Head Impact Biomechanics Differ Between Girls and Boys Youth Ice Hockey Players

The influence of sex on head impact biomechanics is unknown for youth ice hockey. We sought to determine sex differences in head impact severity and frequency in youth ice hockey players. Male (n = 110) and female (n = 25) players (13–16 years old) were recruited from a local hockey organization. Players wore helmets instrumented with the Head Impact Telemetry System for all competitions and practices throughout the season. Seven team-seasons were captured. Random intercepts general mixed linear models determined whether linear acceleration and rotational acceleration differed by sex. Linear regression models evaluated the relationship between sex and impact frequency. All head impact biomechanics were natural log-transformed as their distributions were right-skewed. Females sustained fewer impacts per player than males (27 fewer impacts per player-season, p < 0.0001) even when analysis was limited to games only (21 fewer impacts per player-season, p < 0.0001). The linear acceleration was higher among females (1.07 g; 95% CI 1.00, 1.13; p = 0.04). There were no other meaningful sex differences in head impact severity. Female players are not permitted to body check, and this likely explains why they sustain fewer head impacts than males. However, as a result, females likely sustain a higher proportion of head impacts through illegal or unintentional head contact, and these impacts may result in more force being delivered to the head

Demographic, parental, and personal factors and youth athletes' concussion-related knowledge and beliefs

Context: Currently, significant attention is focused on improving care for patients with concussions through legislative mandates that include educational interventions. Few researchers have examined young athletes' concussion knowledge and the factors that may influence their knowledge. Objective: To use the socioecological model to examine demographic, parental, and personal factors associated with youth athletes' knowledge of concussion. Our ultimate goal is to inform the planning and implementation of youth sport concussion-related interventions. Design: Cross-sectional survey. Setting: Gymnasium and classroom. Patients or Other Participants: North Carolina and Arizona youth athletes (n ¼ 225; age ¼ 8 to 15 years) active in football, boys' or girls' soccer, boys' or girls' ice hockey, or boys' or girls' lacrosse in 2012-2013. Main Outcome Measure(s): Participants completed a validated, self-administered survey. The intention and belief measures were guided by the theory of planned behavior. Perceptions of concussion and intention to seek care were examined using descriptive statistics. Athletes' concussion knowledge was modeled using linear regressions and generalized estimating equations, with child demographic and personal factors and parental knowledge and attitudes about concussion as predictors. Results: Geography, sport, parental attitudes toward concussion, and athlete age were associated with athlete knowledge in the univariable analyses (P, .10). In the multivariable model, geographic location (North Carolina versus Arizona, mean difference [MD] ¼ 2.2, 95% confidence interval [CI] ¼ 1.1, 3.2), sport (girls' soccer versus girls' lacrosse, MD ¼ 2.2, 95% CI ¼ 0.7, 3.6), more favorable parental attitudes toward concussion (MD ¼ 1.2 for a 2-standard deviation shift; 95% CI ¼ 0.3, 2.1), and older age (.12 years, MD ¼ 1.6; 95% CI ¼ 0.5, 2.6) were associated with better knowledge about concussion. Conclusions: Geographic location, sport, parental attitudes about concussion, and athlete's age influenced athletes' concussion-related perceptions, indicating the need to address multiple levels of the socioecological model when targeting youth sport interventions. Parental interventions that translate to an improved culture of youth sport by improving youth athletes' perceptions and experiences are key areas for future work

Randomized controlled trial evaluating aerobic training and common sport-related concussion outcomes in healthy participants

Context: Aerobic exercise interventions are increasingly being prescribed for concussion rehabilitation, but whether aerobic training protocols influence clinical concussion diagnosis and management assessments is unknown. Objective: To investigate the effects of a brief aerobic exercise intervention on clinical concussion outcomes in healthy, active participants. Design: Randomized controlled clinical trial. Setting: Laboratory. Patients or Other Participants: Healthy (uninjured) participants (n ¼ 40) who exercised 3 times/week. Intervention(s): Participants were randomized into the acute concussion therapy intervention (ACTIVE) training or nontraining group. All participants completed symptom, cognitive, balance, and vision assessments during 2 test sessions approximately 14 days apart. Participants randomized to ACTIVE training completed six 30-minute exercise sessions that progressed from 60% to 80% of individualized maximal oxygen consumption (Vo2max) across test sessions, while the nontraining group received no intervention. Main Outcome Measure(s): The CNS Vital Signs standardized scores, Vestibular/Ocular Motor Screening near-point convergence distance (cm), and Graded Symptom Checklist, Balance Error Scoring System, and Standardized Assessment of Concussion total scores. Results: An interaction effect was found for total symptom score (P ¼ .01); the intervention group had improved symptom scores between sessions (session 1: 5.1 6 5.8; session 2: 1.9 6 3.6). Cognitive flexibility, executive functioning, reasoning, and total symptom score outcomes were better but composite memory, verbal memory, and near-point convergence distance scores were worse at the second session (all P values, .05). However, few changes exceeded the 80% reliable change indices calculated for this study, and effect sizes were generally small to negligible. Conclusions: A brief aerobic training protocol had few meaningful effects on clinical concussion assessment in healthy participants, suggesting that current concussion-diagnostic and -assessment tools remain clinically stable in response to aerobic exercise training. This provides normative data for future researchers, who should further evaluate the effect of ACTIVE training on clinical outcomes among concussed populations

A randomized controlled trial investigating the feasibility and adherence to an aerobic training program in healthy individuals

Context: Concussion management is moving from passive rest strategies to active interventions, including aerobic exercise therapy. Little information is available regarding the feasibility and adherence of these programs. Objectives: To determine whether an aerobic exercise training program intended for rehabilitation in people with concussion is feasible. Healthy, nonconcussed subjects were studied in this phase 1 trial. Design: Phase 1 parallel-group, randomized controlled trial in a sample of healthy (nonconcussed), recreationally active university students. Setting: Laboratory. Patients: 40 healthy university students. Methods: Participants were equally randomized to acute concussion therapy intervention (ACTIVE) training or nontraining groups. All participants completed maximal cardiopulmonary exercise tests on a stationary cycle ergometer at 2 test sessions approximately 14 days apart. During this 2-week study period, ACTIVE training participants completed six 30-minute cycling sessions, progressing from 60% to 80% of the participant's individualized maximal oxygen consumption. A subset of participants (NACTIVE = 12, Nnontraining = 11) wore physical activity monitors throughout the 2-week study period. Main Outcomes Measures: Study protocol and randomization effectiveness, exercise safety and adherence, and progressive intensity of the ACTIVE training procedures. Results: No adverse events occurred during any exercise sessions. Twelve ACTIVE training participants (60%) completed all training sessions, and every participant completed at least 4 sessions. Heart rate increased throughout the training period (P < .001), but symptom changes and training adherence remained stable despite the progressively increasing workload. ACTIVE training participants completed approximately 30 additional minutes of physical activity on training sessions days, although that was not statistically significant (P = .20). Conclusions: University-aged students were adherent to the ACTIVE training protocol. Future research should investigate the safety and feasibility of aerobic training programs in acutely concussed individuals to determine their appropriateness as a clinical rehabilitation strategy

Evaluating the "threshold Theory": Can Head Impact Indicators Help?

Purpose This study aimed to determine the clinical utility of biomechanical head impact indicators by measuring the sensitivity, specificity, positive predictive value (PV+), and negative predictive value (PV-) of multiple thresholds. Methods Head impact biomechanics (n = 283,348) from 185 football players in one Division I program were collected. A multidisciplinary clinical team independently made concussion diagnoses (n = 24). We dichotomized each impact using diagnosis (yes = 24, no = 283,324) and across a range of plausible impact indicator thresholds (10g increments beginning with a resultant linear head acceleration of 50g and ending with 120g). Results Some thresholds had adequate sensitivity, specificity, and PV-. All thresholds had low PV+, with the best recorded PV+ less than 0.4% when accounting for all head impacts sustained by our sample. Even when conservatively adjusting the frequency of diagnosed concussions by a factor of 5 to account for unreported/undiagnosed injuries, the PV+ of head impact indicators at any threshold was no greater than 1.94%. Conclusions Although specificity and PV- appear high, the low PV+ would generate many unnecessary evaluations if these indicators were the sole diagnostic criteria. The clinical diagnostic value of head impact indicators is considerably questioned by these data. Notwithstanding, valid sensor technologies continue to offer objective data that have been used to improve player safety and reduce injury risk

Association between Sensation-Seeking Behaviors and Concussion-Related Knowledge, Attitudes, Perceived Norms, and Care-Seeking Behaviors among Collegiate Student-Athletes

There are limited data connecting personality and behavioral tendencies and traits related to concussion care-seeking/disclosure behaviors and minimal research exists surrounding the relationship between risky behaviors, sensation-seeking, and concussion-related outcomes. This study examined the association between sensation-seeking and a student-athlete’s concussion-related knowledge, attitudes, perceived social norms, and concussion care-seeking/disclosure behaviors (intention to disclose concussion symptoms, perceived control over symptom disclosure, self-removal from play due to concussion symptoms, continued play with concussion symptoms, and disclosure of all concussions at the time of injury). The current study utilized a retrospective cohort of collegiate student-athletes at a single National Collegiate Athletic Association Division I institution. Separate multivariable linear regression models estimating mean differences (MD) and 95% Confidence Intervals (CI) estimated the association between sensation-seeking and concussion knowledge, concussion attitudes, and perceived social norms. Separate multivariable binomial regression models estimating adjusted prevalence ratios (PR) and 95%CI estimated the association between sensation-seeking and intention to disclose concussion symptoms, perceived control over symptom disclosure, self-removal from play due to concussion symptoms, continued play with concussion symptoms, and disclosure of all concussions at the time of injury. All models were adjusted for sex, sport participation, and concussion history. Higher sensation-seeking was significantly associated with less favorable concussion attitudes (adjusted MD = 1.93; 95%CI =-3.04,-0.83), less favorable perceived social norms surrounding concussion (adjusted MD =-1.39; 95%CI =-2.06,0.72), and continuing to play while experiencing concussion symptoms (adjusted PR = 1.50; 95%CI = 1.10, 2.06). Studentathletes with increased sensation-seeking could be at risk for failing to disclose a concussion, decreasing athlete safety and resulting in less optimal care post-injury. Results will inform future theory-based concussion education programs which consider behavioral tendencies and traits as well as sport culture to promote concussion care-seeking/disclosure and individualized interventions based on risky behavior engagement

Reaction Time and Joint Kinematics During Functional Movement in Recently Concussed Individuals

Objective: To compare movement reaction time and joint kinematics between athletes with recent concussion and matched control recreational athletes during 3 functional tasks. Design: Cross-sectional. Setting: Laboratory. Participants: College-aged recreational athletes (N=30) comprising 2 groups (15 participants each): (1) recent concussion group (median time since concussion, 126d; range, 28–432d) and (2) age- and sex-matched control group with no recent concussions. Interventions: We investigated movement reaction time and joint kinematics during 3 tasks: (1) jump landing, (2) anticipated cut, and (3) unanticipated cut. Main Outcome Measures: Reaction time and reaction time cost (jump landing reaction time–cut reaction time/jump landing reaction time×100%), along with trunk, hip, and knee joint angles in the sagittal and frontal planes at initial ground contact. Results: There were no reaction time between-group differences, but the control group displayed improved reaction time cost (10.7%) during anticipated cutting compared with the concussed group (0.8%; P=.030). The control group displayed less trunk flexion than the concussed group during the nondominant anticipated cut (5.1° difference; P=.022). There were no other kinematic between-group differences (P≥.079). Conclusions: We observed subtle reaction time and kinematic differences between individuals with recent concussion and those without concussion more than a month after return to activity after concussion. The clinical interpretation of these findings remains unclear, but may have future implications for postconcussion management and rehabilitation

Functional balance assessment in recreational college-aged individuals with a concussion history

Objectives: Despite evidence for increased musculoskeletal injury after concussion recovery, there is a lack of dynamic balance assessments that could inform management and research into this increased injury risk post-concussion. Our purpose was to identify tandem gait dynamic balance deficits in recreational athletes with a concussion history within the past 18-months compared to matched controls. Design: Cross-sectional, laboratory study. Methods: Fifteen participants with a concussion history (age: 19.7 ± 0.9 years; 9 females; median time since concussion 126 days, range 28–432 days), and 15 matched controls (19.7 ± 1.6 years; 9 females) with no recent concussion history participated. We measured center-of-pressure (COP) outcomes (velocity, path length, speed, dual-task cost) under 4 tandem gait conditions: (1) tandem gait, (2) tandem gait, eyes closed, (3) tandem gait, eyes open, cognitive distraction, and (4) tandem gait, eyes closed, cognitive distraction. Results: The concussion history group demonstrated slower tandem gait velocity compared to the control group (4.0 cm/s difference), thus velocity was used as a covariate when analyzing COP path length and speed. The concussion history group (23.5%) demonstrated greater COP speed dual-task cost than the control group (16.3%) during the eyes closed dual-task condition. No other comparisons were statistically significant. Conclusions: There may be subtle dynamic balance differences during tandem gait that are detectable after return-to-activity following concussion, but the clinical significance of these findings is unclear. Longitudinal investigations should identify acute movement deficits in varying visual and cognitive scenarios after concussion in comparison with recovery on traditional concussion assessment tools while also recording musculoskeletal injury outcomes

Association between concussion and mental health in former collegiate athletes

Background: The existing research on the association between concussion and mental health outcomes is largely limited to former professional athletes. This cross-sectional study estimated the association between recurrent concussion and depression, impulsivity, and aggression in former collegiate athletes. Methods: Former collegiate athletes who played between 1987–2012 at a Division I university completed an online questionnaire. The main exposure, total number of self-recalled concussions (sport-related and non-sport-related), were categorized as: zero (referent), one, two, or three or more concussions. The main outcomes were the depression module of The Patient Health Questionnaire (PHQ-9), the Short Form of the Barratt Impulsiveness scale (BIS15); and the 12-item Short Form of the Buss-Perry Aggression Questionnaire (BPAQ-SF). Depression was categorized into a binomial severity classification that differentiated between no or mild depression (PHQ-9 scores <10) and moderate to severe depression (PHQ-9 scores ≥10). Impulsivity and aggression were kept as continuous outcomes. Binomial regression estimated adjusted prevalence ratios (PR). Linear regression estimated adjusted mean differences (MD). Results: Of the 797 respondents with complete data (21.9% completion rate), 38.8% reported at least one concussion. Controlling for alcohol dependence and family history of depression, the prevalence of moderate to severe depression among former collegiate athletes reporting three or more concussions in total was 2.4 times that of those reporting zero concussions [95% Confidence Interval (CI): 1.0, 5.7]. Controlling for alcohol dependence, family history of anxiety, relationship status, obtaining a post-graduate degree, and playing primary college sport professionally, former collegiate athletes reporting two or more concussions in total had higher mean scores for impulsivity, compared to those reporting no concussions (2 concussions MD = 2.7; 95% CI: 1.2, 4.1; 3+ concussions MD = 1.9; 95% CI: 0.6, 3.2). Controlling for alcohol dependence, sex, and relationship status, former collegiate athletes reporting three or more concussions in total had a higher mean score for aggression, compared to those reporting no concussions (MD = 3.0; 95% CI: 1.4, 4.7). Conclusions: Our study found an association between former concussion and greater risk of severe depression and higher levels of impulsivity and aggression among former collegiate athletes. Additional prospective studies better addressing causality and ascertaining valid lifetime concussion histories and medical histories are needed

Agreement between athlete-recalled and clinically documented concussion histories in former collegiate athletes

Background: Athlete-recalled and clinically documented concussion histories have been used in research on former athletes, but both have limitations. Comparisons of these 2 types of concussion histories are needed to improve the accuracy of estimates of concussion history for future research and clinical care. Purpose: To estimate the agreement between athlete-recalled and clinically documented concussion histories during college and to explore reasons for differences. Study: Cohort study (diagnosis); Level of evidence, 3. Methods: Athlete-recalled concussion histories were provided by a convenience sample of 130 former collegiate athletes using an online questionnaire, and they were individually linked to previously collected clinical data that tracked medically diagnosed concussions at the host institution from 1996 to 2012. The intraclass correlation coefficient (ICC2,1) was used to assess agreement between athlete-recalled and clinically documented concussion histories. Descriptive analyses were performed to assess reasons for disagreement. Results: Agreement between athlete-recalled and clinically documented concussion histories was low (ICC2,1 = 0.21; 95% confidence interval, 0.05-0.37), but it was higher for women (ICC2,1 = 0.65; 95% confidence interval, 0.44-0.79) and for athletes playing more recently (2005-2012; ICC2,1 = 0.39; 95% confidence interval, 0.01-0.67). Of the 53 athletes who self-reported college sportsrelated concussions, 40% believed that they sustained impacts that should have been diagnosed as concussions but were undetected, and 21% admitted nondisclosure of suspected concussions. Common reasons for nondisclosure included the following: did not think injury was serious enough (91%), did not know it was a concussion (73%), and did not want to leave the game/practice (73%). Conclusion: Given the low agreement between athlete-recalled and clinically documented concussion histories, methodologic research is needed to improve the quality of tools used to assess concussion histories in former athletes. © 2014 The Author(s)