique relationships between sway and WMO, suggesting that sport-specific exposures are partly responsible for changes in neurological structure and accompanying postural control performance and should be considered when evaluating postural control after injury.Video Abstract available for more insights from the authors (see the Video, Supplemental Digital Content, available at: http://links.lww.com/JNPT/A472).

The Interval Between Concussions Does Not Influence Time to Asymptomatic or Return to Play: A CARE Consortium Study.

INTRODUCTION: The purpose of this study was to determine if the time interval between two concussive events influences the number of days to asymptomatic status, days to return to play, or performance on common post-concussion assessments following the second concussion. METHODS: Data from 448 collegiate athletes and service academy cadets with two concussions (time between concussions: median 295.0 days [interquartile range: 125.0-438.2]), 40.0% female) were analyzed from Concussion Assessment Research and Education (CARE) Consortium institutions between 2014 and 2020. Days between concussions was the primary predictor variable. Primary outcome measures included time to asymptomatic and time to return to play following the second concussion. Secondary outcome measures included total number of symptoms, total symptom severity, Balance Error Scoring System total score, and Standardized Assessment of Concussion total score within 48 h of their second concussion. RESULTS: Time between concussions did not significantly contribute to the multivariate time to asymptomatic (p = 0.390), time to return to play (p = 0.859), or the secondary outcomes (p-range = 0.165-0.477) models. Time to asymptomatic (p = 0.619) or return to play (p = 0.524) did not differ between same-season and different-season concussions. Sex significantly contributed to the return to play (p = 0.005) multivariate model. Delayed symptom onset and immediate removal from play/competition significantly contributed to the total number of symptoms (p = 0.001, p = 0.014) and symptom severity (p = 0.011, p = 0.022) multivariate models. CONCLUSION: These results suggest that in a population with a large period between injuries, the time between concussions may not be relevant to clinical recovery.

Wearable Loop Sensor for Bilateral Knee Flexion Monitoring.

We have previously reported wearable loop sensors that can accurately monitor knee flexion with unique merits over the state of the art. However, validation to date has been limited to single-leg configurations, discrete flexion angles, and in vitro (phantom-based) experiments. In this work, we take a major step forward to explore the bilateral monitoring of knee flexion angles, in a continuous manner, in vivo. The manuscript provides the theoretical framework of bilateral sensor operation and reports a detailed error analysis that has not been previously reported for wearable loop sensors. This includes the flatness of calibration curves that limits resolution at small angles (such as during walking) as well as the presence of motional electromotive force (EMF) noise at high angular velocities (such as during running). A novel fabrication method for flexible and mechanically robust loops is also introduced. Electromagnetic simulations and phantom-based experimental studies optimize the setup and evaluate feasibility. Proof-of-concept in vivo validation is then conducted for a human subject performing three activities (walking, brisk walking, and running), each lasting 30 s and repeated three times. The results demonstrate a promising root mean square error (RMSE) of less than 3° in most cases.

Postinjury Outcomes After Non-Sport-Related Concussion: A CARE Consortium Study.

CONTEXT: Concussion research has primarily focused on sport-related mechanisms and excluded non-sport-related mechanisms. In adult populations, non-sport-related concussions (non-SRCs) demonstrated worse clinical outcomes compared with sport-related concussions (SRCs); however, investigations of non-SRCs in college-aged patients are limited. OBJECTIVES: To examine clinical outcomes in collegiate athletes with non-SRCs compared with SRCs and explore sex differences in outcomes among collegiate athletes with non-SRCs. DESIGN: Prospective cohort study. SETTING: Clinical setting. PATIENTS OR OTHER PARTICIPANTS: A total of 3500 athletes were included (n = 555 with non-SRCs, 42.5% female) from colleges or universities and service academies participating in the National Collegiate Athletic Association Department of Defense Concussion Assessment, Research and Education (CARE) Consortium. MAIN OUTCOME MEASURE(S): Dichotomous outcomes (yes or no) consisted of immediate reporting, mental status alterations, loss of consciousness, posttraumatic amnesia, retrograde amnesia, motor impairments, delayed symptom presentation, and required hospital transport. Continuous outcomes were symptom severity, days with concussion symptoms, and days lost to injury. Data were collected within 24 to 48 hours of injury and at return to play. Adjusted relative risks (ARRs) compared the likelihood of dichotomous outcomes by mechanism and by sex within patients with non-SRCs. Multivariate negative binomial regressions were used to assess group differences in continuous variables. RESULTS: Athletes with non-SRCs were less likely to report immediately (ARR = 0.73, 95% CI = 0.65, 0.81) and more likely to report delayed symptom presentation (ARR = 1.17, 95% CI = 1.03, 1.32), loss of consciousness (ARR = 3.15, 95% CI = 2.32, 4.28), retrograde amnesia (ARR = 1.77, 95% CI = 1.22, 2.57), and motor impairment (ARR = 1.45, 95% CI = 1.14, 1.84). Athletes with non-SRCs described greater symptom severity, more symptomatic days, and more days lost to injury (P < .001) compared with those who had SRCs. Within the non-SRC group, female athletes indicated greater symptom severity, more symptomatic days, and more days lost to injury (P < .03) than male athletes. CONCLUSIONS: Athletes with non-SRCs had worse postinjury outcomes compared with those who had SRCs, and female athletes with non-SRCs had worse recovery metrics than male athletes. Our findings suggest that further investigation of individuals with non-SRCs is needed to improve concussion reporting and management.

Sex Differences in Recovery Trajectories of Assessments for Sport-Related Concussion Among NCAA Athletes: A CARE Consortium Study.

OBJECTIVES: The purpose of this study was to determine sex differences in recovery trajectories of assessments for sport-related concussion using Concussion Assessment, Research and Education (CARE) Consortium data. METHODS: National Collegiate Athletic Association athletes (N = 906; 61% female) from sex-comparable sports completed a pre-season baseline assessment and post-sport-related concussion assessments within 6 h of injury, 24-48 h, when they initiated their return to play progression, when they were cleared for unrestricted return to play, and 6 months post-injury. Assessments included the Standardized Assessment of Concussion, Balance Error Scoring System, Brief Symptom Inventory-18, Immediate Post-concussion Assessment and Cognitive Testing (ImPACT), Sport Concussion Assessment Tool-3 symptom evaluation, Clinical Reaction Time, King-Devick test, Vestibular Ocular Motor Screen, 12-item Short-Form Health Survey, Hospital Anxiety and Depression Scale, and Satisfaction with Life Scale. RESULTS: Only the Vestibular Ocular Motor Screen Total Symptom Score at the 24-48 h timepoint (p = 0.005) was statistically significantly different between sexes. Specifically, female athletes (mean = 60.2, 95% confidence interval [CI] 51.5-70.4) had higher Vestibular Ocular Motor Screen Total Symptom Scores than male athletes (mean = 36.9, 95% CI 27.6-49.3), but this difference resolved by the time of return-to-play initiation (female athletes, mean = 1.8, 95% CI 1.1-2.9; male athletes, mean = 4.1, 95% CI 1.5-10.9). CONCLUSIONS: Sport-related concussion recovery trajectories for most assessments were similar for female and male National Collegiate Athletic Association athletes except for Vestibular Ocular Motor Screen symptoms within 48 h of sport-related concussion, which was greater in female athletes. Female athletes had a greater symptom burden across all timepoints, suggesting that cross-sectional observations may indicate sex differences despite similar recovery trajectories.

Characterizing Head Acceleration Events in Law Enforcement Cadets During Subject Control Technique Training.

Law enforcement cadets (LECs) complete weeks of subject control technique training. Similar sport-related combat training has been shown to expose participants to head acceleration events (HAEs) that have potential to result in short- and long-term impairments. The purpose of this study was to describe the number and magnitude of HAEs in LECs throughout their training. 37 LECs (7 females; age = 30.6 ± 8.8 years; BMI = 30.0 ± 6.0) were recruited from a law enforcement organization. Participants wore instrumented mouthguards, which recorded all HAEs exceeding a resultant 5 g threshold for training sessions with the potential for HAEs. Participants completed three defensive tactics (DT) training sessions, a DT skill assessment (DTA), and three boxing sessions. Outcome measures included the number of HAEs, peak linear acceleration (PLA), and peak rotational velocity (PRV). There were 2758 true-positive HAEs recorded across the duration of the study. Boxing sessions accounted for 63.7% of all true-positive HAEs, while DT accounted for 31.4% and DTA accounted for 4.9%. Boxing sessions resulted in a higher number of HAEs per session (F2,28 = 48.588, p < 0.001, ηp2 = 0.776), and higher median PLA (F2,28 = 8.609, p = 0.001, ηp2 = 0.381) and median PRV (F2,28 = 11.297, p < 0.001, ηp2 = 0.447) than DT and DTA. The LECs experience a high number of HAEs, particularly during boxing sessions. Although this training is necessary for job duties, HAE monitoring may lead to modifications in training structure to improve participant safety and enhance recovery.

Female Collegiate Athletes' Concussion Characteristics and Recovery Patterns: A Report from the NCAA-DoD CARE Consortium.

Concussion has been described in the United States (US) collegiate student-athlete population, but female-specific findings are often underrepresented and underreported. Our study aimed to describe female collegiate student-athletes' initial injury characteristics and return to activity outcomes following concussion. Female collegiate student-athletes (n = 1393) from 30-US institutions experienced a concussion and completed standardized, multimodal concussion assessments from pre-injury through unrestricted return to play (uRTP) in this prospective, longitudinal cohort study. Initial injury presentation characteristics, assessment, and return to activity outcomes [<48-h (acute), return to learn, initiate return to play (iRTP), uRTP] were collected. We used descriptive statistics to report injury characteristics, return to activity outcomes, and post-injury assessment performance change categorization (worsened, unchanged, improved) based on change score confidence rank criteria across sport contact classifications [contact (n = 661), limited (n = 446), non-contact (n = 286)]. The median (25th to 75th percentile) days to return to learn was 6.0 (3.0-10.0), iRTP was 8.1 (4.8-13.8), and uRTP was 14.8 (9.9-24.0), but varied by contact classification. Across contact levels, the majority experienced worse SCAT total symptom severity (72.8-82.6%), ImPACT reaction time (91.2-92.6%), and BSI-18 total score (45.2-51.8%) acutely relative to baseline, but unchanged BESS total errors (58.0-60.9%), SAC total score (71.5-76.1%), and remaining ImPACT domains (50.6-66.5%). Our findings provide robust estimates of the typical female collegiate student-athlete presentation and recovery trajectory following concussion, with overall similar findings to the limited female collegiate student-athlete literature. Overall varying confidence rank classification was observed acutely. Our findings provide clinically-relevant insights for athletes, clinicians, researchers, and policymakers to inform efforts specific to females experiencing concussion.

Quantitative Analysis of Ball-Head Impact Exposure in Youth Soccer Players.

Since the implementation of the US Soccer heading guidelines released in 2015, little to no research on ball-head impact exposure in the United States youth soccer population has been conducted. The purpose was to compare ball-head impact exposure across sex and age in youth soccer players over a weekend tournament. Ten male and female games for each age group (Under-12 [U12], U13, and U14) were video recorded at a weekend tournament for a total of 60 games. Ball-head impact exposure for each game was then coded following a review of each recording. Male players were 2.8 times more likely to have ball-head impacts than female players, (p < 0.001) particularly in the U14 age group when compared to the U12 age group (p = 0.012). Overall 92.4% of players experienced 0-1 ball-head impacts per game with the remaining players experiencing 2+ ball-head impacts per game. Ball-head impact exposure levels are low in the youth players. Most youth soccer players do not head the soccer ball during match play and those that did, only headed the ball on average once per game. Overall, the difference in ball-head impact exposure per player was less than 1 between all the groups, which may have no clinical meaning.

Preinjury Measures Do Not Predict Future Concussion Among Collegiate Student-Athletes: Findings From the CARE Consortium.

ABSTRACT: This prospective cohort study aimed to determine whether preinjury characteristics and performance on baseline concussion assessments predicted future concussions among collegiate student-athletes. Participant cases (concussed = 2529; control = 30,905) completed preinjury: demographic forms (sport, concussion history, sex), Immediate Post-Concussion Assessment and Cognitive Test, Balance Error Scoring System, Sport Concussion Assessment Tool symptom checklist, Standardized Assessment of Concussion, Brief Symptom Inventory-18 item, Wechsler Test of Adult Reading, and Brief Sensation Seeking Scale. We used machine-learning logistic regressions with area under the curve, sensitivity, and positive predictive values statistics for univariable and multivariable analyses. Primary sport was determined to be the strongest univariable predictor (area under the curve = 64.3% ± 1.4, sensitivity = 1.1% ± 1.4, positive predictive value = 4.9% ± 6.5). The all-predictor multivariable model was the strongest (area under the curve = 68.3% ± 1.6, sensitivity = 20.7% ± 2.7, positive predictive value = 16.5% ± 2.0). Despite a robust sample size and novel analytical approaches, accurate concussion prediction was not achieved regardless of modeling complexity. The strongest positive predictive value (16.5%) indicated only 17 of every 100 individuals flagged would experience a concussion. These findings suggest preinjury characteristics or baseline assessments have negligible utility for predicting subsequent concussion. Researchers, healthcare providers, and sporting organizations therefore should not use preinjury characteristics or baseline assessments for future concussion risk identification at this time.

Primary and Secondary Risk Factors Associated With Concussion Symptom Clusters in Collegiate Athletes: Results From the NCAA-DoD Grand Alliance CARE Consortium.

Background: There is a broad and diverse range of symptoms after a concussion, from irritability to nausea. This heterogeneity of symptoms is a challenge for clinicians managing the different presentations among injuries. Prior research has investigated the structure of postconcussive symptoms to determine if they can be grouped into clusters of related symptoms. Purpose/Hypothesis: The purpose of this study was to identify symptom clusters during the acute phase after a sports-related concussion using exploratory factor analysis and to understand the relationship between risk factors for postconcussion symptoms (ie, demographics, injury characteristics, mental health, and sleep qualities) and different symptom clusters. We hypothesized that certain factors would be predictive of specific symptom clusters. Study Design: Cross-sectional study; Level of evidence, 3. Methods: Collegiate athletes (N = 1104) from the Concussion, Assessment, Research, and Education (CARE) Consortium completed the Sport Concussion Assessment Tool-Third Edition symptom assessment tool 24 to 48 hours after concussion. Exploratory factor analysis was conducted on the symptom evaluation to determine symptom clusters 24 to 48 hours after concussion. Regression analysis was used to examine the effects of pre- and postinjury characteristics. Results: Exploratory factor analysis revealed a 4-cluster structure for acute postconcussive symptoms that explained 62% of the variance in symptom reporting: vestibular-cognitive, migrainous, cognitive fatigue, and affective. Delayed reporting, less sleep before assessment, female sex, and being hurt outside of competition (during practice/training) was correlated with increased symptoms for 4 symptom clusters. Depression predicted higher vestibular-cognitive and affective symptoms. Amnesia was correlated with higher vestibular-cognitive and migrainous symptoms, whereas migraine history was associated with more migrainous and affective symptoms. Conclusion: Symptoms can be grouped into 1 of 4 distinct clusters. Certain variables were associated with increased symptoms across multiple clusters and may be indicative of greater injury severity. Other factors (ie, migraine history, depression, amnesia) were associated with a more specific symptom presentation and may be mechanistically related to concussion outcomes and biological markers.

Contact or Collision Sport History, Repetitive Neurotrauma, and Patient-Reported Outcomes in Early to Midadulthood.

CONTEXT: Data on the early to midlife effects of repetitive neurotrauma on patient-reported outcomes have been delimited to homogeneous samples of male athletes without comparison groups or accounting for modifying factors such as physical activity. OBJECTIVE: To determine the effect of contact or collision sport participation and repetitive neurotrauma on patient-reported outcomes among early to middle-aged adults. DESIGN: Cross-sectional study. SETTING: Research laboratory. PATIENTS OR OTHER PARTICIPANTS: A total of 113 adults (53 [46.9%] men, 60 [53.1%] women; age = 34.88 ± 11.80 years) in 4 groups: (1) physically inactive individuals with no repetitive head impact (RHI) exposure (NON); (2) noncontact sport athletes and nonathletes with no RHI exposure who were currently physically active (NCA); (3) former high-risk sport athletes with an RHI history who were physically active (HRS); and (4) former rugby players with prolonged RHI exposure who remained physically active. MAIN OUTCOME MEASURE(S): The 12-Item Short-Form Health Survey (SF-12), Apathy Evaluation Scale-self-rated version (AES-S), Satisfaction With Life Scale (SWLS), and Sport Concussion Assessment Tool-5th Edition (SCAT5) Symptom and Symptom Severity Checklist. RESULTS: The NON group had worse self-rated physical function than the NCA group as assessed by the SF-12 physical component summary (P = .03) and worse self-rated apathy (AES-S) and satisfaction with life (SWLS) than the NCA (P = .03 for both) and HRS groups (P = .03 and P = .040, respectively). We observed no group differences for self-rated mental health (SF-12 mental component summary; P = .26) or symptoms (SCAT5; P = .42). Career duration was not associated with any patient-reported outcomes. CONCLUSIONS: A history of contact or collision sport participation and career duration did not negatively affect patient-reported outcomes in physically active, early to middle-aged adults. However, physical inactivity status was negatively associated with patient-reported outcomes in these individuals in the absence of an RHI history.

Test-Retest Reliability and Efficacy of Individual Symptoms in Concussion Management.

OBJECTIVE: (1) To determine test-retest reliability of individual Sport Concussion Assessment Tool-Third Edition (SCAT-3) symptom scores and symptom severity scores, (2) to examine the specificity/sensitivity of individual SCAT-3 symptom severity scores acutely (24-48 hours) postconcussion, and (3) to develop a model of symptoms best able to differentiate concussed from nonconcussed student athletes and cadets. DESIGN: Prospective, longitudinal, and cross-sectional. SETTING: Twenty-six civilian schools and 3 US service academies. PARTICIPANTS: Collegiate student athletes (n = 5519) and cadets (n = 5359) from the National Collegiate Athletic Association-Department of Defense Grand Alliance: Concussion Assessment, Research and Education Consortium, including 290 student athletes and 205 cadets, assessed 24 to 48 hours postconcussion. INDEPENDENT VARIABLES: Concussed and nonconcussed student athlete and cadet groups. MAIN OUTCOME MEASURES: Sport Concussion Assessment Tool-Third Edition individual symptom severity scores, total symptom scores, and symptom severity scores. RESULTS: Results indicated poor test-retest reliability across all symptom scores (intraclass correlation coefficient = 0.029-0.331), but several individual symptoms had excellent predictive capability in discriminating concussed from nonconcussed participants (eg, headache, pressure in the head, and don't feel right had area under the curve >0.8, sensitivity >70%, and specificity >85%) regardless of baseline testing. These symptoms were consistent with Chi-square Automatic Interaction Detector classification trees with the highest mean probability. CONCLUSIONS: Findings support the excellent diagnostic accuracy of honest symptom reporting, notwithstanding the known limitations in symptom underreporting, and suggest that there may be added value in examining individual symptoms rather than total symptom scores and symptom severity scores alone. Finally, findings suggest that baseline testing is not necessary for interpreting postconcussion symptom scores.

Cognitive and Behavioral Outcomes in Male and Female NCAA Soccer Athletes across Multiple Years: A CARE Consortium Study.

PURPOSE: The purpose of this study was to determine changes in neurocognitive, psychosocial, and balance functioning in collegiate male and female soccer players across three consecutive years of baseline testing compared with a control group of noncontact athletes. METHODS: Generalized estimating equations were used to compare changes in annual, preseason baseline measures of neurocognitive function, neurobehavioral and psychological symptoms, and postural stability between collegiate soccer players ( n = 75; 51 [68%] female soccer players) and noncontact athletes ( n = 210; 133 [63%] female noncontact athletes) across three consecutive years. RESULTS: Among all participants, the group-time interaction was not significant for any outcome measures. Overall, soccer players reported lower (better) Brief Symptom Inventory 18 Depression ( P = 0.004, Exp(B) = 0.36, 95% confidence interval [CI] = 0.18-0.73), Global Severity Index ( P = 0.006, Exp(B) = 0.53, 95% CI = 0.33-0.84), and Post-Concussion Symptom Scale Symptom Severity ( P < 0.001, Exp(B) = 0.45, 95% CI = 0.22-0.95) scores than noncontact athletes. No other outcome measures were different between soccer players and noncontact athletes. CONCLUSIONS: Among collegiate athletes, soccer players report similar or better psychosocial functioning and symptom scores than noncontact athletes. Importantly, neurocognitive functioning, neurobehavioral and psychological symptoms, and postural stability do not worsen over time in collegiate soccer players relative to their noncontact counterparts. Our findings suggest that despite possible exposure to repetitive head impacts, collegiate soccer players do not exhibit changes in observable function and symptoms across multiple seasons.

Effects of contact/collision sport history on gait in early- to mid-adulthood.

BACKGROUND: To determine the effect of contact/collision sport participation on measures of single-task (ST) and dual-task (DT) gait among early- to middle-aged adults. METHODS: The study recruited 113 adults (34.88 ± 11.80 years, (mean ± SD); 53.0% female) representing 4 groups. Groups included (a) former non-contact/collision athletes and non-athletes who are not physically active (n = 28); (b) former non-contact/collision athletes who are physically active (n = 29); (c) former contact/collision sport athletes who participated in high-risk sports and are physically active (n = 29); and (d) former rugby players with prolonged repetitive head impact exposure history who are physically active (n = 27). Gait parameters were collected using inertial measurement units during ST and DT gait. DT cost was calculated for all gait parameters (double support, gait speed, and stride length). Groups were compared first using one-way analysis of covariance. Then a multiple regression was performed for participants in the high-risk sport athletes and repetitive head impact exposure athletes groups only to predict gait outcomes from contact/collision sport career duration. RESULTS: There were no significant differences between groups on any ST, DT, or DT cost outcomes (p > 0.05). Contact/collision sport duration did not predict any ST, DT, or DT cost gait outcomes. CONCLUSION: Years and history of contact/collision sport participation does not appear to negatively affect or predict neurobehavioral function in early- to mid-adulthood among physically active individuals.

Test-Retest reliability and preliminary reliable change estimates for Sway Balance tests administered remotely in community-dwelling adults.

Objective: Impaired balance and postural stability can occur with advanced age, following traumatic brain injury, in association with neurological disorders and diseases, and as the result of acute or chronic orthopedic problems. The remote assessment of balance and postural stability could be of value in clinical practice and research. We examined the test-retest reliability and reliable change estimates for Sway Balance Mobile Application tests (Sway Medical, Tulsa OK, USA) administered remotely from the participant's home. Method: Primarily young, healthy community-dwelling adults completed Sway Balance Mobile Application tests remotely on their personal mobile devices once per week for three consecutive weeks while being supervised with a video-based virtual connection. Sway Balance tests include five stances (i.e., feet together, tandem right foot forward, tandem left foot forward, single leg right foot, single leg left foot), which are averaged to compute a Sway Balance composite score from 0 to 100, with higher scores indicating better postural stability. We examined test-retest reliability (measured with intraclass correlation coefficients, ICCs) and preliminary reliable change estimates for 70%, 80%, and 90% confidence intervals. Results: Participants included 55 healthy adults (ages = 26.7 ± 9.9 years, interquartile range = 20-30, range = 18-58; 38 [69%] women). Test-retest reliability for the Sway Balance composite score across three weeks was.88. Test-retest reliability for individual stances ranged from 62 to 83 (all ps < 0.001). At the 80% confidence interval, preliminary reliable changes estimates were 9 points for the Sway Balance composite score. Conclusions: For a remote administration, test-retest reliability was moderate-to-good for all Sway Balance stances, as well as for the Sway Balance composite score. Reliable change estimates may allow clinicians to determine whether an improvement or decline in performance is greater than the expected improvement or decline due to measurement error in young adults.

Consensus Head Acceleration Measurement Practices (CHAMP): Origins, Methods, Transparency and Disclosure.

The use of head kinematic measurement devices has recently proliferated owing to technology advances that make such measurement more feasible. In parallel, demand to understand the biomechanics of head impacts and injury in sports and the military has increased as the burden of such loading on the brain has received focused attention. As a result, the field has matured to the point of needing methodological guidelines to improve the rigor and consistency of research and reduce the risk of scientific bias. To this end, a diverse group of scientists undertook a comprehensive effort to define current best practices in head kinematic measurement, culminating in a series of manuscripts outlining consensus methodologies and companion summary statements. Summary statements were discussed, revised, and voted upon at the Consensus Head Acceleration Measurement Practices (CHAMP) Conference in March 2022. This manuscript summarizes the motivation and methods of the consensus process and introduces recommended reporting checklists to be used to increase transparency and rigor of future experimental design and publication of work in this field. The checklists provide an accessible means for researchers to apply the best practices summarized in the companion manuscripts when reporting studies utilizing head kinematic measurement in sport and military settings.

Age of First Concussion and Cognitive, Psychological, and Physical Outcomes in NCAA Collegiate Student Athletes.

OBJECTIVE: Concussions are common among youth athletes and could disrupt critical neurodevelopment. This study examined the association between age of first concussion (AFC) and neurocognitive performance, psychological distress, postural stability, and symptoms commonly associated with concussion in healthy collegiate men and women student athletes. METHODS: Participants included 4267 collegiate athletes from various contact, limited-contact, and non-contact sports (1818 women and 2449 men) who completed baseline assessments as part of the Concussion Assessment, Research and Education (CARE) Consortium. Psychological distress was assessed with the Brief Symptom Inventory 18; neurocognitive performance was assessed with the Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT); symptoms commonly associated with concussion were assessed with the ImPACT Post-Concussion Symptom Scale; postural stability was assessed with the Balance Error Scoring System. Generalized linear models were used to examine the effects of AFC on clinical outcomes separately in men and women. RESULTS: Later AFC was associated with lower global (Exp(B) = 0.96, P = 0.001) and somatic (Exp(B) = 0.96, P = 0.002) psychological distress on the Brief Symptom Inventory 18 and faster ImPACT reaction time (B = - 0.003, P = 0.001) in women. AFC was not associated with any clinical outcomes in men. CONCLUSION: Younger AFC was associated with some differences in psychological distress and reaction time among women but not men; however, these results are likely not clinically meaningful. Sociodemographic disparities, pre-existing conditions, and sport type may impact clinical and cognitive outcomes in collegiate athletes more than concussion history. Future work should examine the relationship between AFC and lifespan-related outcomes.

Association Between Collision Sport Career Duration and Gait Performance in Male Collegiate Student-Athletes.

BACKGROUND: Investigations of estimated age of first exposure to repetitive head impacts from collision and contact sports have shown no associations with neurocognitive or neurobehavioral function at the collegiate level, but the effect of career duration may be a more comprehensive factor. Understanding whether longer career duration influences gait performance would provide insights into potential neurological impairment. PURPOSE: To examine the relationship between career duration of collision sports and single/dual-task gait performance in collegiate student-athletes. STUDY DESIGN: Cross-sectional study; Level of evidence, 3. METHODS: We recruited 168 male student-athletes from collision sports: football, lacrosse, ice hockey, and wrestling (mean ± SD age, 19.2 ± 1.3 years; height, 184.5 ± 7.2 cm; mass, 94.3 ± 15.9 kg; estimated age of first exposure, 8.6 ± 3.1 years; career duration, 10.6 ± 3.0 years). All participants completed a baseline single- and dual-task gait assessment before the start of their athletic season. Inertial measurement units were used to measure gait speed and stride length. During the dual task, participants were asked to perform working memory cognitive tasks while walking. The dependent variables were single/dual-task gait speed and stride length, cognitive accuracy, and dual-task cost. The relationship between career duration, analyzed as a continuous variable, and the dependent variables was analyzed using a linear regression. RESULTS: There were no significant associations between career duration and single-task gait speed (1.16 ± 0.16 m/s; ß = -0.004; P = .35; 95% CI = -0.012 to 0.004; η2 = 0.005) or dual-task gait speed (1.02 ± 0.17 m/s; ß = -0.003; P = .57; 95% CI = -0.011 to 0.006; η2 = 0.002). There were also no significant associations between career duration and single/dual-task stride length, cognitive accuracy, or dual-task cost. CONCLUSION: Career duration among collegiate collision sport athletes was not associated with single- or dual-task gait performance, suggesting that a greater exposure to repetitive head impacts is not detrimental to dynamic postural control at the college level. However, the effects of diminished gait performance over the lifetime remain to be elucidated.

Effects of Pre-Collegiate Sport Specialization on Cognitive, Postural, and Psychological Functions: Findings from the NCAA-DoD CARE Consortium.

BACKGROUND: Early sport specialization has been associated with an increased risk of musculoskeletal injuries and unfavorable psychological outcomes; however, it is unknown whether sport specialization is associated with worse cognitive, postural, and psychological functions in first-year collegiate student-athletes. METHODS: First-year collegiate multisport (MA) and single-sport (SA) student-athletes were identified using a pre-collegiate sport experience questionnaire. The cognitive, postural, and psychological functions were assessed by the Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT), Standardized Assessment of Concussion (SAC), Balance Error Scoring System (BESS), and Brief Symptom Inventory 18 (BSI-18). RESULTS: MA student-athletes performed higher in cognitive outcomes (e.g., higher ImPACT visual memory composite scores [ß = 0.056, p < 0.001]), but had higher psychological distress (e.g., higher BSI-18 global severity index [ß = 0.057, p < 0.001]) and no difference in postural stability (p > 0.05) than SA student-athletes. CONCLUSIONS: This study indicated first-year collegiate athletes with a history of sport specialization demonstrate lower cognitive performance but decreased psychological distress and no differences in static postural stability as compared to their MA counterparts. Future studies should consider involving different health measures to better understand the influence of sport specialization on overall physical and mental health.

Age of First Exposure to Contact and Collision Sports and Later in Life Brain Health: A Narrative Review.

A controversial theory proposes that playing tackle football before the age of 12 causes later in life brain health problems. This theory arose from a small study of 42 retired National Football League (NFL) players, which reported that those who started playing tackle football at a younger age performed worse on selected neuropsychological tests and a word reading test. The authors concluded that these differences were likely due to greater exposure to repetitive neurotrauma during a developmentally sensitive maturational period in their lives. Several subsequent studies of current high school and collegiate contact/collision sports athletes, and former high school, collegiate, and professional tackle football players have not replicated these findings. This narrative review aims to (i) discuss the fundamental concepts, issues, and controversies surrounding existing research on age of first exposure (AFE) to contact/collision sport, and (ii) provide a balanced interpretation, including risk of bias assessment findings, of this body of evidence. Among 21 studies, 11 studies examined former athletes, 8 studies examined current athletes, and 2 studies examined both former and current athletes. Although the literature on whether younger AFE to tackle football is associated with later in life cognitive, neurobehavioral, or mental health problems in former NFL players is mixed, the largest study of retired NFL players (N = 3,506) suggested there was not a significant association between earlier AFE to organized tackle football and worse subjectively experienced cognitive functioning, depression, or anxiety. Furthermore, no published studies of current athletes show a significant association between playing tackle football (or other contact/collision sports) before the age of 12 and cognitive, neurobehavioral, or mental health problems. It is important to note that all studies were judged to be at high overall risk of bias, indicating that more methodologically rigorous research is needed to understand whether there is an association between AFE to contact/collision sports and later in life brain health. The accumulated research to date suggests that earlier AFE to contact/collision sports is not associated with worse cognitive functioning or mental health in (i) current high school athletes, (ii) current collegiate athletes, or (iii) middle-aged men who played high school football. The literature on former NFL players is mixed and does not, at present, clearly support the theory that exposure to tackle football before age 12 is associated with later in life cognitive impairment or mental health problems.