Minimum detectable change and false positive rates of the vestibular/ocular motor screening (VOMS) tool: an NCAA-DoD care consortium analysis.

OBJECTIVE: To derive minimum detectable change (MDC) across individual Vestibular-Ocular Motor Screening (VOMS) items and VOMS overall score in 17-25 years old collegiate athletes and to examine false positive rates. METHOD: Participants (n = 378) completed VOMS pre-season for two consecutive years. MDC was identified for individual VOMS symptom items and NPC distance (cm). Both total and change methods of VOMS scoring were included in analysis. RESULTS: Regarding total scoring, MDC for ocular VOMS symptom items was 1 and MDC for vestibular VOMS symptoms items was 2. MDC for NPC was 4 cm and for VOMS overall score was 10. Regarding change scoring, MDC for each VOMS symptom item was 1, and for VOMS overall score was 8. False positives ranged from 5.3% to 15.9%. CONCLUSIONS: This study presents MDCs for each VOMS item and overall VOMS score, using total and change scoring. These values can be considered true change outside measurement error with 95% confidence in a 17-25 year old collegiate athlete population.

Bicycling Exercise Helps Maintain a Youthful Metabolic Cost of Walking in Older Adults.

The decline of walking performance is a key determinant of morbidity among older adults. Healthy older adults have been shown to have a 15-20% lower walking economy compared with young adults. However, older adults who run for exercise have a higher walking economy compared with older adults who walk for exercise. Yet, it remains unclear if other aerobic exercises yield similar improvements on walking economy. The purpose of this study was to determine if regular bicycling exercise affects walking economy in older adults. We measured metabolic rate while 33 older adult "bicyclists" or "walkers" and 16 young adults walked on a level treadmill at four speeds between (0.75-1.75 m/s). Across the range of speeds, older bicyclists had a 9-17% greater walking economy compared with older walkers (p = .009). In conclusion, bicycling exercise mitigates the age-related deterioration of walking economy, whereas walking for exercise has a minimal effect on improving walking economy.

Concussion Symptoms Among Athletes: Preinjury Factors Predict Postinjury Factors.

OBJECTIVE: Determine whether preinjury concussion symptom factors predict postinjury concussion symptom factors. SETTING: Community concussion surveillance program between 2008 and 2017. PARTICIPANTS: A total of 290 high school and collegiate-aged athletes (n = 168, aged 14-17 years; n = 122, aged 18-21 years, respectively). DESIGN: Retrospective analysis. MAIN MEASURES: Post-Concussion Symptom Scale scores prior to and within 7 days of sustaining a sport-related concussion. METHODS: Post-Concussion Symptom Scale scores were aggregated into cognitive-sensory, sleep-arousal, vestibular-somatic, and affective preinjury symptom factors. These preinjury symptom factors, in conjunction with sex and previous concussion history, underwent linear regressions to predict cognitive-migraine-fatigue, somatic, sleep, and affective postinjury symptom factors. RESULTS: The cognitive-sensory factor (P = .002) and female sex (P = .002) predicted the postinjury cognitive-migraine-fatigue factor in combined age group but not stratified age group models. Among the 14 to 17 years age group, and not the 18 to 21 years age group, the preinjury sleep-arousal symptom factor predicted postinjury somatic (P = .003) and sleep factors (P = .005). The affective preinjury factor predicted the affective factor (P = .001) and somatic factor (P = .008) in the 18 to 21 years age group. A history of previous concussions also predicted the postinjury somatic symptom factor (P = .005). CONCLUSION: Preinjury symptom factors predicted postinjury symptom factors and age-associated differences in symptom factors may provide clinical value in prognostic models for subsequent postinjury clinical outcomes.

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.

Muscle force, work and cost: a novel technique to revisit the Fenn effect.

Muscle produces force by forming cross-bridges, using energy released from ATP. While the magnitude and duration of force production primarily determine the energy requirement, nearly a century ago Fenn observed that muscle shortening or lengthening influenced energetic cost of contraction. When work is done by the muscle, the energy cost is increased and when work is done on the muscle the energy cost is reduced. However, the magnitude of the 'Fenn effect' and its mirror ('negative Fenn effect') have not been quantitatively resolved. We describe a new technique coupling magnetic resonance spectroscopy with an in vivo force clamp that can directly quantify the Fenn effect [E=I+W, energy liberated (E) equals the energy cost of isometric force production (I) plus the work done (W)] and the negative Fenn effect (E=I-W) for one muscle, the first dorsal interosseous (FDI). ATP cost was measured during a series of contractions, each of which occurred at a constant force and for a constant duration, thus constant force-time integral (FTI). In all subjects, as the FTI increased with load, there was a proportional linear increase in energy cost. In addition, the cost of producing force greatly increased when the muscle shortened, and was slightly reduced during lengthening contraction. These results, though limited to a single muscle, contraction velocity and muscle length change, do quantitatively support the Fenn effect. We speculate that they also suggest that an elastic element within the FDI muscle functions to preserve the force generated within the cross-bridges.

The effect of forward postural lean on running economy, kinematics, and muscle activation.

BACKGROUND: Running economy, commonly defined as the metabolic energy demand for a given submaximal running speed, is strongly associated with distance running performance. It is commonly believed among running coaches and runners that running with increased forward postural lean either from the ankle or waist improves running economy. However, recent biomechanical research suggests using a large forward postural lean during running may impair running economy due to increased demand on the leg muscles. PURPOSE: This study tests the effect of altering forward postural lean and lean strategy on running economy, kinematics, and muscle activity. METHODS: 16 healthy young adult runners (23±5 years, 8M/8F) ran on a motorized treadmill at 3.58m/s using three postural lean angles [upright, moderate lean (50% of maximal lean angle), and maximal lean] and two strategies (lean from ankle and lean from waist [trunk lean]). Metabolic energy consumption, leg kinematics, and muscle activation data were recorded for all trials. RESULTS: Regardless of lean strategy, running with an increased forward postural lean (up to 8±2 degrees) increased metabolic cost (worsened economy) by 8% (p < .001), increased hip flexion (p < .001), and increased gluteus maximus (p = .016) and biceps femoris (p = .02) muscle activation during the stance phase. This relation between running economy and postural lean angle was similar between the ankle and trunk lean strategies (p = .743). CONCLUSION: Running with a large forward postural lean reduced running economy and increased reliance on less efficient extensor leg muscles. In contrast, running with a more upright or moderate forward postural lean may be more energetically optimal, and lead to improved running performance.

Association of Premorbid Anxiety and Depression Symptoms in Concussion Recovery in Collegiate Student-Athletes.

BACKGROUND: Mental health disorders are linked to prolonged concussion symptoms. However, the association of premorbid anxiety/depression symptoms with postconcussion return-to-play timelines and total symptom burden is unclear. OBJECTIVE: To examine the association of self-reported premorbid anxiety/depression symptoms in collegiate student-athletes with (1) recovery times until asymptomatic, (2) return-to-play, and (3) postconcussion symptom burden. STUDY DESIGN: Athletes in the Concussion Assessment, Research and Education Consortium completed baseline concussion assessments (Sport Concussion Assessment Tool [SCAT3] and Brief Symptom Inventory-18 [BSI-18]). Athletes were tested postinjury at <6 hours, 24 to 48 hours, time of asymptomatic and start of return-to-play protocol, unrestricted return-to-play, and 6 months after injury. Injured athletes were categorized into 4 groups based on BSI-18 scores: (1) B-ANX, elevated anxiety symptoms only; (2) B-DEP, elevated depression symptoms only; (3) B-ANX&DEP, elevated anxiety and depression symptoms; and (4) B-NEITHER, no elevated anxiety or depression symptoms. Relationship between age, sex, BSI-18 group, SCAT3 total symptom and severity scores, and time to asymptomatic status and return-to-play was assessed with Pearson's chi-squared test and robust analysis of variance. LEVEL OF EVIDENCE: Level 3. RESULTS: Among 1329 athletes with 1352 concussions, no respondents had a self-reported premorbid diagnosis of anxiety/depression. There was no difference in time until asymptomatic or time until return-to-play between BSI-18 groups (P = 0.15 and P = 0.11, respectively). B-ANX, B-DEP, and B-ANX&DEP groups did not have higher total symptom or severity scores postinjury compared with the B-NEITHER group. CONCLUSION: Baseline anxiety/depression symptoms in collegiate student-athletes without a mental health diagnosis are not associated with longer recovery times until asymptomatic, longer time to return-to-play, or higher postconcussion total symptom and severity scores compared with athletes without baseline symptoms. CLINICAL RELEVANCE: Anxiety and depression symptoms without a clear mental health diagnosis should be considered differently from other comorbidities when discussing prolonged recovery in collegiate student-athletes.

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.

The Prevalence and Influence of New or Worsened Neck Pain After a Sport-Related Concussion in Collegiate Athletes: A Study From the CARE Consortium.

BACKGROUND: Neck pain in a concussion population is an emerging area of study that has been shown to have a negative influence on recovery. This effect has not yet been studied in collegiate athletes. HYPOTHESIS: New or worsened neck pain is common after a concussion (>30%), negatively influences recovery, and is associated with patient sex and level of contact in sport. STUDY DESIGN: Cohort study; Level of evidence, 2. METHODS: Varsity-level athletes from 29 National Collegiate Athletic Association member institutions as well as nonvarsity sport athletes at military service academies were eligible for enrollment. Participants completed a preseason baseline assessment and follow-up assessments at 6 and 24 to 48 hours after a concussion, when they were symptom-free, and when they returned to unrestricted play. Data collection occurred between January 2014 and September 2018. RESULTS: A total of 2163 injuries were studied. New or worsened neck pain was reported with 47.0% of injuries. New or worsened neck pain was associated with patient sex (higher in female athletes), an altered mental status after the injury, the mechanism of injury, and what the athlete collided with. The presence of new/worsened neck pain was associated with delayed recovery. Those with new or worsened neck pain had 11.1 days of symptoms versus 8.8 days in those without (P < .001). They were also less likely to have a resolution of self-reported symptoms in ≤7 days (P < .001). However, the mean duration of the return-to-play protocol was not significantly different for those with new or worsened neck pain (7.5 ± 7.7 days) than those without (7.4 ± 8.3 days) (P = .592). CONCLUSION: This novel study shows that neck pain was common in collegiate athletes sustaining a concussion, was influenced by many factors, and negatively affected recovery.

King-Devick Sensitivity and Specificity to Concussion in Collegiate Athletes.

CONTEXT: The King-Devick (K-D) test is used to identify oculomotor impairment after concussion. However, the diagnostic accuracy of the K-D test over time has not been evaluated. OBJECTIVES: To (1) examine the sensitivity and specificity of the K-D test at 0 to 6 hours postinjury, 24 to 48 hours postinjury, the beginning of a return-to-play (RTP) protocol (asymptomatic), unrestricted RTP, and 6 months postconcussion and (2) compare outcomes between athletes with and those without concussion across confounding factors (sex, age, sport contact level, academic year, learning disorder, attention-deficit/hyperactivity disorder, migraine history, concussion history, and test administration mode). DESIGN: Retrospective, cross-sectional design. SETTING: Multiple institutions in the Concussion Assessment, Research and Education Consortium. PATIENTS OR OTHER PARTICIPANTS: A total of 320 athletes with a concussion (162 men, 158 women; age = 19.80 ± 1.41 years) were compared with 1239 total collegiate athletes without a concussion (646 men, 593 women; age = 20.31 ± 1.18 years). MAIN OUTCOME MEASURE(S): We calculated the K-D test time difference (in seconds) by subtracting the baseline from the most recent time. Receiver operator characteristic (ROC) curve and area under the curve (AUC) analyses were used to determine the diagnostic accuracy across time points. We identified cutoff scores and corresponding specificity at both the 80% and 70% sensitivity levels. We repeated ROC with AUC analyses using confounding factors. RESULTS: The K-D test predicted positive results at the 0- to 6-hour (AUC = 0.724, P < .001), 24- to 48-hour (AUC = 0.701, P < .001), RTP (AUC = 0.640, P < .001), and 6-month postconcussion (AUC = 0.615, P < .001) tim points but not at the asymptomatic time point (AUC = 0.513, P = .497). The 0- to 6-hour and 24- to 48-hour time points yielded 80% sensitivity cutoff scores of -2.6 and -3.2 seconds (ie, faster), respectively, but 46% and 41% specificity, respectively. The K-D test had a better AUC when administered using an iPad (AUC = 0.800, 95% CI = 0.747, 0.854) compared with the spiral-bound card system (AUC = 0.646, 95% CI = 0.600, 0.692; P < .001). CONCLUSIONS: The diagnostic accuracy of the K-D test was greatest at 0 to 6 hours and 24 to 48 hours postconcussion but declined across subsequent postconcussion time points. The AUCs did not differentiate between groups across confounding factors. Our negative cutoff scores indicated that practice effects contributed to improved performance, requiring athletes to outperform their baseline scores.

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.

Optimizing VOMS for identifying acute concussion in collegiate athletes: Findings from the NCAA-DoD CARE consortium.

The Vestibular/Ocular-Motor Screening (VOMS), an important component in acute (<72 h) sport-related concussion (SRC) assessment, is increasingly used alongside the Sport Concussion Assessment Tool (SCAT) and as part of the Military Acute Concussion Evaluation 2 (MACE2). VOMS demonstrates clinically useful diagnostic accuracy for acute SRC and improves the overall utility when added to the SCAT3. However, potential overlap among VOMS's vestibular and oculomotor items suggests the possibility of a more efficient version. VOMS and SCAT3 scores were analyzed for 3,958 preseason (47.8% female) and 496 acute-SRC (37.5% female) NCAA-DoD Concussion Assessment, Research, and Education (CARE) consortium collegiate athlete evaluations. Analyses revealed very large effect sizes (d = 2.39-2.45) and high correlations (rho = 0.95-0.99) among all VOMS items except near point of convergence distance (d = 0.79, rho ≤ 0.341). Receiver operating characteristic (ROC) curve analyses showed clinically useful discriminative utility for VOMS Total (AUC = 0.85) and the VOMS Total change score, where pretest symptoms were incorporated (AUC = 0.81). A modified VOMS (mVOMS) consisting of four items (smooth pursuits, horizontal saccades, horizontal vestibulo-ocular reflex, visual motion sensitivity) yielded identical AUCs to VOMS Total. Integer cutoff analyses suggest a score of ≥4 for VOMS Total and ≥4 for mVOMS Total optimizes concussion identification. Incorporating VOMS or mVOMS into SCAT3 (AUC = 0.79) significantly improved the combined tool's acute utility for acute concussion identification by a maximum of 4% (SCAT3+VOMS AUC = 0.84, SCAT3+mVOMS AUC = 0.83). Future versions of SCAT or MACE may want to consider incorporating a more parsimonious VOMS for the purpose of identifying acute concussion.

Exploration of Race and Ethnicity, Sex, Sport-Related Concussion, Depression History, and Suicide Attempts in US Youth.

Importance: Racial, ethnic, and sex disparities for concussion incidence and suicide attempts in youth have been reported, but data on the interaction of these variables in a large national data set are lacking. Understanding how race and ethnicity interact with sex and concussion to influence suicide attempts could yield critical information on the sociocultural impact of brain injury and mental health in US youth. Objective: To examine the associations of concussion history, race and ethnicity, and sex with reported suicide attempts among adolescents. Design, Setting, and Participants: This population-based cross-sectional cohort study used data from US Youth Risk Behavior Surveillance System (YRBSS) survey respondents between 2017 and 2019. Data were analyzed from May 2021 to January 2022. Exposures: Respondents reported sport- or recreation-related concussion (yes or no), depression (yes or no), and suicide attempt (yes or no) over the previous 12 months, along with race and ethnicity (categorized as American Indian or Alaska Native, Asian, Black, Hispanic/Latino, multiracial, Native Hawaiian or other Pacific Islander, and White), and sex (male or female). Main Outcomes and Measures: Two Chi-Square Automatic Interaction Detection (CHAID) decision tree models were built. The first was suicide attempt with depression history (SA-DEP), the second was suicide attempt without depression history (SA-NO DEP). CHAID uses risk factors (eg, number of concussions, race and ethnicity, sex) to divide the study sample into a series of subgroups that are nested within each other. Risk ratios (RRs) and 95% CIs were calculated for each subgroup to provide effect estimates. Results: A total of 28 442 youths aged up to 18 years (mean [SD] age, 14.6 [3.0] years; 14 411 [50.7%] female) responded to the survey. The CHAID decision trees revealed a complex interaction between race, sex, and concussion history for attempting suicide, which differed by depression history (overall accuracy, 84.4%-97.9%). Overall, depression history was the variable most strongly associated with SA (adjusted odds ratio, 11.24; 95% CI, 10.27-12.29). Concussion was the variable most strongly associated with SA-DEP (RR, 1.31; 95% CI, 1.20-1.51; P < .001). Black, Hispanic/Latino, or multiracial race and ethnicity were associated with increased risk for SA-DEP compared with others (RR, 1.59; 95% CI, 1.38-1.84; P < .001). American Indian or Alaska Native, Black, and Hispanic/Latino race and ethnicity were associated with increased risk for SA-NO DEP (RR, 1.89; 95% CI, 1.54-2.32; P < .001) compared with the remaining population. Conclusions and Relevance: These findings suggest that clinicians should consider race, ethnicity, and sex when evaluating the role of sport- or recreation-related concussion on suicide risk among US youth.

King-Devick testing and concussion recovery time in collegiate athletes.

OBJECTIVES: To assess whether the King-Devick (KD) test is useful as a prognostic test for prolonged concussion symptoms by examining the relationship between a) change in performance on KD test from baseline to within two days post-injury and b) the absolute KD time at post-concussion testing, with an outcome of time to return to play (RTP). DESIGN: Prospective Cohort Study. METHODS: Collegiate varsity athletes in the Concussion Assessment, Research, and Education (CARE) Consortium completed baseline and post-injury King-Devick tests from 2014 to 2018. Two exposures were evaluated: 1) change in KD score from baseline to within two days post-injury and 2) absolute KD score within two days post-injury, adjusted for baseline KD. We used Cox proportional hazards models to analyze the relationships between these exposures and time to RTP post-concussion. RESULTS: A total of 309 concussion injuries were included. Median baseline KD score was 40.0 s (IQR: 35.8, 45.2). Median post-injury KD score was 45.8 s (IQR: 39.8, 57.1). Median number of days until RTP in this cohort was 11 (IQR: 8, 17). Post-injury KD score adjusted for baseline KD had a stronger association with time to RTP duration (HR: 0.99 (0.98, 1.00), p = 0.03) than the difference in KD score from baseline to post-injury (HR: 0.99 (0.99, 1.00), p = 0.07). CONCLUSIONS: Higher post-injury KD scores are associated with longer RTP. The association between KD post-concussion test and longer RTP warrants further investigation to assess the utility of the KD for prognostication in a clinical setting.

Optimizing Concussion Care Seeking: The Influence of Previous Concussion Diagnosis Status on Baseline Assessment Outcomes.

BACKGROUND: The prevalence of unreported concussions is high, and undiagnosed concussions can lead to worse postconcussion outcomes. It is not clear how those with a history of undiagnosed concussion perform on subsequent standard concussion baseline assessments. PURPOSE: To determine if previous concussion diagnosis status was associated with outcomes on the standard baseline concussion assessment battery. STUDY DESIGN: Cross-sectional study; Level of evidence, 3. METHODS: Concussion Assessment, Research, and Education (CARE) Consortium participants (N = 29,934) self-reported concussion history with diagnosis status and completed standard baseline concussion assessments, including assessments for symptoms, mental status, balance, and neurocognition. Multiple linear regression models were used to estimate mean differences and 95% CIs among concussion history groups (no concussion history [n = 23,037; 77.0%], all previous concussions diagnosed [n = 5315; 17.8%], ≥1 previous concussions undiagnosed [n = 1582; 5.3%]) at baseline for all outcomes except symptom severity and Brief Symptom Inventory-18 (BSI-18) score, in which negative binomial models were used to calculate incidence rate ratios (IRRs). All models were adjusted for sex, race, ethnicity, sport contact level, and concussion count. Mean differences with 95% CIs excluding 0.00 and at least a small effect size (≥0.20), and those IRRs with 95% CIs excluding 1.00 and at least a small association (IRR, ≥1.10) were considered significant. RESULTS: The ≥1 previous concussions undiagnosed group reported significantly greater symptom severity scores (IRR, ≥1.38) and BSI-18 (IRR, ≥1.31) scores relative to the no concussion history and all previous concussions diagnosed groups. The ≥1 previous concussions undiagnosed group performed significantly worse on 6 neurocognitive assessments while performing better on only 2 compared with the no concussion history and all previous concussions diagnosed groups. There were no between-group differences on mental status or balance assessments. CONCLUSION: An undiagnosed concussion history was associated with worse clinical indicators at future baseline assessments. Individuals reporting ≥1 previous undiagnosed concussions exhibited worse baseline clinical indicators. This may suggest that concussion-related harm may be exacerbated when injuries are not diagnosed.

High efficiency in human muscle: an anomaly and an opportunity?

Can human muscle be highly efficient in vivo? Animal muscles typically show contraction-coupling efficiencies <50% in vitro but a recent study reports that the human first dorsal interosseous (FDI) muscle of the hand has an efficiency value in vivo of 68%. We examine two key factors that could account for this apparently high efficiency value: (1) transfer of cross-bridge work into mechanical work and (2) the use of elastic energy to do external work. Our analysis supports a high contractile efficiency reflective of nearly complete transfer of muscular to mechanical work with no contribution by recycling of elastic energy to mechanical work. Our survey of reported contraction-coupling efficiency values puts the FDI value higher than typical values found in small animals in vitro but within the range of values for human muscle in vivo. These high efficiency values support recent studies that suggest lower Ca(2+) cycling costs in working contractions and a decline in cost during repeated contractions. In the end, our analysis indicates that the FDI muscle may be exceptional in having an efficiency value on the higher end of that reported for human muscle. Thus, the FDI muscle may be an exception both in contraction-coupling efficiency and in Ca(2+) cycling costs, which makes it an ideal muscle model system offering prime conditions for studying the energetics of muscle contraction in vivo.

Discriminative Validity of Vestibular Ocular Motor Screening in Identifying Concussion Among Collegiate Athletes: A National Collegiate Athletic Association-Department of Defense Concussion Assessment, Research, and Education Consortium Study.

BACKGROUND: Vestibular and ocular motor screening tools, such as the Vestibular/Ocular Motor Screening (VOMS), are recognized as important components of a multifaceted evaluation of sport-related concussion. Previous research has supported the predictive utility of the VOMS in identifying concussion, but researchers have yet to examine the predictive utility of the VOMS among collegiate athletes in the first few days after injury. PURPOSE: To determine the discriminative validity of individual VOMS item scores and an overall VOMS score for identifying collegiate athletes with an acute sport-related concussion (≤72 hours) from healthy controls matched by age, sex, and concussion history. STUDY DESIGN: Case-control study; Level of evidence, 3. METHODS: Participants (N = 570) aged 17 to 25 years were included from 8 institutions of the National Collegiate Athletic Association-Department of Defense CARE Consortium (Concussion Assessment, Research, and Education): 285 athletes who were concussed (per current consensus guidelines) and 285 healthy controls matched by age, sex, and concussion history. Participants completed the VOMS within 3 days of injury (concussion) or during preseason (ie, baseline; control). Symptoms are totaled for each VOMS item for an item score (maximum, 40) and totaled across items for an overall score (maximum, 280), and distance (centimeters) for near point of convergence (NPC) is averaged across 3 trials. Receiver operating characteristic analysis of the area under the curve (AUC) was performed on cutoff scores using Youden index (J) for each VOMS item, overall VOMS score, and NPC distance average. A logistic regression was conducted to identify which VOMS scores identified concussed status. RESULTS: A symptom score ≥1 on each VOMS item and horizontal vestibular/ocular reflex ≥2 significantly discriminated concussion from control (AUC, 0.89-0.90). NPC distance did not significantly identify concussion from control (AUC, 0.51). The VOMS overall score had the highest accuracy (AUC, 0.91) for identifying sport-related concussion from control. Among the individual items, vertical saccades ≥1 and horizontal vestibular/ocular reflex ≥2 best discriminated concussion from control. CONCLUSION: The findings indicate that individual VOMS items and overall VOMS scores are useful in identifying concussion in collegiate athletes within 3 days of injury. Clinicians can use the cutoffs from this study to help identify concussion in collegiate athletes.

Bifactor Model of the Sport Concussion Assessment Tool Symptom Checklist: Replication and Invariance Across Time in the CARE Consortium Sample.

BACKGROUND: Identifying separate dimensions of concussion symptoms may inform a precision medicine approach to treatment. It was previously reported that a bifactor model identified distinct acute postconcussion symptom dimensions. PURPOSE: To replicate previous findings of a bifactor structure of concussion symptoms in the Concussion Assessment Research and Education (CARE) Consortium sample, examine measurement invariance from pre- to postinjury, and evaluate whether factors are associated with other clinical and biomarker measures. STUDY DESIGN: Cohort study (Diagnosis); Level of evidence, 2. METHODS: Collegiate athletes were prospectively evaluated using the Sport Concussion Assessment Tool-3 (SCAT-3) during preseason (N = 31,557); 2789 were followed at <6 hours and 24 to 48 hours after concussion. Item-level SCAT-3 ratings were analyzed using exploratory and confirmatory factor analyses. Bifactor and higher-order models were compared for their fit and interpretability. Measurement invariance tested the stability of the identified factor structure across time. The association between factors and criterion measures (clinical and blood-based markers of concussion severity, symptom duration) was evaluated. RESULTS: The optimal structure for each time point was a 7-factor bifactor model: a General factor, on which all items loaded, and 6 specific factors-Vestibulo-ocular, Headache, Sensory, Fatigue, Cognitive, and Emotional. The model manifested strict invariance across the 2 postinjury time points but only configural invariance from baseline to postinjury. From <6 to 24-48 hours, some dimensions increased in severity (Sensory, Fatigue, Emotional), while others decreased (General, Headache, Vestibulo-ocular). The factors correlated with differing clinical and biomarker criterion measures and showed differing patterns of association with symptom duration at different time points. CONCLUSION: Bifactor modeling supported the predominant unidimensionality of concussion symptoms while revealing multidimensional properties, including a large dominant General factor and 6 independent factors: Headache, Vestibulo-ocular, Sensory, Cognitive, Fatigue, and Emotional. Unlike the widely used SCAT-3 symptom severity score, which declines gradually after injury, the bifactor model revealed separable symptom dimensions that have distinct trajectories in the acute postinjury period and different patterns of association with other markers of injury severity and outcome. CLINICAL RELEVANCE: The SCAT-3 total score remains a valuable, robust index of overall concussion symptom severity, and the specific factors identified may inform management strategies. Because some symptom dimensions continue to worsen in the first 24 to 48 hours after injury (ie, Sensory, Fatigue, Emotional), routine follow-up in this time frame may be valuable to ensure that symptoms are managed effectively.

Estimated age of first exposure to American football and outcome from concussion.

OBJECTIVE: To examine the association between estimated age at first exposure (eAFE) to American football and clinical measures throughout recovery following concussion. METHODS: Participants were recruited across 30 colleges and universities as part of the National Collegiate Athletic Association (NCAA)-Department of Defense Concussion Assessment, Research and Education Consortium. There were 294 NCAA American football players (age 19 ± 1 years) evaluated 24-48 hours following concussion with valid baseline data and 327 (age 19 ± 1 years) evaluated at the time they were asymptomatic with valid baseline data. Participants sustained a medically diagnosed concussion between baseline testing and postconcussion assessments. Outcome measures included the number of days until asymptomatic, Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT) composite scores, Balance Error Scoring System (BESS) total score, and Brief Symptom Inventory 18 (BSI-18) subscores. The eAFE was defined as participant's age at the time of assessment minus self-reported number of years playing football. RESULTS: In unadjusted regression models, younger eAFE was associated with lower (worse) ImPACT Visual Motor Speed (R 2 = 0.031, p = 0.012) at 24-48 hours following injury and lower (better) BSI-18 Somatization subscores (R 2 = 0.014, p = 0.038) when the athletes were asymptomatic. The effect sizes were very small. The eAFE was not associated with the number of days until asymptomatic, other ImPACT composite scores, BESS total score, or other BSI-18 subscores. CONCLUSION: Earlier eAFE to American football was not associated with longer symptom recovery, worse balance, worse cognitive performance, or greater psychological distress following concussion. In these NCAA football players, longer duration of exposure to football during childhood and adolescence appears to be unrelated to clinical recovery following concussion.

King-Devick Test Reliability in National Collegiate Athletic Association Athletes: A National Collegiate Athletic Association-Department of Defense Concussion Assessment, Research and Education Report.

CONTEXT: The King-Devick (KD) test has received considerable attention in the literature as an emerging concussion assessment. However, important test psychometric properties remain to be addressed in large-scale independent studies. OBJECTIVE: To assess (1) test-retest reliability between trials, (2) test-retest reliability between years 1 and 2, and (3) reliability of the 2 administration modes. DESIGN: Cross-sectional study. SETTING: Collegiate athletic training facilities. PATIENTS OR OTHER PARTICIPANTS: A total of 3248 intercollegiate student-athletes participated in year 1 (male = 55.3%, age = 20.2 ± 2.3 years, height = 1.78 ± 0.11 m, weight = 80.7 ± 21.0 kg) and 833 participated in both years. MAIN OUTCOME MEASURE(S): Time, in seconds, to complete the KD error free. The KD test reliability was assessed between trials and between annual tests over 2 years and stratified by test modality (spiral-bound cards [n = 566] and tablet [n = 264]). RESULTS: The KD test was reliable between trials (trial 1 = 43.2 ± 8.3 seconds, trial 2 = 40.8 ± 7.8 seconds; intraclass correlation coefficient [ICC] (2,1) = 0.888, P < .001), between years (year 1 = 40.8 ± 7.4 seconds, year 2 = 38.7 ± 7.7 seconds; ICC [2,1] = 0.827, P < .001), and for both spiral-bound cards (ICC [2,1] = 0.834, P < .001) and tablets (ICC [2,1] = 0.827, P < .001). The mean change between trials for a single test was -2.4 ± 3.8 seconds. Although most athletes improved from year 1 to year 2, 27.1% (226 of 883) of participants demonstrated worse (slower) KD times (3.2 ± 3.9 seconds) in year 2. CONCLUSIONS: The KD test was reliable between trials and years and when stratified by modality. A small improvement of 2 seconds was identified with annual retesting, likely due to a practice effect; however, 27% of athletes displayed slowed performance from year 1 to year 2. These results suggest that the KD assessment was a reliable test with modest learning effects over time and that the assessment modality did not adversely affect baseline reliability.