The overarching purposes of this research were to (a) explore an under-acknowledged and under-emphasized aspect of the sport-related concussion experience: psychosocial factors of the injury experience and (b) identify possible intervention opportunities to support the associated psychological and social needs. A collaborative inquiry (Bray et al., 2000) was employed to generate data on the psychosocial experience of concussions in elite sport and to co-develop support strategies from a sport psychology lens. This qualitative research project involved three phases during which psychological and social needs, as well as psychosocial factors that facilitated and/or hindered the concussion recovery process, were discussed through two lenses. The first lens was an experiential one, whereby elite athletes who became concussed as a result of their sport engagement shared their experiences (Phase A). The second lens was that of professional expertise, whereby mental performance consultants who work in elite sport and deliver psychosocial support to concussed elite athletes shared their perspectives and clients’ experiences (Phase B). Following the sharing of these perspectives, a community of practice (Wenger et al., 2002) of mental performance consultants was formed to collaboratively discuss how mental performance consultants might be able to support the aforementioned psychological and social needs, and ultimately, concussion recovery (Phase C). Phase A. Ten elite athletes (as defined by Swann et al., 2015) participated in semi-structured focus groups (Smith & Sparkes, 2016). Athletes discussed their experiences of injury, challenges, facilitators and barriers to recovery, support mechanisms, support that was lacking but desired, and what they would do to help someone else with a concussion. The transcripts from these focus groups (n = 5, M = 58.1 min, Range: 46-88 min), follow-up questions, and informal conversations were analyzed using thematic narrative analysis (Smith, 2016), contributing to an understanding of the athletes’ lived experiences. Phase B. Nine mental performance consultants from the Canadian Sport Psychology Association and/or Association for Applied Sport Psychology who were working in high-performance sport participated in three focus groups (M = 79 min, Range = 66-98 min). Mental performance consultants were asked about their time in the field and other aspects of their consulting experience (e.g., sports, integrated within teams or not), the types of interventions they have done with concussed athletes, their perceptions of psychosocial support during the phases of concussion management, and challenges to effective service delivery. Verbatim transcripts of these focus groups were sent to the consultants and member reflections were requested (Smith & McGannon, 2018). The generated data were thematically analyzed using a six-phase cyclical and iterative approach (Braun et al., 2016). Phase C. Eight mental performance consultants from various sport contexts formed a community of practice (Wenger et al., 2002; E. Wenger-Trayner & Wenger-Trayner, 2021). The group met over a period of four months (n = 8 meetings, M = 80 min, Range = 60-90 min). These meetings were intended to address the identified interests of the members of the community regarding support for concussed elite athletes. Concussion symptomatology, management efforts, and research were discussed; and professional scope of practice and intervention opportunities were explored through best practice discussions, client case studies, and engagements with two external experts. Mental performance consultants completed individual reflections (i.e., weekly reflective questions, value creation stories, personal value narratives; Wenger et al., 2011; E. Wenger-Trayner & Wenger-Trayner, 2015) resulting in 34 single-spaced pages of generated data, which were analyzed using the Value Creation Framework (E. Wenger-Trayner & Wenger-Trayner, 2015; 2021). The results of this multi-phase collaborative inquiry are presented in four articles. The first article offers a multi-systems perspective (Bronfenbrenner, 1977; 1979; 1992) on athletes’ concussion experiences by exploring two collaboratively created narratives (Wertz, 2011; Willis, 2019) from the engagements with athletes in Phase A. Five themes (i.e., athletic identity, (dis)trust in relationships, concussion protocols, sport culture, and timing related to major events and recovery) are discussed. The second article combines the perspectives of athletes from Phase A and mental performance consultants in Phase B to identify psychological and social needs across the concussion recovery process. Four psychological needs (i.e., acceptance, normality, confidence, self-efficacy) and two social needs (i.e., trust in relationships, social support) were identified by both populations. The third article was collaboratively written to practically present how and where mental performance consultants can support concussed athletes across the phases of the injury based on the discussions in Phase C. Scope of practice, collaboration opportunities, and intervention strategies are discussed across four phases of injury (i.e., pre-injury, injury onset, rehabilitation, return to sport). The fourth article reflects the mental performance consultants’ participatory experiences in Phase C by exploring the value of the community of practice as a professional development and knowledge translation tool. Positive value was experienced across all eight cycles of the Value Creation Framework. Through the general discussion and practical implications sections of this dissertation, these results are situated within the landscapes of concussion research and practice to highlight opportunities for transforming concussion protocols and broadening the overall lens through which the concussion experience can be examined.

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Ice hockey players are at a high risk to sustain a concussion. Most of the concussion-inducing hits are to the jaw region, nevertheless, most players do not wear any protective gear shielding the jaw.  This parametric study used finite element simulations in LS-Dyna to evaluate the potential of foam materials in a jaw guard that could be attached to a helmet to reduce the concussion risk.  Here, it was investigated how nine different foam materials influence the ability of the jawguard to protect against concussion. Furthermore, aspects like foam thickness, shell thickness, and the impacting object were evaluated. In a second part, the formerly used HIII head model was exchanged with the KTH HBM, a FE model with a detailed representation of a jaw, and it was looked at how a movable jaw affects the head kinematics. Stiffer foams with a certain stress-strain behavior tend to aid best in energy absorption in the simulated crash scenarios and therefore lower the risk of sustaining a concussion. Impact angle and location influence the result significantly. Two simulated impacts show a decrease in concussion risk by up to 8.2\% and 6.9\% respectively when the jawguard was implemented, while the two other impacts resulted in an increase in concussion risk. Shell and foam thickness variation results depend mostly on the impact scenarios. However, it was found that a soft impactor helps tremendously in avoiding concussions. The hits on the KTH HBM tend to produce higher linear and angular accelerations but no significant difference is seen in angular velocity.  In conclusion, using stiff foams in ice hockey jawguards is a promising approach to attenuate impact energy caused by a collision during an ice hockey game. However, the effect of the jawguard on the concussion risk is very sensitive to the impact location and direction.

Ice hockey is a sport with high velocities and a large number of impacts to the head. The high occurrence of concussions is being recognized, and both short and long term consequences have been found. As body checking is the main situation inducing concussions, often in the form of shoulder-to-face impacts, there is thought to be a potential to lowering the rates of concussions with equipment that covers the jaw and chin area. In this study, in-game videos from the Swedish Hockey League were analyzed regarding impact situations and impact locations. The most occurring impact situations were simulated with finite element simulation on a Hybrid-III 50th percentile head and neck model wearing a standard ice hockey helmet. Three jawguard designs were developed and tested with the model, and seven different attachments were tested on two of the designs. The results showed varying effect of the jawguard, depending on the impact situation. In impacts to the side of the chin, all three designs reduced the strains in the brain, by successfully reducing the axial rotation. In impacts to the side of the face/head and to the front of the chin, the jawguard designs produced higher strains in the brain than without any protection. The helmet in this study was attached to the head model with a chin cup, and this may have had a significant effect on the strains of the brain. Other limitations to the simulation set up indicates that the jawguards should be tested on a more realistic model to properly evaluate the jawguard.

Athletes vary in their ability to recover from concussions. Following a concussion, a pathophysiological cascade of events transpires, rendering symptoms. One such event, the indiscriminate release of the excitatory neurotransmitter glutamate, may result in hyperactivation of glutamate receptors (e.g., N-methyl-D-aspartate receptors [NMDARs]) and self-propagate a state of neurotoxicity that may be enhanced via the concomitant release of Ca2+, particularly through NMDARs containing the NR2B subunit. Genetic variation in regulatory regions of the glutamate receptor, ionotropic N-methyl-D-aspartate 2B (GRIN2B) gene, which codes for the NR2B subunit, may play a role in varied recovery among concussed athletes. Indeed, the rs1019385 promoter single nucleotide polymorphism (SNP) has been shown to alter transcription in dominant versus recessive allele carriers such that expression of the T allele results in increased upregulation of the GRIN2B gene. Therefore, the primary purpose of this study was to determine the association of this GRIN2B SNP and concussive recovery; a second GRIN2B SNP (rs890), in the 3'untranslated region, was also explored. A secondary purpose was to examine SNP associations with initial evaluation concussion severity scores. A triple-blind, between-subjects, genetic association design was utilized. The independent variable was genotype for both GRIN2B SNPs (rs1019385, rs890). The primary dependent variable, concussive recovery, was defined as the number of days from the time of injury until full return-to-play (RTP) clearance was granted by a university concussion center's physician; recovery was categorized as either normal (≤ 20 days) or prolonged (> 20 days). The secondary dependent variables were initial evaluation concussion severity scores and consisted of: (a) vestibulo-ocular reflex (VOR) result, (b) Balance Error Scoring System (BESS) sum, and (c) Immediate Postconcussion Assessment and Cognitive Testing (ImPACT) composite scores. Fifty-three, mostly White (69.7%), male (75.0%) concussed athletes (18.96 ± 6.31 years of age) participated in the study; two participants were excluded due to inconclusive genetic results. Participants were evaluated at a university concussion center per standardized concussion assessment battery, using the aforementioned severity indicators, and provided saliva samples for genotyping experiments. Follow-up visits were performed, as needed, until participants were asymptomatic and cleared for full RTP. No significant associations were demonstrated for the codominant (p = .35, p = .70), dominant (p = .39, p = 1.00) or recessive (p = .72, p = .51) genetic models for the rs1019385 and rs890 SNPs (respectively). Similarly, there were no significant differences in any initial evaluation severity scores between genotype for any genetic model. This exploratory study investigated the association between two GRIN2B SNPs and varied concussive recovery among athletes. Although no statistical and minimal clinical significance was demonstrated, future investigations should incorporate a larger sample and next-generation sequencing to investigate the 21,000 to 25,000 genes and their variations across the human genome as complex disorders (e.g., concussions) likely involve a multitude of genetic variations (and their interactions), many with small effects. Further elucidation of genetic factors involved in concussive recovery could equip clinicians with superior counseling methods and treatment options for athletes at-risk for prolonged recovery. / Kinesiology

In this prospective longitudinal investigation of Division-I collegiate football players, the acute and longer-term effects of repetitive subconcussive impacts on plasma S100β and PINCH levels and concussion-related symptom score were examined. The first aim was to investigate the acute repetitive subconcussive impact effect by comparing the biomarker levels at pre and post full-gear practice, followed by examining the relationship of head impact magnitude and frequency of on acute increases in S100β and PINCH levels and symptom score. Hypotheses for the first aim were that there would be acute increases in plasma S100β and PINCH levels, but no change would be observed in symptom score. A significant relationship between subconcussive impact kinematics and acute changes in outcome measurements would be observed only in S100β. The second aim was to examine the longer-term effect of subconcussive effects on plasma S100β and PINCH levels as well as symptom score compared to the pre-season baseline. It was hypothesized that the players who sustained high frequency and magnitude of subconcussive impact would induce chronically high levels of plasma PINCH compared to the baseline. However, chronic effect would not be found in plasma S100β and symptom score. Independent variables were time (pre vs. post-practice), days (baseline, 1st Pads-OFF, 1st Pads-ON, 2nd Pads-ON, 3rd Pads-ON, 4th Pads-ON, and post-season), and group (higher vs. lower impact group). Dependent variables were the plasma expression of S100β and PINCH and symptom scores at each time point, pre-post differences in the plasma expression of S100β and PINCH and symptom scores, and head impact kinematics (frequency, sum of peak linear and rotational acceleration). This prospective observational study of 22 Division-I collegiate football players included pre-season baseline, pre-season practices [1 helmet-only and 4 full-gear], and post-season follow-up. Acute subconcussive effects were examined using the data from the first full-gear practice. Cumulative subconcussive effects were examined across the study duration (total 12 time points per player). Blood samples and self-reported symptom scores were obtained and blood biomarkers were assessed for pre-post practices and pre-post season. Plasma S100β expression level was assessed using a sandwich-based enzyme-linked immunosorbent assay. Plasma PINCH expression level was assessed using western blot analysis. An accelerometer-embedded mouth guard was employed to measure impact kinematics including number of impacts (hits), peak linear acceleration (PLA), and peak rotational acceleration (PRA). For examining cumulative effects, based on the previously established cut-off value of 173.5 g, players who were exposed average impact magnitudes below 173.5 g per practice were categorized into lower (n = 8) or greater than 173.5 g were categorized into higher (n = 14) impact groups. Data analysis consisted of descriptive and inferential statistics. Student’s t-tests were used to assess group differences in demographic and head impact kinematic data, acute effects using pre-post practice change in concussion-related symptom scores and biomarker levels, and longer-term effects using pre-post season change in concussion-related symptom scores and biomarker levels. Pearson r correlations were used to examine potential relationship between acute increase in outcome measures and head impact kinematics data. Two-way repeated measures ANOVAs were used to identify cumulative subconcussive effects over time in concussion-related symptoms scores and biomarker levels. If necessary, one-way ANOVA as a function of group was used to identify where cumulative effect began compared to the baseline, using Dunnett’s host-hoc correction. The alpha level was set at p < 0.05. A total of 721 head impacts were recorded from the 22 players during the 5 training camp practices. There were significant differences in head impact kinematics per practice between lower and higher impact groups [number of impacts per practice, 1.3 vs. 10.0 (p < .001); linear acceleration, 36.4 vs. 285.6 g (p < .001); rotational acceleration, 2,048.4 vs. 16,497.31 rad/s2 (p < .001), respectively]. There were no changes in self-reported concussion symptoms across the study duration. While there was no change in longer-term effect between pre-season baseline and post-season follow-up in plasma S100β level, robust and acute increase was observed in post-full gear practice (0.111 + 0.01 ng/ml) compared to pre-practice S100β level, (0.048 + 0.01 ng/ml; p < .0001). The acute increase in plasma S100β was significantly and positively correlated to the number of hits (r = 0.636, p = 0.001), sum of peak linear acceleration (r = 0.570, p = .006), and sum of peak rotational acceleration (r = 0.655, p = 0.001) sustained. For plasma PINCH level, there was a 4-fold increase at post-practice compared to that of pre-practice (p = .037), indicating the acute effect of subconcussive impacts. However, the acute increase in plasma PINCH level was independent from frequency and magnitude of impacts sustained, demonstrated by no statistically significant correlations with the number of hits (r = 0.222, p = .333), sum of peak linear acceleration (r = 0.289, p = .204), and sum of peak rotational acceleration (r = 0.297, p = .191). When players were categorized into the lower and higher impact groups and assessed across the 5 training-camp practices, consistently higher levels of plasma S100β and PINCH were found only in the higher impact group at post-practice compared to the baseline. However, plasma level of S100β and PINCH at pre-practice remained stable from the baseline, suggesting the absence of chronic effect from repetitive head impacts. When season-long effects on plasma S100β and PINCH levels were examined, 10 out of 16 players showed increase in plasma PINCH level at post-season compared to the baseline (p = .039) while no significant difference in plasma S100β level. Results from the current study suggest that subconcussive head impacts do not exert self-claimed concussion-related symptoms; however, blood biomarkers detected noticeable acute changes following repetitive subconcussive impacts. Plasma level of S100β protein can be a potential diagnostic measurement to track acute brain burden, and plasma level of PINCH protein may be reflective of the longer-term cumulative brain damage from repetitive head impacts. / Kinesiology

Dysfunctions of ocular motor and binocular vision are some of the most commonly observed problems in patients with severe traumatic brain injury. Secondarily, subjective complaints of compromised vision and ocular motor functions are also sometimes reported in mild traumatic brain injuries (mTBI). Simple ocular/vision assessments such as near point of convergence (NPC), the King-Devick Test (KDT), and stereoacuity can be performed to identify and assess these deficits, but their diagnostic accuracy has yet to be thoroughly investigated. The purpose of this study was to determine if differences exist in NPC, KDT, and stereoacuity test scores between concussed and control athletes, and to determine the diagnostic accuracy of these tests. A multicenter control group design was utilized. The independent variable was group (control vs. concussed). The dependent variables were the ocular test scores from the NPC, KDT, and stereoacuity tests. Participants were recruited from several collegiate athletic programs. In total 34 healthy, non-concussed controls (21 male, 13 female) aged 19 + 1.5 years and 19 concussions (11 male, 8 female) aged 20.42 + 1.5 years participated in the study. A concussion was operationally defined as a complex pathophysiological process affecting the brain, induced by biomechanical forces, that was diagnosed by a health care professional through the use of signs and symptoms scales, balance and neurocognitive testing. Data were analyzed using descriptive and inferential statistics. T-tests and chi-squares were performed to ensure there were no significant differences between groups on specific demographic or relevant prognostic variables (sport, sex, and concussion history). T-tests were employed to identify significant differences between groups on ocular test scores. Then clinical and statistical cutoffs for all three tests were determined. Based off of these cutoffs sensitivity, specificity, and likelihood ratios were determined for each assessment. Furthermore, receiver operating characteristic (ROC) curves were calculated to help determine the diagnostic accuracy of these assessments. The alpha level was set at p < .05 and the SPSS for Windows, Version 21.0, statistical program (IBM, Inc., Armonk, NY) was used for all data analysis. Significant differences were found between groups for all three ocular assessments. NPC demonstrated a statistical cutoff of 5.5 cm, which provided a sensitivity of 79% and specificity of 76% and an AUC of 0.827. For the KDT, a statistical cutoff time of 49.5s demonstrated a sensitivity of 58% and specificity of 72% with an AUC of 0.658. Lastly, for stereoacuity a statistical cutoff point of 28.50 arc sec was found which produced a sensitivity of 65% and specificity of 54% with a maximum AUC of 0.706. All three tests demonstrated their potential to positively contribute to the diagnosis of a concussion. / Kinesiology