Concussion History Moderates Trunk Motion and Lower Extremity Biomechanical Relationships During Jump Landing and Cutting.

Concussion history, trunk motion, and lower extremity biomechanics associate with musculoskeletal injury risk. We aimed to examine the interaction between concussion history and trunk motion as possible modifiable factors for injury risk biomechanics during jump landing and cutting. Division I female athletes (24 with, 20 without concussion history) performed jump landings and jump-to-cuts at 45° in the opposite direction of the landing limb. We used multiple linear regressions with interaction terms to examine ankle dorsiflexion angle, knee flexion and abduction angle, and external knee flexion and abduction moment. We observed a group by trunk flexion interaction for nondominant external knee flexion moment (P = .042) during jump landing. Concussion history associated with increased external knee flexion moment as trunk flexion increased. We observed a group by trunk flexion interaction for the dominant limb dorsiflexion angle (P = .044), and group by trunk lateral bending interactions for the dominant (P = .039) and nondominant limb (P = .016) external knee flexion moment during cutting. During cutting, concussion history associated with decreased dominant dorsiflexion angles as trunk flexion increased, and decreased dominant and nondominant external knee flexion moment as lateral bending toward the planted limb increased. Concussion history associated with atypical biomechanics as trunk flexion and lateral bending increased.

Lower Extremity Somatosensory Function Throughout Concussion Recovery: A Prospective Cohort Study.

OBJECTIVE: Balance impairments may suggest somatosensory disruption beyond concussion clinical recovery, but somatosensory subsystems have never been directly assessed. Our objective was to examine somatosensory function between individuals with a concussion and healthy matched-controls at acute (<7 days) and asymptomatic (<72 hours of being symptom-free) time points. SETTING: Laboratory. PARTICIPANTS: Participants with a concussion and matched controls ( n = 24; 58% male, age: 19.3 ± 1.1 years, mass: 70.3 ± 16.4 kg, height: 177.3 ± 12.7 cm). DESIGN: Prospective cohort. MAIN MEASURES: Somatosensory assessments on the dominant limb at both time points included: (1) plantar touch sensation threshold via Semmes-Weinstein monofilaments, (2) plantar pressure pain threshold via algometry, and (3) knee absolute passive joint repositioning (PJR) error via Biodex across 3 arcs (105°-75°, 30°-60°, 90°-45° knee-flexion). We used mixed-model analyses of variance, post hoc Tukey honestly significant difference t tests with mean difference, 95% CI, and Hedges' g effect sizes to examine outcomes. RESULTS: Touch sensation had a group effect with the concussion cohort needing 0.95 grams of force (gf) more relative to controls (95% CI: 0.03 to 1.87; P = .043). No touch sensation interaction was present, but medium and large effects were observed for greater gf needed among the concussed cohort at the acute (1.11 gf; 95% CI: 0.17 to 2.05; g = 0.96) and asymptomatic time points (0.79 gf; 95% CI: -0.15 to 1.73; g = 0.73). No plantar pressure pain threshold effects were observed ( P ≥ .311), with negligible pressure difference magnitudes at the acute (0.26 pound force [lbf]/cm 2 ; 95% CI: -1.54 to 2.06; g = 0.13) and medium magnitudes at the asymptomatic time points (0.99 lbf/cm 2 ; 95% CI: -0.81 to 2.80; g = 0.42) for the concussed cohort needing more pressure to detect pain. The 30° to 60° PJR had a time effect, with asymptomatic time point having 3.12° better accuracy (95% CI: 1.23° to 5.02; P = .002). The concussed cohort had small-to-medium magnitude differences relative to controls at the acute time point for PJR during 105° to 75° (0.89°; g = 0.30) and 90° to 45° (0.62°; g = 0.17), but not 30° to 60° (-1.75°; g = -0.40). CONCLUSIONS: Individuals with a concussion exhibited large effects for diminished plantar touch sensation and small to medium effects for inhibited plantar pressure pain sensation compared with controls, which may indicate altered somatosensory function. Negligible PJR differences suggest knee joint position sense is not altered post-concussion. Pre- and postconcussion examination is warranted to understand causal somatosensory mechanisms.

Quantifying head impact biomechanical differences between commonly employed cleaning levels: a critical research interpretation consideration.

INTRODUCTION: Wearable accelerometry devices quantify on-field frequency and severity of head impacts to further improve sport safety. Commonly employed post-data collection cleaning techniques may affect these outcomes. OBJECTIVE: Our purpose was to compare game impact rates and magnitudes between three different cleaning levels (Level-1: impacts recorded within start and end times, Level-2: impacts during pauses/breaks removed, Level-3: video verified) for male youth tackle football. METHODS: Participants (n = 23, age = 10.9 ± 0.3 yrs, height = 150.0 ± 8.3 cm, mass = 41.6 ± 8.4 kg) wore Triax SIM-G sensors throughout Fall 2019. Impact rates, ratios (IRRs), and 95% confidence intervals (95%CI) were used to compare levels. Random-effects general linear models were used to compare peak linear acceleration (PLA;g) and angular velocity (PAV;rads/s). RESULTS: Level-1 resulted in higher impact rates (4.57; 95%CI = 4.14-5.05) compared to Level-2 (3.09; 95%CI = 2.80-3.42; IRR = 1.48; 95%CI = 1.34-1.63) and Level-3 datasets (2.56; 95%CI = 2.30-2.85; IRR = 1.78; 95%CI = 1.60-1.98). Level-2 had higher impact rates compared to Level-3 (1.21; 95%CI = 1.08-1.35). Level-1 resulted in higher PAV than Level-2 and Level-3 (p < 0.001) datasets. PLA did not differ across datasets (p = 0.296). CONCLUSIONS: Head impact data should be filtered of pauses/breaks, and does not substantially differ outcome estimates compared to time-intensive video verification.

Jump Height and Hip Power Decrease During Cognitive Loading Regardless of Sex: Implications for Sport Performance Metrics.

ABSTRACT: Shumski, EJ, Lempke, LB, Johnson, RS, Oh, J, Schmidt, JD, and Lynall, RC. Jump height and hip power decrease during cognitive loading regardless of sex: implications for sport performance metrics. J Strength Cond Res 37(4): 793-798, 2023-Sex and cognitive loading separately influence jumping performance. However, it is unknown how cognitive loading influences jump performance and how sex and cognitive loading interact. The purpose of our study was to determine if an interaction existed between sex and cognitive loading for the dependent variables jump height, ground contact time, reactive strength index, vertical stiffness, impulse, and lower extremity joint power during a double limb drop vertical jump. Twenty-one male (23.2 ± 2.5 years, 180.8 ± 8.4 cm, 80.4 ± 10.2 kg) and 20 female (21.7 ± 1.0 years, 163.7 ± 8.2 cm, 61.2 ± 9.4 kg) physically active individuals participated. Subjects jumped from a 30 cm box placed 50% of their height away from 2 force plates under single-task and dual-task (serial 6s or 7s) conditions. Separate 2 × 2 analyses of variance were used for all dependent variables (α = 0.05) with Bonferroni post hoc mean differences and 95% confidence intervals (CIs). There were no significant interactions for any outcomes ( p ≥ 0.190). Condition main effects demonstrated subjects jumped significantly higher (1.84 cm, 95% CI = 0.68-3.01, d = 0.26, p = 0.003) and with greater hip power (0.29 Watts·BW -1 ·HT -1 , 95% CI = 0.04-0.54, d = 0.21, p = 0.025) during single task compared with dual task. Sex main effects revealed males jumped higher (9.88 cm, 95% CI = 7.00-12.77, d = 2.17, p < 0.001), with greater reactive strength index (0.29, 95% CI = 0.17-0.41, d = 1.52, p < 0.001), greater ankle power (3.70 Watts·BW -1 ·HT -1 , 95% CI = 2.26-5.13, d = 1.64, p < 0.001), and greater knee power (5.00 Watts·BW -1 ·HT -1 , 95% CI = 3.25-6.75, d = 1.82, p < 0.001) compared with females. Jump performance is influenced by sex and dual-task conditions but not their interaction. To optimize jumping performance, testing should be completed without distractions (single task) to decrease cognitive loading.

Lower-Extremity Neuromuscular Function Following Concussion: A Preliminary Examination.

CONTEXT: Neuromuscular function is altered acutely following concussion and theoretically linked to the subsequent postconcussion musculoskeletal injury risk. Existing research has only examined voluntary muscle activation, limiting mechanistic understanding. Therefore, our study aimed to examine voluntary and involuntary muscle activation between college-aged, concussed individuals when symptom-free and healthy matched controls. DESIGN: Prospective, cross-sectional cohort laboratory study. METHODS: Concussed and healthy participants (n = 24; 58% male, age: 19.3 [1.1] y, mass: 70.3 [16.4] kg, height: 177.3 [12.7] cm) completed the superimposed burst (SB) neuromuscular assessment on their dominant limb within 72 hours after self-reporting asymptomatic (22.4 [20.2] d postinjury). Unnormalized and bodyweight-normalized quadriceps maximal voluntary isometric contraction torque (in newton meters), unnormalized and bodyweight-normalized electrically stimulated SB torque, pain (numeric 1-10) during SB, and the central activation ratio (in percentage) were assessed via the SB. Parametric and nonparametric analyses, 95% confidence intervals (95% CIs), and Hedges g (parametric) and Spearman ρ (nonparametric) effect sizes were used to examine group differences (α = .05). RESULTS: The maximal voluntary isometric contraction torque (concussed: 635.60 N·m [300.93] vs control: 556.27 N·m [182.46]; 95% CI, -131.36 to 290.02; P = .443; d = 0.33), SB torque (concussed: 203.22 N·m [97.17], control: 262.85 N·m [159.07]; 95% CI, -171.22 to 51.97; P = .280; d = -0.47), and central activation ratio (concussed: 72.16% [17.16], control: 70.09% [12.63]; 95% CI, -10.68 to 14.83; P = .740; d = 0.14) did not differ between the concussed and control groups regardless of bodyweight normalization (P ≥ .344). Pain during the SB was significantly higher with a medium effect for participants with a concussion versus healthy controls (concussed: median = 7, control: median = 5; P = .046; ρ = -0.42). DISCUSSION: These findings suggest concussed participants do not have statistically altered voluntary or involuntary quadricep neuromuscular function once asymptomatic compared with controls. Therefore, the elevated postconcussion musculoskeletal injury risk may not be attributed to lower-extremity muscle activation. Concussed participants displayed greater pain perception during the SB, which suggests somatosensory or perception changes requiring further examination.

Single-Leg Hop Stabilization Throughout Concussion Recovery: A Preliminary Biomechanical Assessment.

CONTEXT: Aberrant movement patterns among individuals with concussion history have been reported during sport-related movement. However, the acute postconcussion kinematic and kinetic biomechanical movement patterns during a rapid acceleration-deceleration task have not been profiled and leaves their progressive trajectory unknown. Our study aimed to examine single-leg hop stabilization kinematics and kinetics between concussed and healthy-matched controls acutely (≤7 d) and when asymptomatic (≤72 h of symptom resolution). DESIGN: Prospective, cohort laboratory study. METHODS: Ten concussed (60% male; 19.2 [0.9] y; 178.7 [14.0] cm; 71.3 [18.0] kg) and 10 matched controls (60% male; 19.5 [1.2] y; 176.1 [12.6] cm; 71.0 [17.0] kg) completed the single-leg hop stabilization task under single and dual task (subtracting by 6's or 7's) at both time points. Participants stood on a 30-cm tall box set 50% of their height behind force plates while in an athletic stance. A synchronized light was illuminated randomly, queuing participants to initiate the movement as rapidly as possible. Participants then jumped forward, landed on their nondominant leg, and were instructed to reach and maintain stabilization as fast as possible upon ground contact. We used 2 (group) × 2 (time) mixed-model analyses of variance to compare single-leg hop stabilization outcomes separately during single and dual task. RESULTS: We observed a significant main group effect for single-task ankle plantarflexion moment, with greater normalized torque (mean difference = 0.03 N·m/body weight; P = .048, g = 1.18) for concussed individuals across time points. A significant interaction effect for single-task reaction time indicated that concussed individuals had slower performance acutely relative to asymptomatic (mean difference = 0.09 s; P = .015, g = 0.64), while control group performance was stable. No other main or interaction effects for single-leg hop stabilization task metrics were present during single and dual task (P ≥ .051). CONCLUSIONS: Greater ankle plantarflexion torque coupled with slower reaction time may indicate stiff, conservative single-leg hop stabilization performance acutely following concussion. Our findings shed preliminary light on the recovery trajectories of biomechanical alterations following concussion and provide specific kinematic and kinetic focal points for future research.

Association between sports participation history and age of first exposure to high-risk sports with concussion history.

The purpose of this study was to examine the association between sports participation history, including estimated age of first exposure (eAFE) to high-risk sports, and concussion history in first year (i.e., freshmen) collegiate athletes. Athletes increased their odds of sustaining a pre-college concussion by 5% [odds ratio(OR) = 1.05 (95%CI:1.05-1.06)] for each additional year of contact sports participation - 24% of all student athletes reported one or more pre-college concussions. When eAFE was analysed dichotomously at age 12, a greater proportion of those who started playing football before age 12 reported a positive concussion history compared to those who started playing football at age 12 or later (Ð¥2 = 4.483, p = 0.034, Phi = 0.049). When eAFE was analysed continuously, later eAFE to women's high-risk sports was associated with a lower likelihood of sustaining a pre-college concussion [OR = 0.93 (95%CI:0.88-0.98)]. Our findings suggest that there is a relationship between eAFE to football and to women's high-risk sports and concussion history.

Concussion Characteristics and Early Postinjury Outcomes Between College Students and Intercollegiate Athletes.

OBJECTIVE: To describe concussion characteristics among general college students and compare postinjury outcomes to intercollegiate student athletes. DESIGN: Retrospective cohort. SETTING: Large university in the Southeast region of the United States. PARTICIPANTS: A total of 179 (N=179) college students' (female=120; 67.0%; 23.9±3.9 years) and 49 athletes' (female=28, 57.1%;19.3±1.3 years) medical records were examined. Participants self-reported injury mechanism, health history information, and completed clinical assessments acutely (<7 days postinjury). MAIN OUTCOME MEASURES: Descriptive statistics were calculated for each group. Concussion outcomes between students with and without certain health history diagnoses were assessed using separate t tests. We conducted univariate regression analyses to determine if sex, age, and time from concussion to first clinical assessment were significant predictors of clinical outcomes. Statistically significant variables were included as covariates in a series of 1-way analyses of covariance to identify differences in balance, symptom severity, total symptom presence, and neurocognitive domain performance between students and athletes. Fisher exact tests were used to compare health history information between groups (α<0.05). RESULTS: Among students, 24% reported sustaining a concussion while participating in recreational sports, and 27% of impacts occurred to the back of the head. Students had higher proportions of headache, migraine, anxiety, and depression (P<.05). Students reported greater total symptom presence (P=.006) and performed worse on the computerized neurocognitive test domain score for complex attention (P=.015) relative to athletes. CONCLUSIONS: These findings highlight the need for better access to medical care for non- National Collegiate Athletic Association sanctioned athletes because of a large proportion of concussions in the student sample being sustained during sports participation. Identifying common injury mechanisms can provide clinicians with powerful information to improve evaluation and treatment models.

Concussion reporting intentions for incoming military athletes and cadets.

Cultures of concussion reporting exist outside athletics; however, athlete-only studies dominate the literature. Comparing athletes and similar high-risk populations broadens our understanding of concussion reporting acculturation. We aimed to (1) describe and compare concussion self-report willingness as measured by anticipated concussion reporting (ACR), perceived costs, perceived rewards, brain health knowledge, and correct symptom identification for incoming cadets at the United States Air Force Academy (USAFA) (n = 1,136; female = 276, 24.43%) and (2) determine whether those variables predict ACR. Univariate analyses were performed to compare intercollegiate status, sex, and parental income for perceived costs and rewards, and brain health knowledge (α = 0.05) and multinomial logistic regressions to determine if those variables predicted ACR. A $40,000 parental increase in income resulted in one additional symptom identified (ß = 0.80, p = 0.026). Athletes demonstrated greater brain health knowledge by nearly one symptom correctly identified (ß = 0.98, p = 0.002); non-athletes reported significantly greater ACR (ß = 5.92; p < 0.001). Our model accounted for 37% of the variance in ACR (χ2 = 393.86, p < 0.001, Nagelkerke R2 = 0.37). Before military acculturation, athletes had less intention to seek medical care for concussion, likely from prior athletic experiences.

Under-representation of female athletes in research informing influential concussion consensus and position statements: an evidence review and synthesis.

OBJECTIVE: We aimed to quantify the female athlete composition of the research data informing the most influential consensus and position statements in treating sports-related concussions. DESIGN: We identified the most influential concussion consensus and position statements through citation and documented clinician use; then, we analysed the percentage of male and female athletes from each statement's cited research. DATA SOURCES: We searched PubMed on 26 August 2021 with no date restrictions for English language studies using the terms 'concussion position statement' and 'concussion consensus statement.' ELIGIBILITY CRITERIA FOR SELECTING STUDIES: Based on each statement having multiple statement editions, documented clinician use, and substantial citation advantages, we selected the National Athletic Trainers' Association (NATA, 2014), International Conference on Concussion in Sport (ICCS, 2017) and the American Medical Society for Sports Medicine (AMSSM, 2019). We extracted all cited studies from all three papers for assessment. For each paper analysing human data, at least two authors independently recorded female athlete participant data. RESULTS: A total of 171 distinct studies with human participants were cited by these three consensus and position papers and included in the female athlete analyses (93 NATA; 13 ICCS; 65 AMSSM). All three statements documented a significant under-representation of female athletes in their cited literature, relying on samples that were overall 80.1% male (NATA: 79.9%, ICCS: 87.8 %, AMSSM: 79.4%). Moreover, 40.4% of these studies include no female participants at all. CONCLUSION: Female athletes are significantly under-represented in the studies guiding clinical care for sport-related concussion for a broad array of sports and exercise medicine clinicians. We recommend intentional recruitment and funding of gender diverse participants in concussion studies, suggest authorship teams reflect diverse perspectives, and encourage consensus statements note when cited data under-represent non-male athletes.

Number of prior concussions predict poorer concussion care seeking in military cadets.

PRIMARY OBJECTIVE: To determine whether concussion history predicts concussion care seeking, self-management practices, or confidence to recognize/report. RESEARCH DESIGN: Cross-sectional. METHODS & PROCEDURES: 706 United States Air Force Academy (USAFA) cadets completed survey items regarding concussion history (0,1,2,3+), likelihood of reporting a concussion, self-management, and confidence to recognize/report. We used multivariate ordinal and binary logistic regression models to predict responses using concussion history, sex, and race.Main outcomes & results: cadets with 1 (OR = 0.59, 95%CI:0.43-0.82), 2 (OR = 0.55, 95%CI:0.31-0.98), or 3+ (OR = 0.36, 95%CI:0.17-0.78) concussions while at USAFA had respective 41%, 45%, and 64% lower likelihood to report the concussion scenario (ref = no history, p < .001). USAFA cadets with more extensive concussion histories had higher prevalence of not seeking care for a concussion (p < .001); more strongly endorsed self-management (p = .001-0.010); and had greater confidence in their ability to recognize a concussion (p = .005), but not to report (p = .198-0.413). CONCLUSIONS: Prior concussion experiences may deter cadets from seeking medical care for future concussions. Interventions should address concussion history and clinicians should consider how the post-concussion management process might deter care seeking.

The Influence of Socioeconomic Status and Academic Standing on Concussion-Reporting Intentions and Behaviors in Collegiate Athletes.

Concussion education have served as a keystone for improving concussion reporting. Numerous factors affecting concussion reporting have been explored; however, the role of socioeconomic status (SES) in reporting has not been established. We examined the influence of SES and academic achievement (high-school grade point average [HS-GPA] and American College Testing [ACT] composite scores) on athletes' concussion-reporting intentions and behaviors. A cross-sectional study was employed among 191 athletes (94 female; age 19.3 ± 1.2 years). Athletes reported SES metrics (parental education and occupation, household income, HS-GPA, and ACT composite score) prior to their athletic season and completed a survey assessing symptom- and concussion-reporting intentions. Symptom- and concussion-reporting behaviors were assessed among athletes who experienced a concussion within the past year. SES was determined using the Hollingshead Four-Factor Index grouping athletes into SES strata. Athletes were grouped into low/high categories for academic achievement and household income variables. The 191 athletes were included for symptom- and concussion-reporting intentions analyses, while 46 and 41 were included for symptom- and concussion-reporting behavior, respectively. Nonparametric statistics with false discovery rate adjusted p values were employed. We found symptom- and concussion-reporting intentions, and symptom- and concussion-reporting behaviors were not significantly different based on SES strata (all p values ≥.64), household income (all p values ≥.64), HS-GPA (all p values ≥.24), or ACT scores (all p values ≥.25). Overall, SES and academic achievement may not play a role in understanding concussion reporting among middle- to high-SES collegiate athletes. Implementing policies targeting certain SES and academic levels might be an ineffective health care strategy for increasing reporting.

Test-Retest Reliability of a Functional Reaction Time Assessment Battery.

CONTEXT: Reaction time is commonly assessed postconcussion through a computerized neurocognitive battery. Although this measure is sensitive to postconcussion deficits, it is not clear if computerized reaction time reflects the dynamic reaction time necessary to compete effectively and safely during sporting activities. Functional reaction time assessments may be useful postconcussion, but reliability must be determined before clinical implementation. OBJECTIVE: To determine the test-retest reliability of a functional reaction time assessment battery and to determine if reaction time improved between sessions. DESIGN: Cohort. SETTING: Laboratory. PARTICIPANTS: Forty-one participants (21 men and 20 women) completed 2 time points. Participants, on average, were 22.5 (2.1) years old, 72.5 (11.9) cm tall, had a mass of 71.0 (13.7) kg, and were mostly right leg and hand dominant (92.7%). INTERVENTIONS: Participants completed 2 clinical reaction time tests (computerized Stroop and drop stick) and 5 functional reaction time tests (gait, jump landing, single-leg hop, anticipated cut, and unanticipated cut) across 2 sessions. Drop stick and functional reaction time assessments were performed in single (motor task only) and dual task (motor task with cognitive task). MAIN OUTCOME MEASURES: Reaction time (in seconds) was calculated during all assessments. Test-retest reliability was determined using 2-way mixed-effects intraclass correlation coefficients (3, k). Paired samples t tests compared mean reaction time between sessions. RESULTS: Test-retest reliability was moderate to excellent for all reaction time outcomes (intraclass correlation coefficients [3, k] range = .766-.925). Several statistically significant between-session mean differences were observed, but effect sizes were negligible to small (d range = 0.05-0.44). CONCLUSIONS: The functional reaction time assessment battery displayed similar reliability to the standard computerized reaction time assessment battery and may provide important postinjury information, but more research is needed to determine clinical utility.

Single- Versus Dual-Task Functional Movement Paradigms: A Biomechanical Analysis.

CONTEXT: Laboratory-based movement assessments are commonly performed without cognitive stimuli (ie, single-task) despite the simultaneous cognitive processing and movement (ie, dual task) demands required during sport. Cognitive loading may critically alter human movement and be an important consideration for truly assessing functional movement and understanding injury risk in the laboratory, but limited investigations exist. OBJECTIVE: To comprehensively examine and compare kinematics and kinetics between single- and dual-task functional movement among healthy participants while controlling for sex. DESIGN: Cross-sectional study. SETTING: Laboratory. Patients (or Other Participants): Forty-one healthy, physically active participants (49% female; 22.5 ± 2.1 y; 172.5 ± 11.9 cm; 71.0 ± 13.7 kg) enrolled in and completed the study. INTERVENTION(S): All participants completed the functional movement protocol under single- and dual-task (subtracting by 6s or 7s) conditions in a randomized order. Participants jumped forward from a 30-cm tall box and performed (1) maximum vertical jump landings and (2) dominant and (3) nondominant leg, single-leg 45° cuts after landing. MAIN OUTCOME MEASURES: The authors used mixed-model analysis of variances (α = .05) to compare peak hip, knee, and ankle joint angles (degrees) and moments (N·m/BW) in the sagittal and frontal planes, and peak vertical ground reaction force (N/BW) and vertical impulse (Ns/BW) between cognitive conditions and sex. RESULTS: Dual-task resulted in greater peak vertical ground reaction force compared with single-task during jump landing (mean difference = 0.06 N/BW; 95% confidence interval [CI], 0.01 to 0.12; P = .025) but less force during dominant leg cutting (mean difference = -0.08 N/BW; 95% CI, -0.14 to -0.02; P = .015). Less hip-flexion torque occurred during dual task than single task (mean difference = -0.09 N/BW; 95% CI, -0.17 to -0.02). No other outcomes were different between single and dual task (P ≥ .053). CONCLUSIONS: Slight, but potentially important, kinematic and kinetic differences were observed between single- and dual-task that may have implications for functional movement assessments and injury risk research. More research examining how various cognitive and movement tasks interact to alter functional movement among pathological populations is warranted before clinical implementation.

Using the health belief model to predict concussion-reporting intentions and behaviour.

PURPOSE: To determine whether Health Belief Model (HBM) factors predict concussion-reporting intentions and behaviour. Methods: Participants completed a cross-sectional survey to measure the HBM constructs of concussion knowledge, perceived susceptibility, perceived severity, perceived benefits, perceived barriers, and cues to action. We also asked participants to indicate their concussion-reporting intentions and behaviourfor symptom and concussion reporting. Four separate multivariable regressions were conducted to predict concussion-reporting intentions and behaviour based on HBM constructs. Results: Cues to action (ß = 0.25, p= .016) predicted symptom reporting intentions (F7,318 = 4.44, p< .001, R2 = 0.089), while perceived benefits (ß = 0.12, p= .018), perceived barriers (ß = -0.11, p= .034) and cues to action (ß = 0.29, p< .001) predicted concussion-reporting intentions (F7,318 = 11.34, p < .001, R2 = 0.200). The HBM did not predict symptom or concussion-reporting behavior (symptom: Χ2 = 5.51, p= .138, Nagelkerke R2 = 0.096; concussion: Χ2 = 5.20, p= .157, Nagelkerke R2 = 0.159). Conclusions: Strategies to reduce perceived barriers and increase benefits of reporting concussion symptoms may improve reporting intentions. This may include cues to action in sharing a positive view toward long-term health and dispelling that reporting a concussion would let down teammates. .

Improving concussion education: consensus from the NCAA-Department of Defense Mind Matters Research & Education Grand Challenge.

Early disclosure of possible concussive symptoms has the potential to improve concussion-related clinical outcomes. The objective of the present consensus process was to provide useful and feasible recommendations for collegiate athletic departments and military service academy leaders about how to increase concussion symptom disclosure in their setting. Consensus was obtained using a modified Delphi process. Participants in the consensus process were grant awardees from the National Collegiate Athletic Association and Department of Defense Mind Matters Research & Education Grand Challenge and a multidisciplinary group of stakeholders from collegiate athletics and military service academies. The process included a combination of in-person meetings and anonymous online voting on iteratively modified recommendations for approaches to improve concussion symptom disclosure. Recommendations were rated in terms of their utility and feasibility in collegiate athletic and military service academy settings with a priori thresholds for retaining, discarding and revising statements. A total of 17 recommendations met thresholds for utility and feasibility and are grouped for discussion in five domains: (1) content of concussion education for athletes and military service academy cadets, (2) dissemination and implementation of concussion education for athletes and military service academy cadets, (3) other stakeholder concussion education, (4) team and unit-level processes and (5) organisational processes. Collectively, these recommendations provide a path forward for athletics departments and military service academies in terms of the behavioural health supports and institutional processes that are needed to increase early and honest disclosure of concussion symptoms and ultimately to improve clinical care outcomes.

Influence of Postconcussion Sleep Duration on Concussion Recovery in Collegiate Athletes.

OBJECTIVE: To determine whether decreased sleep duration postconcussion influences days to asymptomatic and assessment of performance throughout recovery. DESIGN: Prospective. SETTING: Institutional Clinical Research Laboratory. PATIENTS: Four hundred twenty-three collegiate athletes were diagnosed with concussion. INTERVENTIONS: Multidimensional concussion assessment battery was conducted at baseline, within 24 to 48 hours, daily [2-4 days postinjury (PI); symptoms only], once asymptomatic, and after return-to-play. The battery included the following: 22-item symptom checklist, Standardized Assessment of Concussion (SAC), Balance Error Scoring System (BESS), and computerized neurocognitive test [Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT)]. MAIN OUTCOME MEASURES: We subtracted baseline sleep duration from 24 to 48 hours postconcussion sleep duration and categorized athletes into the following groups: shorter sleep (≤-1 hour), no change (>-1 hour, <+1 hour), and longer sleep (≥+1 hour). A 1-way analysis of variance (ANOVA) was conducted to compare days to asymptomatic and separate mixed-model ANOVAs to compare total symptom scores, SAC total scores, BESS total error scores, and ImPACT composite scores between sleep categories across time points (α = 0.05). RESULTS: Sleep groups did not differ in days to asymptomatic. The shorter sleep group had greater symptom severity than no sleep change and longer sleep groups at 24 to 48 hours (shorter: 39.1 ± 20.7; no change: 25.1 ± 18.4, P = 0.007; longer: 25.7 ± 21.8, P = 0.004), and at 2 to 4 days PI (shorter: 21.8 ± 21.8; no change: 10.5 ± 10.8, P = 0.013; longer: 11.9 ± 14.2, P = 0.007), but did not differ at other time points (ie, asymptomatic and return-to-play). Participants with shorter sleep exhibited slower ImPACT reaction times at 24 to 48 hours (shorter: 0.68 ± 0.14; no change: 0.61 ± 0.09, P = 0.016; and longer: 0.62 ± 0.12, P = 0.028) and asymptomatic time points (shorter: 0.62 ± 0.11; no change: 0.56 ± 0.05; P = 0.015). CONCLUSION: Postinjury sleep declines may be associated with symptom severity and worsened reaction time during initial stages of recovery or may be the result of the concussion itself. Clinicians should be aware of alterations in sleep duration and manage appropriately to mitigate initial symptom burden postconcussion.

King-Devick Test Time Varies by Testing Modality.

OBJECTIVE: To explore differences in baseline King-Devick Test (KD) completion time between 2 testing modalities: (1) spiral-bound paper cards (cards) and (2) iPad application (iPad). DESIGN: Cross-sectional cohort analysis. SETTING: National Collegiate Athlete Association (NCAA) institutions. PARTICIPANTS: Student athletes from 13 women's and 11 men's collegiate sports who completed KD baseline testing as part of their first year in the Concussion Assessment, Research and Education (CARE) Consortium from 2014 to 2016 (n = 2003, 52.2% male). INDEPENDENT VARIABLES: King-Devick Test modalities; cards or iPad. MAIN OUTCOME MEASURE: Baseline KD completion time (seconds). RESULTS: Mean baseline KD completion time of the iPad modality group [42.8 seconds, 95% confidence interval (CI), 42.1-43.3] was 2.8 seconds (95% CI, 2.1-3.4) greater than the cards group (40.0 seconds, 95% CI, 39.7-40.3) (t(1, 1010.7) = -8.0, P < 0.001, Cohen's d = 0.41). CONCLUSIONS: Baseline KD performance is slower when tested on an iPad than when tested on spiral-bound paper cards. The 2 KD modalities should not be used interchangeably in concussion assessments because differences in the modalities can lead to time differences similar in magnitude to those used to indicate concussion. From a research perspective, modality may influence interpretation and/or synthesis of findings across studies.

Effects of College Athlete Life Stressors on Baseline Concussion Measures.

CONTEXT: Concussion baseline testing helps injury evaluation by allowing postinjury comparisons to preinjury measures. To facilitate best practice, common neurocognitive, balance, and symptom report metrics used in concussion baseline testing merit examination relative to participant life stressors. OBJECTIVE: The purpose of this study was to determine if life stressors are associated with college athlete neurocognitive function, postural control, and symptom scores at preseason baseline assessment. DESIGN: All study variables were collected in a single laboratory session where athletes completed valid and reliable psychometrics as well as a computerized neurocognitive and balance assessments. SETTING: Sports medicine research center on an American university campus. PARTICIPANTS: A convenience sample of 123 college student-athletes: 47 females (age = 18.9 [4.3] y) and 76 males (age = 19.4 [1.6] y). MAIN OUTCOME MEASURES: Participants were categorized into low, moderate, or high life stressors groups using scores from the Social Readjustment Rating Scale-Revised. Dependent variables included outcomes from the CNS Vitals Signs test, the Sensory Organization Test, and the graded symptom checklist indexing neurocognition, balance, and symptom severity, respectfully. RESULTS: One-way analysis of variance revealed that the moderate life stressors group performed significantly worse than the low life stressors group on the baseline verbal memory domain of the CNS Vital Signs (F2,119 = 3.28; P = .04) only. CONCLUSION: In the current college athlete sample, few baseline concussion assessment variables were found to be significantly associated with life stressors. Considering the clinical significance of these variables, psychological life stressors may not be a confounding factor in concussion evaluation.

Post-concussion driving management among athletic trainers.

Primary objective: To describe and compare athletic trainer (AT) post-concussion driving management practices and opinions.Research design: Cross-sectional.Methods & procedures: A survey was sent via email to 8,723 ATs (10.8% response rate[945/8723]) to capture demographics, management practices, and opinions (agreement on a seven-point Likert scale). We used Kruskal-Wallis tests to compare the percentage of patients instructed to refrain from driving across the highest earned a degree, setting, and years certified (alpha = 0.05).Main outcomes & results: When asked whether they recommended patients with concussion refrain from driving, 58.5%(n = 553/945) of ATs responded "sometimes", 37.9%(n = 358/945) responded "always", and 3.6%(n = 34/945) responded "never". ATs responding "sometimes" or "always" estimated that they instruct 57.6 ± 37.6% of patients with concussion to refrain from driving. ATs most commonly: recommended that patients refrain from driving until symptom resolution(44.7%,n = 399/892); utilized their clinical exam (patient interview/history) to determine when a patient could resume driving(64.9%,n = 579/892); and provided instructions verbally(94.2%,n = 840/892). High school(60.5 ± 37.6%) and clinical ATs(66.5 ± 31.2%) trended toward higher percentages of patients they instruct to refrain from driving relative to college(52.3 ± 38.2%; χ2(2) = 5.92,p = .052).Conclusions: ATs recommend driving restrictions to some, but not all, patients with concussion. Overall, ATs recognize post-concussion driving dangers, but do not strongly endorse refraining from driving after a concussion. High school and clinical ATs may manage more adolescent novice drivers and, therefore, act more conservatively.