LOWER EXTREMITY BIOMECHANICS OF AN ANKLE 'GIVING WAY' CASE DURING THE DROP LANDlNG

The purpose of our study was to present an accidental ankle 'giving way' case of a participant with chronic ankle instability (CAI) during drop landing test and compare lower extremity biomechanics with that of the participant's normal landing trials. A 7-camera Vicon system was used to capture motions of the participant drop landing from a 30-cm high box. Ground reaction forces were collected using two force plates. Lower extremity joint angles and moments were generated. Subjective comparisons were made between the giving way trial and normal trials. For the giving way trial, the participant exhibited greater ankle inversion, internal rotation and less hip abduction angle in pre-landing phase compared to the normal trials. In addition, the ankle exhibited greater eversion moment and external rotation moment in the landing phase. Center of pressure was more lateral in the giving way trial. We suggest that a more inverted and internally rotated ankle position before landing may place ankle at a high risk of giving way and sprain for CAI individuals

Head Impact Magnitude in American High School Football

OBJECTIVES: To describe determinants of head impact magnitudes between various play aspects in high school football. METHODS: Thirty-two high school American football players wore Head Impact Telemetry System instrumented helmets to capture head impact magnitude (linear acceleration, rotational acceleration, and Head Impact Technology severity profile [HITsp]). We captured and analyzed video from 13 games (n = 3888 viewable head impacts) to determine the following play aspects: quarter, impact cause, play type, closing distance, double head impact, player's stance, player's action, direction of gaze, athletic readiness, level of anticipation, player stationary, ball possession, receiving ball, and snapping ball. We conducted random intercepts general linear mixed models to assess the differences in head impact magnitude between play aspects (α = 0.05). RESULTS: The following aspects resulted in greater head impact magnitude: impacts during the second quarter (HITsp: P = .03); contact with another player (linear, rotational, HITsp: P < .001); initial head impact when the head is struck twice (linear, rotational, HITsp: P < .001); longer closing distances, especially when combined with a 3-point stance or when being struck in the head (linear: P = .03); the 2-point stance (linear, rotational, HITsp: P < .001); and offensive linemen not snapping the ball compared with those snapping the ball (rotational: P = .02, HITsp: P = .02). CONCLUSIONS: Preventing head impacts caused by contact with another player may reduce head impact magnitude in high school football. Rule or coaching changes that reduce collisions after long closing distances, especially when combined with the 3-point stance or when a player is being struck in the head, should be considered

Safe-Play Knowledge, Aggression, and Head-Impact Biomechanics in Adolescent Ice Hockey Players

Addressing safe-play knowledge and player aggression could potentially improve ice hockey sport safety

Age at First Concussion Influences Number of Subsequent Concussions

Background: Individuals that sustain their first concussion during childhood may be at greater risk for sustaining multiple concussions throughout their lifetime, due to a longer window of vulnerability. Purpose: To estimate the association between age at first concussion with number of subsequent concussions. Methods: A total of 23,582 collegiate athletes from 26 universities and military cadets from three military academies completed a concussion history questionnaire (65% males, age: 19.9±1.4years). Participants self-reported concussions and age at time of each injury. Participants with a history of concussion (n=3,647, 15.5%) were categorized as having sustained their first concussion during childhood (<10 years old - yo) or adolescence (≥10yo & ≤18yo). Poisson regression was used to model age group (childhood, adolescence) predicting number of subsequent concussions (0, 1, 2+). A second Poisson regression was developed to determine whether age at first concussion predicted number of subsequent concussions. Results: Participants self-reporting their first concussion during childhood had an increased risk of sustaining subsequent concussions (RR=2.19, 95% CI: 1.82, 2.64) compared to participants self-reporting their first concussion during adolescence. For every one-year increase in age at first concussion, we observed a 16% reduction in the risk of subsequent concussion (RR=0.84, 95% CI:0.82,0.86). Conclusion(s): Individuals self-reporting a concussion at a young age sustained a higher number of concussions prior to the age of 18. Concussion prevention, recognition, and reporting strategies are of particular need at the youth level

Age at First Concussion Influences Number of Subsequent Concussions

Background: Individuals that sustain their first concussion during childhood may be at greater risk for sustaining multiple concussions throughout their lifetime, due to a longer window of vulnerability. Purpose: To estimate the association between age at first concussion with number of subsequent concussions. Methods: A total of 23,582 collegiate athletes from 26 universities and military cadets from three military academies completed a concussion history questionnaire (65% males, age: 19.9±1.4years). Participants self-reported concussions and age at time of each injury. Participants with a history of concussion (n=3,647, 15.5%) were categorized as having sustained their first concussion during childhood (<10 years old - yo) or adolescence (≥10yo & ≤18yo). Poisson regression was used to model age group (childhood, adolescence) predicting number of subsequent concussions (0, 1, 2+). A second Poisson regression was developed to determine whether age at first concussion predicted number of subsequent concussions. Results: Participants self-reporting their first concussion during childhood had an increased risk of sustaining subsequent concussions (RR=2.19, 95% CI: 1.82, 2.64) compared to participants self-reporting their first concussion during adolescence. For every one-year increase in age at first concussion, we observed a 16% reduction in the risk of subsequent concussion (RR=0.84, 95% CI:0.82,0.86). Conclusion(s): Individuals self-reporting a concussion at a young age sustained a higher number of concussions prior to the age of 18. Concussion prevention, recognition, and reporting strategies are of particular need at the youth level

Estimating Contact Exposure in Football Using the Head Impact Exposure Estimate

Over the past decade, there has been significant debate regarding the effect of cumulative subconcussive head impacts on short and long-term neurological impairment. This debate remains unresolved, because valid epidemiological estimates of athletes' total contact exposure are lacking. We present a measure to estimate the total hours of contact exposure in football over the majority of an athlete's lifespan. Through a structured oral interview, former football players provided information related to primary position played and participation in games and practice contacts during the pre-season, regular season, and post-season of each year of their high school, college, and professional football careers. Spring football for college was also included. We calculated contact exposure estimates for 64 former football players (n=32 college football only, n=32 professional and college football). The head impact exposure estimate (HIEE) discriminated between individuals who stopped after college football, and individuals who played professional football (p<0.001). The HIEE measure was independent of concussion history (p=0.82). Estimating total hours of contact exposure may allow for the detection of differences between individuals with variation in subconcussive impacts, regardless of concussion history. This measure is valuable for the surveillance of subconcussive impacts and their associated potential negative effects

Relationship Between the King-Devick Test and Commonly Used Concussion Tests at Baseline

Context: Comprehensive assessments are recommended to evaluate sport-related concussion (SRC). The degree to which the King-Devick (KD) test adds novel information to an SRC evaluation is unknown. Objective: To describe relationships at baseline among the KD and other SRC assessments and explore whether the KD provides unique information to a multimodal baseline concussion assessment. Design: Cross-sectional study. Setting: Five National Collegiate Athletic Association institutions participating in the Concussion Assessment, Research and Education (CARE) Consortium. Patients or other participants: National Collegiate Athletic Association student-athletes (N = 2258, age = 20 ± 1.5 years, 53.0% male, 68.9% white) in 11 men's and 13 women's sports. Main outcome measure(s): Participants completed baseline assessments on the KD and (1) the Symptom Inventory of the Sport Concussion Assessment Tool-3rd edition, (2) the Brief Symptom Inventory-18, (3) the Balance Error Scoring System, (4) the Standardized Assessment of Concussion (SAC), (5) the Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT) test battery, and (6) the Vestibular/Ocular Motor Screening tool during their first year in CARE. Correlation coefficients between the KD and the 6 other concussion assessments in isolation were determined. Assessments with ρ magnitude >0.1 were included in a multivariate linear regression analysis to evaluate their relative association with the KD. Results: Scores for SAC concentration, ImPACT visual motor speed, and ImPACT reaction time were correlated with the KD (ρ = -0.216, -0.276, and 0.164, respectively) and were thus included in the regression model, which explained 16.8% of the variance in baseline KD time (P < .001, Cohen f2 = 0.20). Better SAC concentration score (β = -.174, P < .001), ImPACT visual motor speed (β = -.205, P < .001), and ImPACT reaction time (β = .056, P = .020) were associated with faster baseline KD performance, but the effect sizes were small. Conclusions: Better performance on cognitive measures involving concentration, visual motor speed, and reaction time was weakly associated with better baseline KD performance. Symptoms, psychological distress, balance, and vestibular-oculomotor provocation were unrelated to KD performance at baseline. The findings indicate limited overlap at baseline among the CARE SRC assessments and the KD

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

Height and body-mass index trajectories of school-aged children and adolescents from 1985 to 2019 in 200 countries and territories: a pooled analysis of 2181 population-based studies with 65 million participants

Summary Background Comparable global data on health and nutrition of school-aged children and adolescents are scarce. We aimed to estimate age trajectories and time trends in mean height and mean body-mass index (BMI), which measures weight gain beyond what is expected from height gain, for school-aged children and adolescents. Methods For this pooled analysis, we used a database of cardiometabolic risk factors collated by the Non-Communicable Disease Risk Factor Collaboration. We applied a Bayesian hierarchical model to estimate trends from 1985 to 2019 in mean height and mean BMI in 1-year age groups for ages 5–19 years. The model allowed for non-linear changes over time in mean height and mean BMI and for non-linear changes with age of children and adolescents, including periods of rapid growth during adolescence. Findings We pooled data from 2181 population-based studies, with measurements of height and weight in 65 million participants in 200 countries and territories. In 2019, we estimated a difference of 20 cm or higher in mean height of 19-year-old adolescents between countries with the tallest populations (the Netherlands, Montenegro, Estonia, and Bosnia and Herzegovina for boys; and the Netherlands, Montenegro, Denmark, and Iceland for girls) and those with the shortest populations (Timor-Leste, Laos, Solomon Islands, and Papua New Guinea for boys; and Guatemala, Bangladesh, Nepal, and Timor-Leste for girls). In the same year, the difference between the highest mean BMI (in Pacific island countries, Kuwait, Bahrain, The Bahamas, Chile, the USA, and New Zealand for both boys and girls and in South Africa for girls) and lowest mean BMI (in India, Bangladesh, Timor-Leste, Ethiopia, and Chad for boys and girls; and in Japan and Romania for girls) was approximately 9–10 kg/m2. In some countries, children aged 5 years started with healthier height or BMI than the global median and, in some cases, as healthy as the best performing countries, but they became progressively less healthy compared with their comparators as they grew older by not growing as tall (eg, boys in Austria and Barbados, and girls in Belgium and Puerto Rico) or gaining too much weight for their height (eg, girls and boys in Kuwait, Bahrain, Fiji, Jamaica, and Mexico; and girls in South Africa and New Zealand). In other countries, growing children overtook the height of their comparators (eg, Latvia, Czech Republic, Morocco, and Iran) or curbed their weight gain (eg, Italy, France, and Croatia) in late childhood and adolescence. When changes in both height and BMI were considered, girls in South Korea, Vietnam, Saudi Arabia, Turkey, and some central Asian countries (eg, Armenia and Azerbaijan), and boys in central and western Europe (eg, Portugal, Denmark, Poland, and Montenegro) had the healthiest changes in anthropometric status over the past 3·5 decades because, compared with children and adolescents in other countries, they had a much larger gain in height than they did in BMI. The unhealthiest changes—gaining too little height, too much weight for their height compared with children in other countries, or both—occurred in many countries in sub-Saharan Africa, New Zealand, and the USA for boys and girls; in Malaysia and some Pacific island nations for boys; and in Mexico for girls. Interpretation The height and BMI trajectories over age and time of school-aged children and adolescents are highly variable across countries, which indicates heterogeneous nutritional quality and lifelong health advantages and risks

Heterogeneous contributions of change in population distribution of body mass index to change in obesity and underweight NCD Risk Factor Collaboration (NCD-RisC)

From 1985 to 2016, the prevalence of underweight decreased, and that of obesity and severe obesity increased, in most regions, with significant variation in the magnitude of these changes across regions. We investigated how much change in mean body mass index (BMI) explains changes in the prevalence of underweight, obesity, and severe obesity in different regions using data from 2896 population-based studies with 187 million participants. Changes in the prevalence of underweight and total obesity, and to a lesser extent severe obesity, are largely driven by shifts in the distribution of BMI, with smaller contributions from changes in the shape of the distribution. In East and Southeast Asia and sub-Saharan Africa, the underweight tail of the BMI distribution was left behind as the distribution shifted. There is a need for policies that address all forms of malnutrition by making healthy foods accessible and affordable, while restricting unhealthy foods through fiscal and regulatory restrictions