Migraine epidemiology in collegiate student-athletes: Findings from the Concussion Assessment, Research, and Education (CARE) Consortium.

OBJECTIVE: This cross-sectional study evaluated de-identified data from the National Collegiate Athletic Association-Department of Defense Grand Alliance from 2014 to 2020 to determine the prevalence of migraine and migraine medication and to describe differences in migraine prevalence by sex, race, and sport. BACKGROUND: Epidemiological studies can help identify underdiagnosed and undertreated populations. Understanding migraine prevalence in collegiate student-athletes is essential for positive healthcare outcomes including development of prevention and treatment plans. METHODS: From a concussion baseline assessment, participant's self-reported demographics (e.g., age, sex, sport), migraine diagnosis (i.e., yes/no), and migraine medication usage (e.g., yes/no, type) determined prevalence of migraine and medication use in collegiate student-athletes. RESULTS: Migraine was reported in 5.6% (2617/47,060; 95% confidence interval [CI] 5.4%-5.8%) of the student-athletes, with higher prevalence in females, 7.5% (1319/17,628; 95% CI 7.1%-7.9%), than males, 4.6% (1298/28,116; 95% CI 4.4%-4.9%). Medication usage was reported by 36.2% (947/2617; 95% CI 34.3%-38.0%) of individuals with migraine. Migraine reporting differed by race, with Caucasian reporting highest (5.9%; 1990/33,913; 95% CI 5.6%-6.1%) and Asian the lowest (2.7%; 55/2027; 95% CI 2.1%-3.5%). Women's sports, including golf, gymnastics, and lacrosse, and men's diving and squash had higher migraine reporting than other sports. CONCLUSION: Caucasian females reported higher rates than other groups and sport influenced rates of migraine diagnosis.

Concurrent vestibular activation and postural training recalibrate somatosensory, vestibular and gaze stabilization processes.

Postural instability is a common symptom of vestibular dysfunction that impacts a person's day-to-day activities. Vestibular rehabilitation is effective in decreasing dizziness, visual symptoms and improving postural control through several mechanisms including sensory reweighting of the vestibular, visual and somatosensory systems. As part of the sensory reweighting mechanisms, vestibular activation exercises with headshaking influence vestibular-ocular reflex (VOR). However, combining challenging vestibular and postural tasks to facilitate more effective rehabilitation outcomes is under-utilized. Understanding how and why this may work is unknown. The aim of the study was to assess sensory reweighting of postural control processing and VOR after concurrent vestibular activation and weight shift training (WST) in healthy young adults. Forty-two participants (18-35years) were randomly assigned into four groups: No training/control (CTL), a novel visual feedback WST coupled with a concurrent, rhythmic active horizontal or vertical headshake activity (HHS and VHS), or the same WST with no headshake (NHS). Training was performed for five days. All groups performed baseline- and post-assessments using the video head impulse test, sensory organization test, force platform rotations and electro-oculography. Significantly decreased horizontal eye movement variability in the HHS group compared to the other groups suggests improved gaze stabilization (p = .024). Significantly decreased horizontal VOR gain (p = .040) and somatosensory downweighting (p = .050) were found in the combined headshake groups (HHS and VHS) compared to the other two groups (NHS and CTL). The training also showed a significantly faster automatic postural response (p = .003) with improved flexibility (p = .010) in the headshake groups. The concurrent training influences oculomotor function and suggests improved gaze stabilization through vestibular recalibration due to adaptation and possibly habituation. The novel protocol could be modified into progressive functional activities that would incorporate gaze stabilization exercises. The findings may have implications for future development of vestibular rehabilitation protocols.

Flow pattern-dependent mitochondrial dynamics regulates the metabolic profile and inflammatory state of endothelial cells.

Endothelial mitochondria play a pivotal role in maintaining endothelial cell (EC) homeostasis through constantly altering their size, shape, and intracellular localization. Studies show that the disruption of the basal mitochondrial network in EC, forming excess fragmented mitochondria, implicates cardiovascular disease. However, cellular consequences underlying the morphological changes in the endothelial mitochondria under distinctively different, but physiologically occurring, flow patterns (i.e., unidirectional flow [UF] versus disturbed flow [DF]) are largely unknown. The purpose of this study was to investigate the effect of different flow patterns on mitochondrial morphology and its implications in EC phenotypes. We show that mitochondrial fragmentation is increased at DF-exposed vessel regions, where elongated mitochondria are predominant in the endothelium of UF-exposed regions. DF increased dynamin-related protein 1 (Drp1), mitochondrial reactive oxygen species (mtROS), hypoxia-inducible factor 1, glycolysis, and EC activation. Inhibition of Drp1 significantly attenuated these phenotypes. Carotid artery ligation and microfluidics experiments further validate that the significant induction of mitochondrial fragmentation was associated with EC activation in a Drp1-dependent manner. Contrarily, UF in vitro or voluntary exercise in vivo significantly decreased mitochondrial fragmentation and enhanced fatty acid uptake and OXPHOS. Our data suggest that flow patterns profoundly change mitochondrial fusion/fission events, and this change contributes to the determination of proinflammatory and metabolic states of ECs.

Premorbid Primary Headache and Vestibular and Oculomotor Baseline Assessments in Collegiate Athletes.

OBJECTIVE: The purpose of this study was to determine the effects of premorbid headache status on vestibular and oculomotor baseline tests in collegiate club athletes. DESIGN: Retrospective case-control study. SETTING: Sport Concussion Laboratory. PATIENTS OR PARTICIPANTS: Collegiate club athletes with a self-reported premorbid headache history (n = 32, 19.50 ± 1.98 years, and 31% women) and age-sex-sport-matched controls (n = 32, 19.56 ± 1.47 years, and 31% women) without a self-reported headache history were included. INTERVENTIONS: Participants were grouped based on a self-reported headache history at baseline. Controls were randomly matched to self-reported headache participants by age, sex, and sport. MAIN OUTCOME MEASURES: Vestibular/ocular motor screen (VOMS) baseline symptoms, symptom provocation, near point of convergence (NPC) distance, and King-Devick (K-D) test time were compared between groups. RESULTS: Athletes with a self-reported headache history at baseline are 3.82 times more likely to have abnormal NPC scores (P = 0.032) and 4.76 times more likely to have abnormal K-D test times (P = 0.014) than those without a headache history. There was no difference in VOMS baseline symptoms or symptom provocation between groups (P > 0.05). CONCLUSIONS: Club collegiate athletes with a headache history were more likely to screen as abnormal during a vestibular/ocular motor function assessment than athletes without a history of headaches. Healthcare professionals should screen for pre-existing headache during baseline concussion assessments before test interpretation. CLINICAL RELEVANCE: A premorbid headache history at preseason baseline assessment may influence vestibular and oculomotor function, and care should be taken when interpreting these individuals' tests.

Mechanisms of injury for concussions in collegiate soccer: an NCAA/DoD CARE consortium study.

OBJECTIVE: The purpose of this study was to describe the mechanism of injury (MOI) and examine factors associated with greater risk for specific MOIs involving concussions in collegiate soccer players. METHODS: Participants included 3,288 collegiate soccer players from 28 institutions across four competitive seasons, 2014-17. MOIs were documented for 262 soccer-related concussions during the study and placed into one of four categories: collisions, unintentional contact, aerial challenges, and others. RESULTS: 70% of the concussions occurred in DI soccer players. Collisions and unintentional contact were the MOIs that resulted in 66.5% of all concussions. DI and DIII soccer players sustained more concussions by unintentional contact versus collisions and aerial challenges when compared to their DII counterparts. Defenders were more likely than midfielders to sustain concussions by aerial challenges than collisions. As expected, the field players experienced more concussions as a result of collisions, unintentional contact, and aerial challenges when compared to goalkeepers. CONCLUSIONS: Future research should explore preventive strategies for decreasing collisions, especially during aerial challenges while heading the soccer ball, and unintentional contacts from errant balls in soccer in order to decrease concussion risk.

Differences in cervical kinesthesia between amateur athletes with and without a history of contact sport participation.

Objective: Identify cervical sensorimotor function differences between amateur athletes with and without a history of contact sport participation. A secondary aim of the study was to explore the association between neck reposition error and previously identified injury risk factors.Design: Cross-sectional.Participants: 27 amateur campus recreation sport athletes with a history of contact sport participation and 20 amateur campus recreation sport athletes with no history of contact sport.Main Outcome Measures: Baseline signs and symptoms (S/S) number and severity, Neck Disability Index, total neck reposition error, maximum reposition error, cervical range of motion, and cervical isometric strength were then compared between independent factor groups (contact vs. non-contact).Results: Amateur sport athletes with a history of contact sport exposure exhibited 25.2% more total neck reposition error and 24.6% more maximum neck reposition error than athletes with no history of contact sport participation. S/S number (r2 = .12, F(2,44) = 6.2, p = .017) and S/S severity (r2 = .14, F(2,44) = 5.6, p = .02) were significantly correlated with total neck reposition error.Conclusions: Athletes with a history of contact sport participation exhibited greater cervical spine reposition error. The degree to which these sensory position-sense deficits increase risk of injury and long-term quality of life is unknown, but should be explored in future studies.

Postural Control Deficits After Repetitive Soccer Heading.

OBJECTIVE: To determine the acute effects of repetitive soccer heading on postural control. DESIGN: Prospective study; participants were divided into 2 groups: a soccer heading group and a control group. SETTING: Biomechanics laboratory. PARTICIPANTS: One hundred sixty participants, including youth (age = 13.0 ± 0.8 years), high school (age = 17.2 ± 1.0 years), and collegiate (age = 20.2 ± 1.3 years) male and female soccer players, participated in this study. INTERVENTIONS: Participants in the soccer heading group performed 12 soccer headers (initial velocity = 11.2 m/s). Postural control testing was performed both before (PRE) and immediately after (POST) the purposeful soccer headers. Control participants performed postural control testing PRE and POST a 15-minute wait period. During postural control testing, participants were asked to stand on the MobileMat (Tekscan Inc, Boston, Massachusetts) for two 2-minute intervals with their hands on their hips and their feet together with one eyes-open and one eyes-closed trial. MAIN OUTCOME MEASURES: Using the center-of-pressure data, 95% area, sway velocity, and ApEn were calculated. Multilevel linear models were used to analyze the effects of age, sex, group, condition, and concussion history simultaneously. RESULTS: Participants in the soccer heading group had significantly higher sway velocity POST than participants in the control group after controlling for age, sex, concussion history, condition, and PRE (t = -3.002; P = 0.003; 95% confidence interval, -0.482 to -0.100). There were no significant differences from PRE to POST for 95% area, M/L ApEn, and A/P ApEn. CONCLUSIONS: Repetitive soccer heading does not affect most postural control measures, even among youth athletes. However, sway velocity increased after heading relative to control participants independent of age, sex, and concussion history.

The effect of an interval fatigue protocol on Vestibular/Ocular Motor Screening (VOMS) performance.

Objective: The purpose of this study was to examine the effect of a fatigue protocol on Vestibular/Ocular Motor Screening (VOMS) performance.Design: Within subjects, repeated measures, crossover.Methods: Fifteen healthy, physically-active participants (22.20 ± 1.424 years) completed 2 sessions under 2 conditions. A pretest VOMS, condition protocol, and a posttest VOMSwere performed. The control condition consisted of rest, while the experimental consisted of a fatigue protocol.Results: The primary outcome measures were VOMS performance scores and Near Point of Convergence (NPC) measurements. Statistically significant interaction effects for NPC, F(1,14) = 9.38, p = .008, and total VOMS score, F(1,14) = 10.96, p = .005 were observed. For NPC, posttest (9.12 ± 4.99 cm) was significantly different, t(14) = -2.60, p = .021, than pretest scores (7.12 ± 3.19 cm). For total VOMS score, posttest experimental scores (4.93 ± 5.12) were significantly different, t(14) = -3.06, p = .009, than pretest severity scores (1.73 ± 3.67).Conclusions: Significant increases were found in total VOMS and NPC scores following exertional fatigue. Exertional fatigue affects symptoms associated with vestibular, and/or ocular motor system assessments. Clinicians should use the VOMS with caution immediately following activity and allow time for recovery from acute fatigue.

NFL blood levels are moderated by subconcussive impacts in a cohort of college football players.

INTRODUCTION: Repetitive subconcussive head impacts in contact/collision sports such as in US football are believed to contribute to long-term brain changes and chronic symptoms. However, the lack of tools to measure the effects of repeated subconcussion limits our understanding of potential contributions to neuropathological alterations including cellular damage. METHODS: We examined subconcussive head impacts using an accelerometer-embedded mouthguard on changes in blood levels of neurofilament light (NFL) chain in 18 Division I college football players. Plasma levels of NFL and clinical symptoms were assessed at pre-post practices. The frequency and linear and rotational head accelerations recorded via the mouthguard were examined in relation to NFL plasma changes. RESULTS: The frequency and magnitude of head impacts associated with increased NFL levels. The greater numbers of hits and head accelerations associated with greater pre- to post-practice NFL level increases (p < 0.05). Greater pre- to post-practice increases in NFL also associated with greater pre- to post-practice increases in S100ß (p < 0.001), but not with total tau. Years of football experience and concussion history did not associate with changes in NFL. CONCLUSION: Acute changes in NFL may be a clinically useful peripheral marker in tracking acute brain damage in collegiate football players, and other contact sports.

The Effect of Target Speed and Verbal Instruction on NPC Measures in a Young, Healthy, and Active Population.

Purpose: Evaluate the effect of target speed and verbal instruction on near point of convergence (NPC) measurements in a young, healthy, and active population. Methods: NPC was measured in 20 individuals with three target speeds and two sets of verbal instruction. The target speeds used were 1 cm/s, 3 cm/s, 5 cm/s, and participant self-paced. The verbal instruction given was either to indicate when the target became "double" or "blurry". Results: Paired-samples t-tests revealed significant differences between 5 cm/s (5.44 ± 2.01) and 1 cm/s (6.72 ± 2.39, p = .003), 3 cm/s (6.10 ± 2.36, p = .030) and self-paced (6.63 ± 2.26, p = .005). A significant difference (p < .001) was also found between the "double" (6.72 ± 2.39) and "blurry" (10.82 ± 3.08) conditions. Conclusion: For young, healthy and active individuals, target speed and verbal instruction matter when measuring NPC.

Blood and cerebrospinal fluid biomarkers.

Sports-related traumatic brain injuries (TBIs) range in severity from severe to subconcussive. Although technologies exist for clinical diagnosis of more severe injuries, methods for diagnosis of milder forms of brain injury are limited. Developing objective measures to indicate pathogenic processes after a suspected mild TBI is challenging for multiple reasons. The field of biomarker discovery for diagnosing TBI continues to expand, with newly identified candidate biomarkers being reported regularly. Brain-specific biomarkers include proteins derived from neurons and glia, and are often measured to assess neural injury and repair, and to predict outcomes. Ideally, changes in biomarker levels should indicate pathologic events and answer critical questions for accurate diagnosis and prognosis. For example, does the presence or a change in the biomarker level suggest greater vulnerability for sustaining a second concussion or show that the window of increased vulnerability has passed? Likewise, do changes in biomarker levels predict postconcussion syndrome or recovery/repair? Although there are numerous promising candidates for fluid biomarkers that may diagnose mild TBI or concussion, none has reached the clinic to date. In this chapter, we will define biomarkers, discuss the importance of understanding their normal and pathologic functions, and outline some considerations for interpreting detection assay results in TBI. We will then review five proposed blood and cerebrospinal fluid biomarkers (tau, neurofilament, ubiquitin carboxyl-terminal hydrolase L1, S100ß, and glial fibrillary acidic protein) used currently to address TBI. Lastly, we will discuss a future trajectory for developing new, clinically useful fluid biomarkers.

Influences of Mental Illness, Current Psychological State, and Concussion History on Baseline Concussion Assessment Performance.

BACKGROUND: A student-athlete's mental state, including history of trait anxiety and depression, or current psychological state may affect baseline concussion assessment performance. PURPOSE: (1) To determine if mental illness (anxiety, depression, anxiety with depression) influences baseline scores, (2) to determine if psychological state correlates with baseline performance, and (3) to determine if history of concussion affects Brief Symptom Inventory-18 (BSI-18) subscores of state anxiety, depression, and somatization. STUDY DESIGN: Cross-sectional study; Level of evidence, 3. METHODS: A sample of 8652 collegiate student-athletes (54.5% males, 45.5% females) participated in the Concussion Assessment, Research and Education (CARE) Consortium. Baseline assessments included a demographic form, a symptom evaluation, Standardized Assessment of Concussion, Balance Error Scoring System, a psychological state assessment (BSI-18), and Immediate Post-concussion Assessment and Cognitive Test. Baseline scores were compared between individuals with a history of anxiety (n = 59), depression (n = 283), and anxiety with depression (n = 68) and individuals without a history of those conditions (n = 8242). Spearman's rho correlations were conducted to assess the relationship between baseline and psychological state subscores (anxiety, depression, somatization) (α = .05). Psychological state subscores were compared between individuals with a self-reported history of concussions (0, 1, 2, 3, 4+) using Kruskal-Wallis tests (α = .05). RESULTS: Student-athletes with anxiety, depression, and anxiety with depression demonstrated higher scores in number of symptoms reported (anxiety, 4.3 ± 4.2; depression, 5.2 ± 4.8; anxiety with depression, 5.4 ± 3.9; no anxiety/depression, 2.5 ± 3.4), symptom severity (anxiety, 8.1 ± 9.8; depression, 10.4 ± 12.4; anxiety with depression, 12.4 ± 10.7; no anxiety/depression, 4.1 ± 6.9), and psychological distress in state anxiety (anxiety, 3.7 ± 4.7; depression, 2.5 ± 3.6; anxiety with depression, 3.8 ± 4.2; no anxiety/depression, 0.8 ± 1.8), depression (anxiety, 2.4 ± 4.0; depression, 3.2 ± 4.5; anxiety with depression, 3.8 ± 4.8; no anxiety/depression, 0.8 ± 1.8), and somatization (anxiety, 2.3 ± 2.9; depression, 1.8 ± 2.8; anxiety with depression, 2.2 ± 2.4; no anxiety/depression, 0.9 ± 1.7). A moderate positive relationship existed between all BSI-18 subscores and total symptom number (n = 8377; anxiety: rs = 0.43, P < .001; depression: rs = 0.42, P < .001; somatization: rs = 0.45, P < .001), as well as total symptom severity (anxiety: rs = 0.43, P < .001; depression: rs = 0.41, P < .001; somatization: rs = 0.45, P < .001). Anxiety, depression, and somatization subscores were greater among student-athletes that self-reported more concussions. CONCLUSION: Clinicians should be cognizant that student-athletes with a history of trait anxiety, depression, and anxiety with depression may report higher symptom score and severity at baseline. Individuals with extensive concussion history may experience greater state anxiety, depression, and somatization.

Sex and age differences in head acceleration during purposeful soccer heading.

Differences in head-neck segment mass, purposeful heading technique, and cervical strength and stiffness may contribute to differences in head accelerations across sex and age. The purpose of this study was to compare head acceleration across sex and age (youth [12-14 years old], high school and collegiate) during purposeful soccer heading. One-hundred soccer players (42 male, 58 female, 17.1 ± 3.5 years, 168.5 ± 20.3 cm, 61.5 ± 13.7 kg) completed 12 controlled soccer headers at an initial ball velocity of 11.2 m/s. Linear and rotational accelerations were measured using a triaxial accelerometer and gyroscope and were transformed to the head centre-of-mass. A MANOVA revealed a significant multivariate main effect for sex (Pillai's Trace = .165, F(2,91) = 11.868, p < .001), but not for age (Pillai's Trace = .033, F(4,182) = 0.646, p = .630). Peak linear and rotational accelerations were higher in females (40.9 ± 13.3 g; 3279 ± 1065 rad/s2) than males (27.6 ± 8.5 g, 2219 ± 823 rad/s2). These data suggest that under controlled soccer heading conditions, females may be exposed to higher head accelerations than males.

Concussion Recovery Phase Affects Vestibular and Oculomotor Symptom Provocation.

Vestibular and oculomotor testing is emerging as a valuable assessment in sport-related concussion (SRC). However, their usefulness for tracking recovery and guiding return-to-play decisions remains unclear. Therefore the purpose of this study was to evaluate their clinical usefulness for tracking SRC recovery. Vestibular and oculomotor assessments were used to measure symptom provocation in an acute group (n=21) concussed≤10 days, prolonged symptoms group (n=10) concussed ≥16 days (median=84 days), healthy group (n=58) no concussions in >6 months. Known-groups approach was used with three groups at three time points (initial, 2-week and 6-week follow-up). Provoked symptoms for Gaze-Stabilization (GST), Rapid Eye Horizontal (REH), Optokinetic Stimulation (OKS), Smooth-Pursuit Slow (SPS) and Fast (SPF) tests, total combined symptoms scores and near point convergence (NPC) distance were significantly greater at initial assessment in both injury groups compared to controls. Injury groups improved on the King-Devick test and combined symptom provocation scores across time. The acute group improved over time on REH and SPF tests, while the prolonged symptoms group improved on OKS. A regression model (REH, OKS, GST) was 90% accurate discriminating concussed from healthy. Vestibular and ocular motor tests give valuable insight during recovery. They can prove beneficial in concussion evaluation given the modest equipment, training and time requirements. The current study demonstrates that when combined, vestibular and oculomotor clinical tests aid in the detection of deficits following a SRC. Additionally, tests such as NPC, GST, REH, SPS, SPF OKS and KD provide valuable information to clinicians throughout the recovery process and may aid in return to play decisions.

Acute Changes in Plasma Total Tau Levels Are Independent of Subconcussive Head Impacts in College Football Players.

Athletes in contact sports sustain repetitive subconcussive head impacts in a brief window, yet neurophysiological sequelae from repetitive subconcussion remain unclear. This prospective longitudinal study examined a relationship between changes in plasma Tau protein levels and subconcussive impact kinematic data in 23 Division I collegiate football players during a series of pre-season practices. Plasma measures for Tau and S100ß proteins, symptom scores, and near point of convergence were obtained at pre-season baseline and pre-/post-practices. During each practice, impact frequency and linear and rotational head accelerations were recorded via an accelerometer-embedded mouth guard. There were significant elevations in plasma Tau levels at all post-practice time-points, compared with those of pre-practice and baseline levels. However, the highest degree of elevation in plasma Tau was observed after the first practice, for which players sustained the lowest number of hits and magnitudes for these hits. Subconcussive impact exposure during practice (e.g., head impact frequency and magnitude) did not predict increased plasma Tau levels. Concussion history and years of football experience also were unrelated to changes in plasma Tau levels. Increases in plasma Tau levels were associated with increases in S100ß levels only after the first practice. There were no significant associations between changes in Tau levels, symptom scores, or near point of convergence. These data suggest that the changes in levels of circulating Tau protein were independent of subconcussive head impact exposure, pointing to the possibility that other factors may have played roles in changes in plasma Tau levels.

Head and neck size and neck strength predict linear and rotational acceleration during purposeful soccer heading.

There is increasing societal concern about the long-term effects of repeated impacts from soccer heading, but there is little information about ways to reduce head impact severity. The purpose of this study was to identify factors that contribute to head acceleration during soccer heading. One-hundred soccer players completed 12 controlled soccer headers. Peak linear (PLA) and rotational (PRA) accelerations were measured using a triaxial accelerometer and gyroscope. Head acceleration contributing factors were grouped into 3 categories: size (head mass, neck girth), strength (sternocleidomastoid, upper trapezius) and technique [kinematics (trunk, head-to-trunk range-of-motion), sternocleidomastoid and upper trapezius activity]. Multiple regression analyses indicated size variables explained 22.1% of the variance in PLA and 23.3% of the variance in PRA; strength variables explained 13.3% of the variance in PLA and 17.2% of the variance in PRA; technique variables did not significantly predict PLA or PRA. These findings suggest that head and neck size and neck strength predict PLA and PRA. Anthropometric and neck strength measurements should be considered when determining an athlete's readiness to begin soccer heading.

Sex Differences in Anthropometrics and Heading Kinematics Among Division I Soccer Athletes.

BACKGROUND: Soccer players head the ball repetitively throughout their careers; this is also a potential mechanism for a concussion. Although not all soccer headers result in a concussion, these subconcussive impacts may impart acceleration, deceleration, and rotational forces on the brain, leaving structural and functional deficits. Stronger neck musculature may reduce head-neck segment kinematics. HYPOTHESIS: The relationship between anthropometrics and soccer heading kinematics will not differ between sexes. The relationship between anthropometrics and soccer heading kinematics will not differ between ball speeds. STUDY DESIGN: Pilot, cross-sectional design. LEVEL OF EVIDENCE: Level 3. METHODS: Division I soccer athletes (5 male, 8 female) were assessed for head-neck anthropometric and neck strength measurements in 6 directions (ie, flexion, extension, right and left lateral flexions and rotations). Participants headed the ball 10 times (25 or 40 mph) while wearing an accelerometer secured to their head. Kinematic measurements (ie, linear acceleration and rotational velocity) were recorded at 2 ball speeds. RESULTS: Sex differences were observed in neck girth ( t = 5.09, P < 0.001), flexor and left lateral flexor strength ( t = 3.006, P = 0.012 and t = 4.182, P = 0.002, respectively), and rotational velocity at both speeds ( t = -2.628, P = 0.024 and t = -2.227, P = 0.048). Neck girth had negative correlations with both linear acceleration ( r = -0.599, P = 0.031) and rotational velocity at both speeds ( r = -0.551, P = 0.012 and r = -0.652, P = 0.016). Also, stronger muscle groups had lower linear accelerations at both speeds ( P < 0.05). CONCLUSION: There was a significant relationship between anthropometrics and soccer heading kinematics for sex and ball speeds. CLINICAL RELEVANCE: Neck girth and neck strength are factors that may limit head impact kinematics.

Subconcussive Impact-Dependent Increase in Plasma S100ß Levels in Collegiate Football Players.

The current study investigates whether repetitive subconcussive impacts cause changes in plasma S100ß levels, and also tests the associations between S100ß changes and frequency/magnitude of impacts sustained. This prospective study of 22 Division-I collegiate football players included baseline and pre-season practices (one helmet-only and four full-gear). Blood samples were obtained and assessed for S100ß levels at baseline and pre- to post-practices; symptom scores were assessed at each time-point. An accelerometer-embedded mouthguard was employed to measure the number of impacts (hits), peak linear acceleration (PLA), and peak rotational acceleration (PRA). Because we observed a distinct gap in impact exposure (hits, PLA, and PRA), players were clustered into lower (n = 7) or higher (n = 15) impact groups based on the sum of impact kinematics from all five practices. S100ß levels significantly changed across the study duration. Although S100ß levels remained stable from baseline to all pre-practice values, statistically significant acute increases in S100ß levels were observed in all post-practice measures compared with the respective pre-practice values (range: 133-246% in the overall sample). Greater number of hits, sum of PLA, and sum of PRA were significantly associated with greater acute increases in S100ß levels. There were significant differences in head impact kinematics between lower and higher impact groups (hits, 6 vs. 43 [Mlower - Mhigher = 35, p < 0.001]; PLA, 99.4 vs. 1148.5 g [Mlower - Mhigher = 1049.1, p < 0.001]; PRA, 7589 vs. 68,259 rad/s2 [Mlower - Mhigher = 60,670, p < 0.001]). Players in the higher impact group showed consistently greater increases in plasma S100ß levels, but not symptom scores, at each post-practice than the lower impact group. Collectively, these data suggest that although players continued to play without noticeable change in symptoms, a brain-enriched serological factor suggests an acute burden from head impacts. Assessing the effects of repetitive subconcussive head impacts on acute changes in S100ß levels may be a clinically useful blood biomarker in tracking real-time acute brain damage in collegiate football players.

Vestibular Dysfunction after Subconcussive Head Impact.

Current thinking views mild head impact (i.e., subconcussion) as an underrecognized phenomenon that has the ability to cause significant current and future detrimental neurological effects. Repeated mild impacts to the head, however, often display no observable behavioral deficits based on standard clinical tests, which may lack sensitivity. The current study investigates the effects of subconcussive impacts from soccer heading with innovative measures of vestibular function and walking stability in a pre- 0-2 h, post- 24 h post-heading repeated measures design. The heading group (n = 10) executed 10 headers with soccer balls projected at a velocity of 25 mph (11.2 m/sec) over 10 min. Subjects were evaluated 24 h before, immediately after, and 24 h after soccer heading with: the modified Balance Error Scoring System (mBESS); a walking stability task with visual feedback of trunk movement; and galvanic vestibular stimulation (GVS) while standing with eyes closed on foam. A control group (n = 10) followed the same protocol with no heading. The results showed significant decrease in trunk angle, leg angle gain, and center of mass gain relative to GVS for the heading group compared with controls. Medial-lateral trunk orientation displacement and velocity during treadmill walking increased immediately after mild head impact for the heading group compared with controls. Controls showed an improvement in mBESS scores over time, indicating a learning effect, which was not observed with the heading group. These results suggest that mild head impact leads to a transient dysfunction in vestibular processing, which deters walking stability during task performance.

Physical activity levels and quality of life relate to collagen turnover and inflammation changes after running.

The purpose of this study was to determine whether an association existed between self-reported symptom and function scores and tissue turnover or inflammatory biomarker changes after a running bout among individuals with and without an acute knee-injury history. A pre-test/post-test prospective cohort study design (Level II) of 22 participants was conducted. Eleven physically active individuals with a history of anterior cruciate ligament surgery and/or meniscus surgery within 4 years of study participation were matched to 11 healthy control participants. All participants completed self-reported outcome measures (Knee Osteoarthritis Outcomes Score and Tegner activity level) assessing knee symptoms and functional levels prior to the run. Blood samples were taken both pre- and post-30-minute run at a prescribed pace on a treadmill to determine serum biomarker concentration changes. Tegner activity levels were inversely related to type II collagen/type II collagen synthesis marker ratio biomarker changes after the run (r = -0.45, p = 0.01). Quality-of-life scores pre-exercise were inversely related to interleukin-1ß changes after the run (r = -0.50, p = 0.02). No other correlation coefficients were statistically significant (r = -0.39 to 0.36). Ultimately, individuals with lower activity and quality-of-life scores experienced greater increases in collagen turnover and inflammation after a running bout, respectively. A gradual increase in activity (e.g., frequency, duration, intensity) may be warranted in this group prior to returning to activities that involve running. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:612-617, 2017.