Sport Specialization and Sport Motivation in Middle School-Aged Athletes

CONTEXT

Sport specialization has been assumed to have psychosocial ramifications for athletes, especially autonomous motivation, which has been associated with continued sport participation. Sport dropout is common in youth athletes, yet it is unknown how sport specialization may affect this population psychosocially.

OBJECTIVE

To determine the association of sport specialization with autonomous and controlled motivation and amotivation in middle school-aged athletes.

DESIGN

Cross-sectional study.

SETTING

An anonymous online questionnaire was distributed to athletes via schools, club sports, and social media.

PATIENTS OR OTHER PARTICIPANTS

A total of 178 athletes (male = 59%; private school = 51%; grade: sixth = 20%, seventh = 32%, eighth = 48%) completed the questionnaire.

MAIN OUTCOME MEASURE(S)

The questionnaire assessed demographics, sport participation, and motivation using the Youth Behavioral Regulation in Sport Questionnaire. Sport specialization was defined using a modified 3-point scale (low, moderate, or high) and multisport versus single-sport athletes. Nonparametric tests were used to analyze the differences among the types of motivation and specialization levels and between multisport and single-sport athletes.

RESULTS

Sport specialization categories were not significantly associated with autonomous motivation, controlled motivation, or amotivation. No significant associations were present between multisport or single-sport athletes and any type of motivation. However, multisport athletes had higher scores for intrinsic motivation, a subscale of autonomous motivation, compared with single-sport athletes (single sport: median = 5.00, 25th-75th quartile = 4.50-5.00; multisport: median = 5.00, 25th-75th quartile = 5.00-5.00; P = .04).

CONCLUSIONS

Sport motivation did not differ between sport specialization groups in middle school athletes. Dropout from sport is common in this age group but is multifactorial in nature. A lack of sport motivation could be a factor for some athletes, but all specialization groups appeared to have similar outcomes. Our exploratory analysis suggests that clinicians may consider having an open dialogue with single-sport athletes, their parents or guardians, and coaches to ensure that athletes are enjoying their sport.

Secondary School Athletic Trainers' Perceptions of How Youth Sport Specialization Impacts Workload

BACKGROUND

Youth sport specialization is a growing trend in youth sports and is associated with an increased risk of injuries and burnout. However, it is unknown how sport specialization is perceived to be affecting the working environment of secondary school athletic trainers (ATs). The purpose of this paper is to describe how ATs perceive youth sport specialization impacting their workload and whether they perceive it to impact patient safety.

HYPOTHESIS

ATs will perceive that youth sport specialization impacts their workload and could impact patient safety.

STUDY DESIGN

A sequential, explanatory mixed methods design with 2 phases: (1) cross-sectional surveys and (2) individual interviews.

LEVEL OF EVIDENCE

Level 3.

METHODS

A total of 487 secondary school ATs completed the online survey (access rate, 8.4%; completion rate, 85.4%). The survey consisted of Likert questions and included sections about aspects of workload impacted by specialization, impacts on patient safety, demographics. Ten participants were selected to complete a semi-structured interview via video conference.

RESULTS

Approximately two-thirds of ATs perceive that sport specialization impacts their workload. (Somewhat, 38.6%; Quite a bit, 25.5%; A great deal, 5.5%) Attempts to reduce or modify patient activity and a patient's time for rehabilitation were the highest rated aspects of workload impacted by sport specialization. Approximately 30% ATs (29.9%) perceive that sport specialization impacts their workload to where it may influence patient safety (Somewhat, 21.6%; Quite a bit, 6.4%; A great deal, 1.9%). Three themes and subsequent subthemes were identified from the qualitative interviews: (1) current youth sport expectations, (2) conflict between school and club sports, and (3) AT job impacts.

CONCLUSION

Secondary school ATs perceive their workload to be negatively impacted by youth sport specialization and some believe it may impact patient safety.

CLINICAL RELEVANCE

Youth sport specialization is impacting youth sport stakeholders, including ATs, in a variety of ways.

Early Sport Specialization and Long-term Throwing Arm Health in College Baseball Players

BACKGROUND

Early sport specialization is associated with increased risk of overuse injuries in several sports, including baseball. However, limited evidence exists evaluating how early sport specialization affects patient-reported outcome measures as they age. The purpose of this study was to determine differences in Kerlan-Jobe Orthopedic Clinic (KJOC) Shoulder and Elbow Scores among collegiate baseball players based on the grade when a participant first reported high specialization behaviors.

HYPOTHESIS

Baseball players who were highly specialized at a younger age will have worse throwing arm health while participating in college.

STUDY DESIGN

Cross-sectional study.

LEVEL OF EVIDENCE

Level 3.

METHODS

A total of 752 college baseball players was contacted through their institution's athletic trainer. We measured baseball specialization and KJOC scores using the validated Baseball and Sport Experience survey. Data were summarized using means and SDs, medians and interquartile ranges (IQRs), and frequencies and percentages. A Kruskal-Wallis test was used to determine differences in mean KJOC scale scores based on the earliest time the participant reported high-level specialization.

RESULTS

A total of 294 baseball players completed the survey (response rate: 39.1%). Of the 294 participants, 280 completed the KJOC scale questions to generate a total KJOC score (median: 90.5; IQR: 76.6-97.2). No significant differences in KJOC total scores (P = 0.78) existed based on the grade period in which the athlete was first highly specialized.

CONCLUSION

Early baseball specialization as a youth baseball player may not impact throwing arm health in college baseball athletes.

CLINICAL RELEVANCE

Early specialization has been linked to increased risk for overuse injuries in certain sports, but may not lead to poorer throwing arm health in college baseball players. Sports medicine clinicians and researchers may use this information to educate various stakeholders about the benefits and risks associated with early sport specialization.

Motivation and Behaviors Related to Sport Specialization in College Baseball Players

CONTEXT

Early sport specialization is a growing concern among youth sports athletes, particularly in baseball. Motivation to participate in sports is an important factor in determining which sports youth athletes participate in and why.

OBJECTIVE

The purpose of this study was to qualitatively investigate youth sport participation behaviors and motivations of college baseball players.

DESIGN

Qualitative Study.

SETTING

Online Teleconference.

PATIENTS OR OTHER PARTICIPANTS

We conducted 25 semi-structured interviews with college baseball athletes who were classified as either high-level (n=8), moderate-level (n=9), or low-level specialists (n=8) prior to college.

DATA COLLECTION AND ANALYSIS

Participants completed an individual semi-structured interview to develop an understanding of the participants' youth and high school sports experiences and associated motivations to participate in those experiences. A framework analysis approach was used to analyze transcript data to identify themes among the three specialization groups.

RESULTS

From our interview analysis, six overall themes emerged among the groups: (1) Motivation, (2) Stress, (3) Quitting, (4) Barriers, (5) Facilitators of Success, and (6) Future Directions. Moderate and high-level specialists described higher levels of passion, participating in deliberate practice, higher levels of performance-related stress, and a desire to quit sports more than low-level specialists. None of the groups described parents as an overbearing external motivator to participate in sports at an early age.

CONCLUSIONS

Participants who were classified as low-, moderate-, and high-level specialists described different experiences related to their motivation, stress levels, desire to quit, barriers to participating in baseball, facilitators of success, and their overall future career goals after completing baseball. This information may be useful for parents, coaches, and health care professionals to better communicate the benefits and risks associated with sport specialization to youth athletes. Future research is needed to determine if differences in motivation levels exist in younger populations.

A mutagenesis study of autoantigen optimization for potential T1D vaccine design

A previously reported autoreactive antigen, termed the X-idiotype, isolated from a unique cell population in Type 1 diabetes (T1D) patients, was found to stimulate their CD4+ T cells. This antigen was previously determined to bind more favorably than insulin and its mimic (insulin superagonist) to HLA-DQ8, supporting its strong role in CD4+ T cell activation. In this work, we probed HLA-X-idiotype-TCR binding and designed enhanced-reactive pHLA-TCR antigens using an in silico mutagenesis approach which we functionally validated by cell proliferation assays and flow cytometry. From a combination of single, double, and swap mutations, we identified antigen-binding sites p4 and p6 as potential mutation sites for HLA binding affinity enhancement. Site p6 is revealed to favor smaller but more hydrophobic residues than the native tyrosine, such as valine (Y6V) and isoleucine (Y6I), indicating a steric mechanism in binding affinity improvement. Meanwhile, site p4 methionine mutation to hydrophobic residues isoleucine (M4I) or leucine (M4L) modestly increases HLA binding affinity. Select p6 mutations to cysteine (Y6C) or isoleucine (Y6I) exhibit favorable TCR binding affinities, while a swap p5-p6 tyrosine-valine double mutant (V5Y_Y6V) and a p6-p7 glutamine-glutamine double mutant (Y6Q_Y7Q) exhibit enhanced HLA binding affinity but weakened TCR affinity. This work holds relevance to potential T1D antigen-based vaccine design and optimization.

Impact of COVID-19 on the physical activity, quality of life and mental health of adolescent athletes: a 2-year evaluation of over 17 000 athletes

PURPOSE

To evaluate the changes in mental health, quality of life (QOL) and physical activity (PA) among adolescent athletes during the COVID-19 pandemic as organised sports resumed.

METHODS

Adolescent athletes completed surveys including demographic and sport participation information, 7-item Generalized Anxiety Disorder, 9-item Patient Health Questionnaire, Pediatric Quality of Life Inventory and the Hospital for Special Surgery Pediatric Functional Activity Brief Scale in May 2020 following COVID-19-related sport cancellations (Spring20) and after returning to sports in May 2021 (Spring21). The groups were balanced by inverse propensity score weighting and compared using analysis of variance models and ordinal regression models.

RESULTS

17 421 participants were included (Spring20=13 002; Spring21=4419; 16.2±1.2 years; 53% female). Anxiety was significantly lower (better) in Spring21 (Spring20=7.0, 95% CI 6.9 to 7.1; Spring21=4.9, 95% CI 4.8 to 5.0, p<0.001), as was the prevalence of moderate to severe anxiety (Spring20=29.4%, Spring21=17.1%, p<0.001). Depression was significantly improved in Spring21 (Spring20=7.6, 95% CI 7.5 to 7.7; Spring21=4.6, 95% CI 4.5 to 4.8, p<0.001), as was the prevalence of moderate to severe depression (Spring20=32.2%, Spring21=15.4%, p<0.001). Athletes in Spring21 reported higher QOL (Spring20=79.6, 95% CI 79.3 to 79.9; Spring21=84.7, 95% CI 84.4 to 85.0, p<0.001) and increased levels of PA (Spring20=13.8, 95% CI 13.6 to 13.9; Spring21=22.7, 95% CI 22.6 to 22.9, p<0.001).

CONCLUSION

Early COVID-19 sports restrictions were associated with worsening mental health in adolescents. In 2021, after returning to sports, athletes reported significant improvements in mental health, QOL and PA, although mental health adversities remain an important priority.

A Multiyear Assessment of the Effect of Sport Participation on the Health of Adolescent Athletes During the COVID-19 Pandemic

CONTEXT

Sport cancellations early in the COVID-19 pandemic had a significant negative effect on the health of US adolescents. The effect of restarting sports during the pandemic has not been described.

OBJECTIVE

To identify the effect of sport participation on the health of adolescents before and during the COVID-19 pandemic.

DESIGN

Cross-sectional study.

SETTING

Sample recruited via social media.

PATIENTS OR OTHER PARTICIPANTS

Wisconsin adolescent athletes.

MAIN OUTCOME MEASURE(S)

Participants provided information regarding their age, sex, and sport(s) involvement and completed the Patient Health Questionnaire-9 Item to assess depression symptoms, the Hospital for Special Surgery Pediatric Functional Activity Brief Scale to measure physical activity, and the Pediatric Quality of Life Inventory 4.0 to measure quality of life (QoL). Data were collected in spring 2021 (Spring21; n = 1906, age = 16.0 ± 1.2 years, females = 48.8%), when interscholastic sports had fully resumed, and were compared with similar cohorts of adolescent athletes at 2 time points: (1) spring 2020 (Spring20; n = 3243, age = 16.2 ± 1.2 years, females = 57.9%) when sports were cancelled and (2) 2016-2018 (PreCOVID-19) before the pandemic (n = 5231, age = 15.7 ± 1.1 years, females = 65.0%). Comparisons were conducted via analysis-of-variance models and ordinal regressions with age and sex as covariates.

RESULTS

The prevalence of moderate to severe depression was lower in Spring21 than in Spring20 but higher than in PreCOVID-19 (PreCOVID-19 = 5.3%, Spring20 = 37.8%, Spring21 = 22.8%; P < .001). Physical activity scores (mean [95% CI]) were higher in Spring21 than in Spring20 but lower than in PreCOVID-19 (PreCOVID-19 = 23.1 [22.7, 23.5], Spring20 = 13.5 [13.3, 13.7], Spring21 = 21.9 [21.6, 22.2]). Similarly, QoL scores were higher in Spring21 than in Spring20 but lower than in PreCOVID-19 (PreCOVID-19 = 92.8 [92.5, 93.1], Spring20 = 80.7 [80.3, 81.1], Spring21 = 84.3 [83.8, 84.8]).

CONCLUSIONS

Although sports have restarted, clinicians should be aware that physical activity, mental health, and QoL are still significantly affected in adolescent athletes by the ongoing pandemic.

Understanding interactions between biomolecules and two-dimensional nanomaterials using in silico microscopes

Two-dimensional (2D) nanomaterials such as graphene are increasingly used in research and industry for various biomedical applications. Extensive experimental and theoretical studies have revealed that 2D nanomaterials are promising drug delivery vehicles, yet certain materials exhibit toxicity under biological conditions. So far, it is known that 2D nanomaterials possess strong adsorption propensities for biomolecules. To mitigate potential toxicity and retain favorable physical and chemical properties of 2D nanomaterials, it is necessary to explore the underlying mechanisms of interactions between biomolecules and nanomaterials for the subsequent design of biocompatible 2D nanomaterials for nanomedicine. The purpose of this review is to integrate experimental findings with theoretical observations and facilitate the study of 2D nanomaterial interaction with biomolecules at the molecular level. We discuss the current understanding and progress of 2D nanomaterial interaction with proteins, lipid membranes, and DNA based on molecular dynamics (MD) simulation. In this review, we focus on the 2D graphene nanosheet and briefly discuss other 2D nanomaterials. With the ever-growing computing power, we can image nanoscale processes using MD simulation that are otherwise not observable in experiment. We expect that molecular characterization of the complex behavior between 2D nanomaterials and biomolecules will help fulfill the goal of designing effective 2D nanomaterials as drug delivery platforms.

The Role of Athlete Competitiveness in High School Sport Specialization in the United States

Background:

Sport specialization has been associated with increased injury and negative psychosocial effects on young athletes. With the continuing trend toward specialization, studies have begun to examine what motivates this decision (eg, building a skill, getting a scholarship). No study has directly assessed the personal characteristics underlying these stated reasons.

Purpose/Hypothesis:

This study examined the role of athlete competitiveness (enjoyment of competition and competitive contentiousness) as a characteristic associated with propensity to specialize in the United States. We hypothesized that, at the high school level, athletes would be more likely to engage in sport specialization owing to enjoyment of competition versus competitive contentiousness.

Study Design:

Cross-sectional study; Level of evidence, 3.

Methods:

We conducted an online survey of 975 high school athletes in the United States who were recruited via the Dynata research panel. Measures included a previously published sport specialization categorization (low, medium, high) and the 2 dimensions of the Revised Competitiveness Index (enjoyment of competition and competitive contentiousness). Also collected were athlete characteristics, sports played by the athletes, level of competition, and whether they planned to play sports in college. Analytical methods employed included cross-tabulations, multinomial logit, and ordinary least squares regression.

Results:

Overall, 22.4% of the athletes reported a high, 34.8% reported a medium, and 42.9% reported a small level of specialization. No differences in the distribution of sport specialization by sex or age were observed; however, athletes who definitely planned to play in college were significantly more likely to have a high level of specialization (P < .001). Enjoyment of competition was associated with greater specialization (beta = .196; P < .001), whereas competitive contentiousness was associated with lower levels of specialization (beta = −.299; P < .001). These findings were robust to all 3 different analytical methods we employed.

Conclusion:

Study findings indicated that, while athlete competitiveness is associated with sport specialization, the nature of that competitiveness determined the association. Being an argumentative contrarian may predispose athletes to lower levels of sport specialization, whereas enjoying competition may encourage higher levels of specialization.

The Psychosocial Benefits of Sport Participation During COVID-19 Are Only Partially Explained by Increased Physical Activity

The purpose of this study was to determine whether physical activity (PA) increases were responsible for the improvements in mental health and quality of life (QOL) seen among adolescents who returned to sport during the COVID-19 pandemic.Adolescent athletes were asked to complete a survey in October 2020 regarding demographic information, whether they had returned to sport participation (no [DNP], yes [PLY]), school instruction type (virtual, in-person, hybrid), anxiety, depression, QOL, and PA. Anxiety, depression, QOL and PA were compared between PLY and DNP using least squares means from linear models adjusted for age, gender, and instruction type. Mediation analysis assessed whether the relationship between sport status and anxiety, depression, and QOL was mediated by PA. 171 athletes had returned to play, while 388 had not. PLY athletes had significantly lower anxiety (3.6±0.4 v 8.2±0.6, p<0.001) and depression (4.2±0.4 v 7.3±0.6, p<0.001), and significantly higher QOL (88.1±1.0 v 80.2±1.4, p<0.001) and PA (24.0±0.5 v 16.3±0.7, p<0.001). PA explained a significant, but relatively small portion of the difference in depression (22.1%, p=0.02) and QOL (16.0%, p=0.048) between PLY and DNP athletes, but did not explain the difference in anxiety (6.6%, p=0.20). Increased PA is only responsible for a small portion of the improvements in depression and QOL among athletes who returned to sports and unrelated to improvements in anxiety. This suggests that the majority of the mental health benefits of sport participation for adolescents during the COVID-19 pandemic are independent of, and in addition to, the benefits of increased PA.

High School Sports During the COVID-19 Pandemic: The Effect of Sport Participation on the Health of Adolescents

CONTEXT

During the fall of 2020, some high schools across the United States allowed their students to participate in interscholastic sports while others cancelled or postponed their sport programs due to concerns regarding COVID-19 transmission. What effect this has had on the physical and mental health of adolescents is unknown.

OBJECTIVE

To identify the effect of playing a sport during the COVID-19 pandemic on the health of student-athletes.

DESIGN

Cross-sectional study.

SETTING

Sample recruited via email.

PATIENTS OR OTHER PARTICIPANTS

A total of 559 Wisconsin high school athletes (age = 15.7 ± 1.2 years, female = 43.6%, male = 56.4%) from 44 high schools completed an online survey in October 2020. A total of 171 (30.6%) athletes played (PLY) a fall sport, while 388 (69.4%) did not play (DNP).

MAIN OUTCOME MEASURE(S)

Demographic data included sex, grade, and sport(s) played. Assessments were the General Anxiety Disorder-7 Item for anxiety, Patient Health Questionnaire-9 Item for depression, the Hospital for Special Surgery Pediatric Functional Activity Brief Scale for physical activity, and the Pediatric Quality of Life Inventory 4.0 for quality of life. Univariable comparisons between the 2 groups were made via t tests or χ2 tests. Means for each continuous outcome measure were compared between groups using analysis-of-variance models that controlled for age, sex, teaching method (virtual, hybrid, or in person), and the percentage of students eligible for free or reduced-price lunch.

RESULTS

The PLY group participants were less likely to report moderate to severe symptoms of anxiety (PLY = 6.6%, DNP = 44.1%, P < .001) and depression (PLY = 18.2%, DNP = 40.4%, P < .001). They also demonstrated higher (better) Pediatric Functional Activity Brief Scale scores (PLY = 23.2 [95% CI = 22.0, 24.5], DNP = 16.4 [95% CI = 15.0, 17.8], P < .001) and higher (better) Pediatric Quality of Life Inventory total scores (PLY = 88.4 [95% CI = 85.9, 90.9], DNP = 79.6 [95% CI = 76.8, 82.4], P < .001).

CONCLUSIONS

Adolescents who played a sport during the COVID-19 pandemic described fewer symptoms of anxiety and depression and had better physical activity and quality-of-life scores compared with adolescent athletes who did not play a sport.

Epidemiology of overuse injuries in U.S. secondary school athletics from 2014-2015 to 2018-2019 using the National Athletic Treatment, Injury and Outcomes Network Surveillance Program

CONTEXT

With 8 million annual participants in the United States, the epidemiology of sports-related injuries in high school athletics has garnered significant interest. The most recent studies examining overuse injury rates in high school sports reported data from 2012-2013 and therefore may not reflect current overuse injury rates in high school sports.

OBJECTIVE

To 1) to determine overuse time-loss (TL) and non-time-loss (NTL) injury rates among high school student athletes using NATION-SP data collected from 2014-2015 to 2018-2019 and 2) compare overuse injury rates based on student-athlete gender defined by sport, sport, and injury location.

DESIGN

Descriptive epidemiology study.

SETTING

Online injury surveillance from 211 high schools (345 individual years of high school data).

PATIENTS OR OTHER PARTICIPANTS

Athletes participating in secondary school-sponsored boys' and girls' sports.

MAIN OUTCOME MEASURES

Boys' and girls' overuse injury data from the National Athletic Treatment, Injury and Outcomes Network Surveillance Program (NATION-SP) from the 2014-2015 to 2018-2019 school years were analyzed. Overuse injuries were identified using a combination of reported injury mechanism and diagnosis. TL injuries resulted in restriction from participation beyond the day of injury; a NTL injury did not result in restriction from participation beyond the day of injury or lost no time due to the injury. Injury counts, rates, and rate ratios (IRRs) were reported with 95% confidence intervals (CIs).

RESULTS

The overall overuse injury rate was 5.3/10,000 AEs (95%CI=5.1, 5.7), the NTL overuse injury rate was 3.4/10,000 AEs (95%CI=3.1, 3.6), and the TL overuse injury rate was 2.0/10,000 AEs (95%CI=1.8, 2.2). The overuse injury rate was greater in girls' sports compared to boys' sports (IRR=1.9; 95%CI=1.7, 2.1). The highest rates of overuse injury were reported in girls' cross-country (19.2/10,000 AEs; 95%CI=15.0, 24.2), girls' track and field (16.0/10,000 AEs; 95%CI=13.5, 18.8), and girls' field hockey (15.1/10,000 AEs; 95%CI=10.2, 21.6). Overuse injury rates were highest for the lower extremity compared to the upper extremity (IRR=5.7; 95%CI=4.9, 6.7) and for the lower extremity compared to the trunk and spine (IRR=8.9; 95%CI=7.3, 10.8).

CONCLUSIONS

Awareness of overuse injury risk as well as prevention and intervention recommendations are necessary and should be specifically targeted towards cross-country, field hockey, and track and field athletes.

Comparing High School Sport Specialization Trends Between Division I and Club Collegiate Athletes

BACKGROUND

Adolescent athletes report that sports specialization improves their ability to receive a collegiate athletics scholarship, though this is not well-understood. The purpose of this study was to examine self-reported trends in high school specialization and influences for sport participation between Division I (D-I) and college-aged club (club) athletes.

HYPOTHESIS

There would be no difference in high school sport specialization or sport participation influences between D-I and club athletes.

STUDY DESIGN

Retrospective cross-sectional study.

LEVEL OF EVIDENCE

Level 3.

METHODS

A survey included specialization classification (low, moderate, and high) for 9th to 12th grade, age that the athlete started organized sport and his or her collegiate sport, and several influential factors for participation in one's primary high school sport (1 = no influence to 5 = extremely influential). Chi-square analyses were used to compare specialization classifications between groups. Nonparametric tests were used to determine significant differences in age-related variables and influential factors between D-I and club athletes. All analysis were also conducted with boys and girls separately.

RESULTS

Participants included 266 D-I (girls, 155; 58%) and 180 club (girls, 122; 68%) athletes. Club athletes were more likely to be classified as low specialization at every grade in high school, and this difference was more pronounced between D-I and club female athletes than male athletes. The number of years an athlete was classified as highly specialized in high school was not different between D-I and club athletes. Club athletes were more influenced by playing with friends than D-I athletes and D-I athletes were more influenced by pursuing a collegiate scholarship than club athletes.

CONCLUSION

High levels of specialization in high school sport may not be necessary for playing at the collegiate level, though some level of specialization in high school might be necessary.

CLINICAL RELEVANCE

Clinicians should advocate for healthy long-term athlete development, which does not support high specialization in high school sports.

High School Sport Specialization and Injury in Collegiate Club-Sport Athletes

CONTEXT

Sport specialization during adolescence may affect future injury risk. This association has been demonstrated in some professional sport athletes.

OBJECTIVE

To determine the association between adolescent sport specialization levels in high school and injuries sustained during collegiate club sports.

DESIGN

Cross-sectional study.

SETTING

Paper and online surveys.

PATIENTS OR OTHER PARTICIPANTS

Collegiate club-sport athletes.

MAIN OUTCOME MEASURES(S)

An anonymous survey was administered from September 2019 to May 2020. The survey included sport specialization classification via a commonly used 3-point scale (low, moderate, high) for each high school year (9th-12th), high school sports participation, and collegiate club-sport injury history. The number of years (0-4) an individual was highly specialized in high school was calculated. Individuals who participated in the same sport in high school and college were compared with individuals who played a different sport in college than in high school. An injury related to sport club activities was classified as arising from a contact, noncontact, or overuse mechanism required and the individual to seek medical treatment or diagnosis. Injuries were classified into overuse and acute mechanisms for the upper extremity, lower extremity (LE), and head/neck.

RESULTS

Single-sport participation and the number of years highly specialized in high school sport were not associated with college club-sport injuries (P > .1). Individuals who played a different collegiate club sport than their high school sport were more likely to report an LE or head/neck acute injury compared with athletes who played the same collegiate and high school sport (LE = 20% versus 8%, χ2 = 7.4, P = .006; head/neck = 16% versus 3%, χ2 = 19.4, P < .001).

CONCLUSIONS

Adolescent sport specialization was not associated with reported injuries in collegiate club-sport athletes. Collegiate club-sport athletic trainers should be aware that incoming students exploring a new sport may be at risk for LE and head/neck acute injuries.

Dynamics-Based Peptide-MHC Binding Optimization by a Convolutional Variational Autoencoder: A Use-Case Model for CASTELO

An unsolved challenge in the development of antigen-specific immunotherapies is determining the optimal antigens to target. Comprehension of antigen-major histocompatibility complex (MHC) binding is paramount toward achieving this goal. Here, we apply CASTELO, a combined machine learning-molecular dynamics (ML-MD) approach, to identify per-residue antigen binding contributions and then design novel antigens of increased MHC-II binding affinity for a type 1 diabetes-implicated system. We build upon a small-molecule lead optimization algorithm by training a convolutional variational autoencoder (CVAE) on MD trajectories of 48 different systems across four antigens and four HLA serotypes. We develop several new machine learning metrics including a structure-based anchor residue classification model as well as cluster comparison scores. ML-MD predictions agree well with experimental binding results and free energy perturbation-predicted binding affinities. Moreover, ML-MD metrics are independent of traditional MD stability metrics such as contact area and root-mean-square fluctuations (RMSF), which do not reflect binding affinity data. Our work supports the role of structure-based deep learning techniques in antigen-specific immunotherapy design.

Evolution of Thyroglobulin Loop Kinetics in EpCAM

Epithelial cell-activating molecule (EpCAM) is an important cancer biomarker and therapeutic target given its elevated expression in epithelial cancers. EpCAM is a type I transmembrane protein that forms cis-dimers along the thyroglobulin type-1A-like domain (TYD) in the extracellular region. The thyroglobulin loop (TY loop) within the TYD is structurally dynamic in the monomer state of human EpCAM, binding reversibly to a TYD site. However, it is not known if this flexibility is prevalent across different species. Here, we conduct over 17 μs of all-atom molecular dynamics simulations to study EpCAM TY loop kinetics of five different species, including human, mouse, chicken, frog, and fish. We find that the TY loop remains dynamic across evolution. In addition to the TYD binding site, we discover a second binding site for the TY loop in the C-terminal domain (CTD). Calculations of the dissociation rate constants from the simulation trajectories suggest a differential binding pattern of fish EpCAM and other organisms. Whereas fish TY loop has comparable binding for both TYD and CTD sites, the TY loops of other species preferably bind the TYD site. A hybrid construct of fish EpCAM with human TY loop restores the TYD binding preference, suggesting robust effects of the TY loop sequence on its dynamic behavior. Our findings provide insights into the structural dynamics of EpCAM and its implication in physiological functions.

Toward Guided Mutagenesis: Gaussian Process Regression Predicts MHC Class II Antigen Mutant Binding

Antigen-specific immunotherapies (ASI) require successful loading and presentation of antigen peptides into the major histocompatibility complex (MHC) binding cleft. One route of ASI design is to mutate native antigens for either stronger or weaker binding interaction to MHC. Exploring all possible mutations is costly both experimentally and computationally. To reduce experimental and computational expense, here we investigate the minimal amount of prior data required to accurately predict the relative binding affinity of point mutations for peptide-MHC class II (pMHCII) binding. Using data from different residue subsets, we interpolate pMHCII mutant binding affinities by Gaussian process (GP) regression of residue volume and hydrophobicity. We apply GP regression to an experimental data set from the Immune Epitope Database, and theoretical data sets from NetMHCIIpan and Free Energy Perturbation calculations. We find that GP regression can predict binding affinities of nine neutral residues from a six-residue subset with an average R² coefficient of determination value of 0.62 ± 0.04 (±95% CI), average error of 0.09 ± 0.01 kcal/mol (±95% CI), and with an receiver operating characteristic (ROC) AUC value of 0.92 for binary classification of enhanced or diminished binding affinity. Similarly, metrics increase to an R² value of 0.69 ± 0.04, average error of 0.07 ± 0.01 kcal/mol, and an ROC AUC value of 0.94 for predicting seven neutral residues from an eight-residue subset. Our work finds that prediction is most accurate for neutral residues at anchor residue sites without register shift. This work holds relevance to predicting pMHCII binding and accelerating ASI design.

Musculoskeletal Injuries and Their Association With Previous Concussion History: A Prospective Study of High School Volleyball and Soccer Players

BACKGROUND

Sports-related concussions may have a neurobiological recovery period that exceeds the period of clinical recovery, and one consequence of an extended neurobiological recovery may be the risk of subsequent musculoskeletal injuries. Most literature citing an increased risk of musculoskeletal injury after a sports-related concussion has been reported in populations other than adolescent athletes.

PURPOSE/HYPOTHESIS

The purpose was to prospectively determine if incidence rates of musculoskeletal injury differ between adolescent athletes with and without a previous sports-related concussion, while controlling for sex, sport, and age. A secondary aim was to determine if this relationship differs between male and female athletes of the same sport. Our hypotheses were that acute-noncontact injury rates would be higher in athletes with a previous sports-related concussion when compared with athletes without a previous sports-related concussion, and that this relationship would exist only in female athletes and not male athletes.

STUDY DESIGN

Cohort study; Level of evidence, 2.

METHODS

High school soccer and volleyball players were recruited in 2 prospective cohort studies that observed 4837 athletes during their sporting season (females, 80%; soccer, 57%; mean [SD] age, 15.6 [1.1] years). At preseason, all participants self-reported demographics and previous sports-related concussion within the past 12 months. During the sport season, team athletic trainers electronically recorded athlete exposures and injury data, including injury characteristics. Injury rates per 1000 athlete exposures and injury rate ratios (IRRs) with 95% confidence intervals were calculated. All injury rates and IRRs were adjusted for sex, age, and sport.

RESULTS

The rate of acute-noncontact lower extremity injury was 87% greater (IRR, 1.87; 95% CI, 1.29-2.74) in participants with a previous sports-related concussion versus those without one. The acute-noncontact lower extremity injury rates (IRRs) for females and males with a previous sports-related concussion were 1.76 (95% CI, 1.19-2.59) and 2.83 (95% CI, 0.85-9.50), respectively. No difference was detected in acute-contact (IRR, 0.98; 95% CI, 0.56-1.73) or overuse (IRR, 1.09; 95% CI, 0.51-2.37) lower extremity injury rates by previous sports-related concussion.

CONCLUSION

Female adolescent athletes who reported a sports-related concussion within the past 12 months were more likely to sustain an acute-noncontact lower extremity injury during their high school sports season when compared with female athletes without a previous sport-related concussion.

Changes in the Health of Adolescent Athletes: A Comparison of Health Measures Collected Before and During the CoVID-19 Pandemic

CONTEXT

In the spring of 2020, schools closed to in-person teaching and sports were cancelled to control the transmission of CoVID-19. The changes that took place to the physical and mental health among young athletes during this time remain unknown, however.

OBJECTIVE

Identify changes in the health (mental health, physical activity and quality of life) of athletes that occurred during the CoVID-19 pandemic.

DESIGN

Cross-sectional study.

SETTING

Sample recruited via social media.

PATIENTS OR OTHER PARTICIPANTS

3243 Wisconsin adolescent athletes (age=16.2±1.2 yrs., female=58% female) completed an online survey in May 2020 (DuringCoVID-19). Health measures for this cohort were compared with previously reported data for Wisconsin adolescent athletes (n=5231, age=15.7±1.2, 47% female) collected in 2016-2018 (PreCoVID-19).

MAIN OUTCOME MEASURE(S)

Demographic information included: sex, grade and sports played. Health assessments included the Patient Health Questionnaire-9 Item (PHQ-9) to identify depression symptoms, the Pediatric Functional Activity Brief Scale (PFABS) for physical activity, and the Pediatric Quality of Life Inventory 4.0 (PedsQL) for health related quality of life (HRQoL). Univariable comparisons of these variables between groups were made via t-tests or chi-square tests. Means and 95% confidence intervals (CI) for each group were estimated by survey weighted ANOVA models.

RESULTS

Compared to PreCoVID-19, a larger proportion of the During-CoVID-19 participants reported rates of moderate to severe levels of depression (9.7% vs 32.9%, p<0.001). During-CoVID-19 participants reported 50% lower (worse) PFABS scores (mean:12.2 [95%CI: 11.9, 12.5] vs 24.7 [24.5, 24.9] p<0.001) and lower (worse) PedsQL total scores compared to the PreCoVID-19 participants (78.4 [78.0, 78.8] vs. 90.9 [90.5, 91.3] p<0.001).

CONCLUSIONS

During the CoVID-19 pandemic, adolescent athletes reported increased symptoms of depression, decreased physical activity and decreased quality of life compared to adolescent athletes in previous years.

Consensus Definition of Sport Specialization in Youth Athletes Using a Delphi Approach

CONTEXT

A single, widely accepted definition of sport specialization does not exist. A consensus definition is necessary to guide youth sport stakeholders on issues associated with sport specialization.

OBJECTIVE

The aim of this study was to develop a consensus definition of youth sport specialization and to identify elements that support the construct of specialization.

DESIGN

Delphi Study Setting: Directed Surveys Patients or Other Participants: A consensus panel of 17 experts was created to provide a broad multidisciplinary perspective on sport specialization in youth athletes.

DATA COLLECTION AND ANALYSIS

The final definition was developed per an iterative process that involved four rounds of review. A comprehensive review of literature and expert input supported our initial proposed umbrella definition that included six additional elements. The study team reviewed the results after each round and changes were made to the definition based on panel feedback.

MAIN OUTCOME MEASURE(S)

Panel members were provided with the definition and six elements and then asked to rate each specific to importance, relevance, and clarity using a 4-point Likert scale.

RESULTS

In four Delphi consensus rounds, 17 experts reviewed the umbrella definition and six elements before consensus was reached. The umbrella definition and three of the initial six elements achieved >80% agreement for importance, relevance, and clarity after the fourth round of review. The remaining 3 components did not reach >80% agreement even after iterative edits and were removed. The process resulted in a final consensus definition: Sport specialization is intentional and focused participation in a single sport for a majority of the year that restricts opportunities for engagement in other sports and activities.

CONCLUSIONS

A consensus-based conceptual definition for sport specialization has been developed using a Delphi method. This definition has important implications for clinicians and sports medicine professionals who support youth athletes.

Impact of in-season injury on quality of life and sleep duration in female youth volleyball athletes: a prospective study of 2073 players

OBJECTIVES

The psychological impacts of injuries in youth athletes remain poorly defined. The purpose of this study was to evaluate the influence of injury on quality of life (QOL) and sleep in female high school volleyball athletes.

METHODS

2073 female high school volleyball players (15.6±1.1 years) completed the Pediatric Quality of Life survey (total QOL, physical, social, school, emotional and psychosocial function) and reported average sleep duration at the start and end of the season. Injury data were collected by school athletic trainers. Mixed effects linear regression models were used to compare changes in QOL and sleep duration during the season between (1) injured and uninjured athletes and (2) injured athletes who did or did not suffer a season-ending injury.

RESULTS

Time-loss injuries were reported in 187 athletes with complete preseason and postseason data. During the season, injured athletes demonstrated a greater decrease in total QOL (β=-1.3±0.5, p=0.012), as well as physical function (β=-1.6±0.6, p=0.012), school function (β=-2.0±0.76, p=0.01) and psychosocial function domains (β=-1.2±0.6, p=0.039) compared with uninjured athletes. Athletes who sustained a season-ending injury had a significantly greater decrease in total QOL (β=-6.8±2.0, p=0.006) and physical function (β=-17±2.9, p<0.001) compared with injured athletes who were able to return to play during the season.

CONCLUSION

In-season injuries are associated with significant decreases in total QOL as well as physical and psychosocial function. Healthcare providers should consider the impacts of injuries on QOL and sleep in youth athletes in order to optimise management and improve overall health.

Association of lower extremity injuries and injury mechanism with previous concussion history in adolescent athletes

OBJECTIVE

Determine the association between concussion and subsequent contact, non-contact, and overuse lower extremity (LE) injuries in a cohort of adolescent athletes. Secondarily, to identify this association between males and females.

STUDY DESIGN

Cross-sectional.

SETTING

Summer athletic events with participants ages 12-18.

MAIN OUTCOME

Anonymous survey included sport-related injuries (injury month/year) and participants classified injuries as a contact, non-contact, overuse injury, or concussion. Multivariable logistic regression analyses were used to examine associations between a concussion event and a subsequent LE injury while controlling for age and any previous LE injury.

RESULTS

A concussion was reported in 219 athletes (Female = 96, 44%) and were matched with 219 non-concussed athletes (438 total participants). Concussion was not association with a specific injury mechanism but was significant for any subsequent LE injury (OR = 1.58 95%CI = [1.03-2.41]; p < 0.05). Concussed females were more likely to report any subsequent LE injury compared to non-concussed female athletes (2.49[1.31, 4.74]; p < 0.01). This relationship was not observed between concussed and non-concussed males (1.11[0.62-1.99]; p > 0.5).

CONCLUSION

A history of concussion was associated with any subsequent LE injury, but not associated with a specific mechanism of injury. The association with concussion and a subsequent LE injury was different between males and females.

Mental Health, Physical Activity, and Quality of Life of US Adolescent Athletes During COVID-19-Related School Closures and Sport Cancellations: A Study of 13 000 Athletes

CONTEXT

In the spring of 2020, US schools closed to in-person teaching and sports were cancelled to control the transmission of coronavirus disease 2019 (COVID-19). It is critical to understand the mental and physical health of adolescent athletes during this time.

OBJECTIVE

To describe the health of athletes during COVID-19-related school closures and sport cancellations.

DESIGN

Cross-sectional study.

SETTING

A national sample recruited via social media.

PATIENTS OR OTHER PARTICIPANTS

A total of 13 002 US adolescent athletes (age = 16.3 ± 1.2 years, females = 52.9%, males = 47.0%) completed an anonymous online survey.

MAIN OUTCOME MEASURE(S)

Demographic information collected was sex, grade, sport(s) played, and zip code. Assessments used were the General Anxiety Disorder 7-Item for anxiety, Patient Health Questionnaire 9-Item for depression, the Pediatric Functional Activity Brief Scale for physical activity, and the Pediatric Quality of Life Inventory 4.0 for quality of life. Mental health, physical activity, and health-related quality-of-life variables were compared among sex, grade, sport(s) played, and poverty level using means and 95% confidence intervals (CIs) from the survey-weighted analysis of variance.

RESULTS

Females reported a higher prevalence of moderate to severe anxiety symptoms (females = 43.7% versus males = 28.2%). The Pediatric Functional Activity Brief Scale score was highest (best) for grade 9 (mean = 14.5, 95% CI = 14.0, 15.0) and lowest for grade 11 (mean = 10.9, 95% CI = 10.5, 11.3). The prevalence of depression symptoms was highest in team sport (74.1%) and lowest in individual sport (64.9%) participants. The total Pediatric Quality of Life Inventory score was lowest (worst) for athletes from counties with the highest poverty levels (high: mean = 74.5, 95% CI = 73.7, 75.3; middle: mean = 78.9, 95% CI = 78.0, 79.8; and low: mean = 78.3, 95% CI = 77.4, 79.1).

CONCLUSIONS

The health of US adolescents during the COVID-19-related school closures and sport cancellations varied to differing degrees depending on sex, grade level, type of sport participation, and level of poverty. Health policy experts should consider these findings in the future when creating and implementing policies to improve the health of adolescents in the United States.

Awareness of Concussion-Education Requirements, and -Management Plans and Concussion Knowledge in High School and Club Sport Coaches

Context

A growing number of high-school–aged athletes participate on club sport teams. Some, but not all, state concussion laws apply to both interscholastic and private sport organizations. However, concussion education, management plans, and knowledge have not been examined in club coaches who coach high school-aged athletes.

Objective

To determine if differences in concussion education, management plans, and knowledge exist between high school coaches and coaches of club sport teams.

Design

Cross-sectional study.

Setting

Online survey.

Patients or Other Participants

A total of 769 coaches (497 high school coaches, 272 club coaches coaching high school-aged athletes; 266 women [34.6%], 503 men [65.4%]) completed an anonymous online questionnaire.

Main Outcome Measure(s)

The questionnaire consisted of demographic and team information, requirements for concussion-education and -management plans, and concussion knowledge.

Results

High school coaches were more likely than club coaches to report that their organizing bodies or leagues required them to receive concussion-education information (97.4% versus 80.4%; P &lt; .001) and that their organizing bodies or leagues had a concussion-management plan (94.0% versus 70.2%; P &lt; .001). High school coaches were more likely than club coaches to correctly agree that most concussions resolve in 7 to 10 days (48.6% versus 40.1%; P = .02) and disagree that loss of consciousness is required to diagnose a concussion (87.1% versus 80.9%; P = .02).

Conclusions

Club coaches were less likely to be aware of requirements for concussion-education and -management plans from their parent organizations and scored lower on specific concussion-knowledge questions than high school coaches despite the same education requirements across groups under their state concussion laws. These results raise concerns regarding the proper management of concussions in club sports and suggest a need for greater oversight and enforcement of state laws in the club sport setting.

Training Load and Injury Among Middle School-Aged Athletes

CONTEXT

Young athletes are encouraged to participate in high-intensity sport programs. However, most research on the association between training volume (TV) and injury has been performed on adult or professional athletes.

OBJECTIVE

To evaluate the association between acute and chronic TV (hours/week) and reported injury (yes/no) and evaluate the relationship between acute : chronic TV and injury while controlling for sex, age, and prior injury in young athletes.

DESIGN

Cohort study.

SETTING

Online surveys.

PATIENTS OR OTHER PARTICIPANTS

Middle school-aged adolescents.

MAIN OUTCOME MEASURE(S)

We conducted a baseline survey at the start of the 2017-2018 academic year. The baseline survey solicited information regarding demographics, injury history, and primary sport. Subsequent surveys were delivered electronically at the start of each week. Information obtained with the weekly survey included weekly TV and injuries sustained the previous week. Injuries were reported and classified (eg, acute or gradual onset) by the participants. Weekly TV was aggregated as rolling averages over the prior 2, 3, and 4 weeks. Acute:chronic TV was calculated for each participant for every week as the prior week TV divided by the TV during the prior 2 (1 : 2), 3 (1 : 3), and 4 (1 : 4) weeks of the study period.

RESULTS

A total of 244 recruits participated. Higher average TV over the prior 4 weeks (odds ratio [OR] = 0.97; 95% confidence interval [CI] = 0.93, 1.00; P = .05) was associated with fewer reported injuries. Additionally, higher average TV over the prior 2 (OR = 0.96; 95% CI = 0.93, 0.99; P = .04), 3 (OR = 0.95; 95% CI = 0.91, 0.99; P = .02), and 4 (OR = 0.95; 95% CI = 0.91, 0.99; P = .05) weeks was associated with fewer reported acute injuries the following week. Acute:chronic TV and any injury type were not related.

CONCLUSIONS

Consistent, higher levels of physical activity may offer protection against acute injury in young athletes.

Assessment of Free-Living Cadence Using ActiGraph Accelerometers Between Individuals With and Without Anterior Cruciate Ligament Reconstruction

CONTEXT

Anterior cruciate ligament reconstruction (ACLR) and gait speed are risk factors for developing knee osteoarthritis (OA). Measuring minute-level cadence during free-living activities may aid in identifying individuals at elevated risk of developing slow habitual gait speed and, in the long term, OA.

OBJECTIVE

To assess differences in peak 1-minute cadence and weekly time in different cadence intensities between individuals with and without ACLR.

DESIGN

Cross-sectional study.

SETTING

Short-term, free-living conditions.

PATIENTS OR OTHER PARTICIPANTS

A total of 57 participants with ACLR (34 women, 23 men; age = 20.9 ± 3.2 years, time since surgery = 28.7 ± 17.7 months) and 42 healthy control participants (22 women, 20 men; age = 20.7 ± 1.7 years).

MAIN OUTCOME MEASURE(S)

Each participant wore a physical activity monitor for 7 days. Data were collected at 30 Hz, processed in 60-second epochs, and included in the analyses if the activity monitor was worn for at least 10 hours per day over 4 days. Mean daily steps, peak 1-minute cadence, and weekly minutes spent at 60 to 79 (slow walking), 80 to 99 (medium walking), 100 to 119 (brisk walking), ≥100 (moderate- to vigorous-intensity ambulation), and ≥130 (vigorous-intensity ambulation) steps per minute were calculated. One-way analyses of covariance were conducted to determine differences between groups, controlling for height and activity-monitor wear time.

RESULTS

Those with ACLR took fewer daily steps (8422 ± 2663 versus 10 033 ± 3046 steps; P = .005) and spent fewer weekly minutes in moderate- to vigorous-intensity cadence (175.8 ± 116.5 minutes versus 218.5 ± 137.1 minutes; P = .048) than participants without ACLR. We observed no differences in minutes spent at slow (ACLR = 77.4 ± 40.5 minutes versus control = 83.9 ± 34.3 minutes; P = .88), medium (ACLR = 71.6 ± 40.2 minutes versus control = 82.9 ± 46.8 minutes; P = .56), brisk (ACLR = 115.3 ± 70.3 minutes versus control = 138.3 ± 73.3 minutes; P = .18), or vigorous-intensity (ACLR = 24.3 ± 36.5 minutes versus control = 38.1 ± 60.9 minutes; P = .10) cadences per week.

CONCLUSIONS

Participants with ACLR walked approximately 40 fewer minutes per week in moderate- to vigorous-intensity cadence than participants without ACLR. Increasing the time spent at cadence ≥100 steps per minute and overall volume of physical activity may be useful as interventional targets to help reduce the risk of early development of OA after ACLR.

Sport specialization and sport participation opportunities and their association with injury history in female high school volleyball athletes

OBJECTIVE

Determine the association of sport specialization in female volleyball athletes with previous injury history and determine the association of sport specialization with volleyball participation opportunities.

DESIGN

Cross-sectional.

SETTING

Recruitment occurred from 83 Wisconsin high schools during the 2018 volleyball season.

PARTICIPANTS

Female volleyball athletes (N = 1,588, grades 9-12, age = 15.6 ± 1.1 years).

MAIN OUTCOMES

Participants completed a pre-season questionnaire soliciting information regarding 1) demographics, 2) sport specialization, 3) sport participation, and 4) sport-related injuries in the previous 12 months. Univariable logistic regression models were used to identify associations with previous injury. Chi-square analyses were used to investigate associations between sport specialization classification and other sport participation opportunities.

RESULTS

Both moderately and highly specialized athletes were more likely to report a previous injury compared to low specialized athletes (moderate OR: 1.84 [1.29-2.62]; p < 0.001 and high OR: 2.30 [1.64-3.24]; p < 0.001). Highly specialized athletes were more likely to report participating in club volleyball, summer tournaments, and training camps in the past 12 months. Participants who reported participating in club volleyball, summer competitions, and training camps last year were more likely to report an injury.

CONCLUSIONS

Specialization was associated with injury history and year-round volleyball opportunities among female adolescent volleyball athletes.

Length-Dependent Structural Transformations of Huntingtin PolyQ Domain Upon Binding to 2D-Nanomaterials

There is a strong negative correlation between the polyglutamine (polyQ) domain length (Q-length) in the intrinsically disordered Huntingtin protein (Htt) exon-1 and the age of onset of Huntington's disease (HD). PolyQ of Q-length longer than 40 has the propensity of forming very compact aggregate structures, leading to HD at full penetrance. Recent advances in nanobiotechnology provided a new platform for the development of novel diagnosis and therapeutics. Here, we explore the possibility of utilizing 2D-nanomaterials to inhibit the formation of supercompact polyQ structures through the so-called “folding-upon-binding” where the protein structure is dependent on the binding substrate. Using molecular dynamics simulations, we characterize two polyQ peptides with Q-length of 22 (Q22, normal length) and 46 (Q46, typical length causing HD) binding to both graphene and molybdenum disulfide (MoS₂) nanosheets, which have been applied as antibacterial or anticancer agents. Upon binding, Q22 unfolds and elongates on both grapheme and MoS₂ surfaces, regardless of its initial conformation, with graphene showing slightly stronger effect. In contrast, initially collapsed Q46 remains mostly collapsed within our simulation time on both nanosheets even though they do provide some “stretching” to Q46 as well. Further analyses indicate that the hydrophobic nature of graphene/MoS₂ promotes the stretching of polyQ on nanosheets. However, there is strong competition with the intra-polyQ interactions (mainly internal hydrogen bonds) leading to the disparate folding/binding behaviors of Q22 and Q46. Our results present distinct Q-length specific behavior of the polyQ domain upon binding to two types of 2D-nanomaterials which holds clinical relevance for Huntington's disease.

Commensal bacteria stimulate antitumor responses via T cell cross-reactivity

Recent studies show gut microbiota modulate antitumor immune responses; one proposed mechanism is cross-reactivity between antigens expressed in commensal bacteria and neoepitopes. We found that T cells targeting an epitope called SVYRYYGL (SVY), expressed in the commensal bacterium Bifidobacterium breve (B. breve), cross-react with a model neoantigen, SIYRYYGL (SIY). Mice lacking B. breve had decreased SVY-reactive T cells compared with B. breve-colonized mice, and the T cell response was transferable by SVY immunization or by cohousing mice without Bifidobacterium with ones colonized with Bifidobacterium. Tumors expressing the model SIY neoantigen also grew faster in mice lacking B. breve compared with Bifidobacterium-colonized animals. B. breve colonization also shaped the SVY-reactive TCR repertoire. Finally, SVY-specific T cells recognized SIY-expressing melanomas in vivo and led to decreased tumor growth and extended survival. Our work demonstrates that commensal bacteria can stimulate antitumor immune responses via cross-reactivity and how bacterial antigens affect the T cell landscape.

A Public BCR Present in a Unique Dual-Receptor-Expressing Lymphocyte from Type 1 Diabetes Patients Encodes a Potent T Cell Autoantigen

T and B cells are the two known lineages of adaptive immune cells. Here, we describe a previously unknown lymphocyte that is a dual expresser (DE) of TCR and BCR and key lineage markers of both B and T cells. In type 1 diabetes (T1D), DEs are predominated by one clonotype that encodes a potent CD4 T cell autoantigen in its antigen binding site. Molecular dynamics simulations revealed that this peptide has an optimal binding register for diabetogenic HLA-DQ8. In concordance, a synthetic version of the peptide forms stable DQ8 complexes and potently stimulates autoreactive CD4 T cells from T1D patients, but not healthy controls. Moreover, mAbs bearing this clonotype are autoreactive against CD4 T cells and inhibit insulin tetramer binding to CD4 T cells. Thus, compartmentalization of adaptive immune cells into T and B cells is not absolute, and violators of this paradigm are likely key drivers of autoimmune diseases.

Exploring Coaches' Perceptions of Youth Sport Specialization: A Comparison of High School and Club Sport Contexts

CONTEXT

Previous researchers have identified sport specialization as being associated with various negative outcomes (eg, overuse injuries and adverse psychosocial outcomes). However, little is known regarding how the underlying attitudes, beliefs, and values of sport stakeholders may be shaping this trend.

OBJECTIVE

To examine the perceptions of coaches in the high school versus club sport setting and compare their attitudes and behaviors toward sport specialization.

DESIGN

Cross-sectional survey.

PATIENTS OR OTHER PARTICIPANTS

A total of 769 coaches (497 high school coaches, 272 club sport coaches).

MAIN OUTCOME MEASURE(S)

Participants completed a novel measure that surveyed their perceptions regarding various aspects of youth sport specialization. Additionally, each coach completed a questionnaire detailing his or her relevant demographic and sport background information.

RESULTS

High school coaches and club sport coaches differed in their perceptions of sport specialization (t₇₆₇ = 1.41, P < .001); club coaches (2.43 ± 0.25) were more likely than high school coaches (2.31 ± 0.21) to rate specialization as a positive, adaptive practice. The multiple linear regression equations for both the high school and club coaches indicated that no educational, experiential, or demographic factors predicted coaches' perceptions of specialization (P values > .05).

CONCLUSIONS

Club sport coaches were more likely to possess attitudes in favor of sport specialization. Additionally, coaches' background characteristics did not predict their perceptions of specialization, suggesting that the competitive context itself (high school versus club) may be the most salient influencer of these perceptions. Athletes and sports medicine practitioners should be aware of the heightened expectation of specialized participation and resulting increased injury risk in these contexts. Pediatric sport researchers and practitioners should continue to explore how these different group perceptions manifest in participation behaviors and may link to overall athlete health, wellbeing, and development.

A Comparison of Emergency Preparedness Between High School Coaches and Club Sport Coaches

CONTEXT

Recent studies suggested that a large population of high school-aged athletes participate on club sport teams. Despite attempts to document emergency preparedness in high school athletics, the adherence to emergency and medical coverage standards among club sport teams is unknown.

OBJECTIVE

To determine if differences in emergency preparedness and training existed between coaches of high school teams and coaches of high school-aged club teams.

DESIGN

Cross-sectional survey.

SETTING

Online questionnaire.

PATIENTS OR OTHER PARTICIPANTS

A total of 769 coaches (females = 266, 34.6%) completed an anonymous online questionnaire regarding their emergency preparedness and training.

MAIN OUTCOME MEASURE(S)

The questionnaire consisted of (1) demographics and team information, (2) emergency preparedness factors (automated external defibrillator [AED] availability, emergency action plan [EAP] awareness, medical coverage), and (3) emergency training requirements (cardiopulmonary resuscitation/AED, first aid).

RESULTS

High school coaches were more likely than club sport coaches to be aware of the EAP for their practice venue (83.9% versus 54.4%, P < .001), but most coaches in both categories had not practiced their EAP in the past 12 months (70.0% versus 68.9%, P = .54). High school coaches were more likely to be made aware of the EAP during competitions (47.5% versus 37.1%, P = .02), but the majority of coaches in both categories indicated that they were never made aware of EAPs. High school coaches were more likely than club coaches to (1) have an AED available at practice (87.9% versus 58.8%, P < .001), (2) report that athletic trainers were responsible for medical care at practices (31.2% versus 8.8%, P < .001) and competitions (57.9% versus 31.2%, P < .001), and (3) be required to have cardiopulmonary resuscitation, AED, or first-aid training (P < .001).

CONCLUSIONS

High school coaches displayed much greater levels of emergency preparedness and training than coaches of high school-aged club teams. Significant attention and effort may be needed to address the lack of emergency preparedness and training observed in club coaches.

The Public Health Consequences of Sport Specialization

Sport specialization was thought to affect a relatively small number of elite athletes, but it is now a common practice in youth sport culture. Recent research in the field of sport specialization has led to a better understanding of the influence this issue is having on youth (ie, younger than 19 years of age) today. This review focuses on sport specialization from a public health perspective to elucidate the effect that this practice is having within the United States. The specific goals of this review are to describe (1) the prevalence of sport specialization and the factors that may affect the decision to specialize, (2) the costs of youth sport-related injuries in the context of sport specialization, (3) the financial costs that sport specialization has for families, and (4) how sport specialization may be affecting physical literacy.

Sport-Specific Associations of Specialization and Sex With Overuse Injury in Youth Athletes

BACKGROUND

Significant evidence has emerged that sport specialization is associated with an increased risk of overuse injury in youth athletes. Several recommendations exist to reduce the risk of overuse injury in youth sports, but the risk of overuse injuries may be dependent on specific movements required by a given sport.

HYPOTHESES

Associations between specialized sport participation and overuse injury will exist in volleyball athletes but not soccer or basketball athletes. Female athletes will be more likely to report an overuse injury in the previous year, regardless of sport.

STUDY DESIGN

Cross-sectional study.

LEVEL OF EVIDENCE

Level 3.

METHODS

Youth athletes between the ages of 12 and 18 years were recruited in-person at club team tournaments, competitions, and events around the state of Wisconsin during the 2016-2017 school year. Participants were asked to complete an anonymous questionnaire that consisted of (1) participant demographics, (2) sport specialization status, (3) monthly and weekly sport volume, and (4) sport-related injury history in the previous year.

RESULTS

A total of 716 youth athletes completed the questionnaire (70.8% female; mean age, 14.21 ± 1.50 years; 43.2% basketball, 19.4% soccer, 37.4% volleyball; 41.8% highly specialized; 32.3% reported overuse injury in the previous year). Sex was associated with overuse injury among basketball athletes, with female basketball athletes nearly 4 times more likely to report an overuse injury compared with male basketball athletes (odds ratio, [OR], 3.7; 95% CI, 2.1-6.6; P < 0.001). High specialization (OR, 2.3; 95% CI, 1.1-4.9; P = 0.02) and participating in a single sport for more than 8 months per year (OR, 2.0; 95% CI, 1.1-3.5; P < 0.05) were associated with overuse injury only among volleyball athletes.

CONCLUSION

Specialization and exceeding 8 months per year in a single sport was associated with overuse injury in volleyball, which is one of the most popular youth sports for female athletes. Specialization was not associated with overuse injury in basketball or soccer athletes. Female basketball athletes were nearly 4 times more likely to report a history of overuse injury compared with male basketball athletes. The sex of a youth athlete and the sport that he or she plays may influence the risk of overuse injury associated with sport specialization.

CLINICAL RELEVANCE

Youth athletes, parents, and clinicians should be aware that the potential risks of specialization might vary based on the athlete's sport and sex.

A Comparison of Team Sport Volume Surveyed Between High School and Club Sport Coaches

BACKGROUND

Club sport participation is increasingly common among high school athletes. Sport participation characteristics may vary widely between the high school and club sport settings. However, there have been no large-scale comparisons of sport participation volume between high school and club teams from similar sports.

PURPOSE/HYPOTHESIS

The purpose of this study was to compare the sport participation characteristics of high school and high school-aged club teams. We hypothesized that club team athletes would participate in more months per year and hours per week and would take more overnight trips than high school athletes and that club team coaches would be less likely to track their athletes' sport volume than high school coaches.

STUDY DESIGN

Cross-sectional study.

METHODS

A total of 769 coaches (266 female; 34.6%) from 3 sports (basketball, volleyball, soccer) completed an anonymous online questionnaire regarding their team's sport volume and their knowledge, attitudes, and beliefs regarding sport specialization. Coaches were eligible to participate if they had served as the head or assistant coach of a high school sport team or high school-aged club sport team in the past 12 months.

RESULTS

Overall, 64.6% (n = 497) were coaches of a high school team, and 35.4% (n = 272) were coaches of a club team with high school-aged athletes. Club coaches' teams played more months out of the year and took more overnight trips for competitions than high school coaches' teams but participated in fewer hours per week of practices or competitions during their season. There were no differences between club and high school coaches in tracking their athletes' sport volume, with most coaches in both settings reporting that they do not track the amount of time that their athletes participate in other sports.

CONCLUSION

Significant differences in sport participation volume exist between the teams of high school and club coaches.

Sport Participation and Specialization Characteristics Among Pediatric Soccer Athletes

Background:

Soccer is an increasingly popular sport for children and adolescents in the United States. Little is known about participation patterns related to sport specialization.

Purpose:

To investigate soccer participation levels and sport specialization characteristics among youth soccer athletes.

Study Design:

Cross-sectional study.

Methods:

Adolescent athletes aged between 12 and 18 years completed an online survey addressing participant demographics, sports and soccer participation history, and level of specialization. Descriptive analyses characterized participation, while chi-square and Kruskal-Wallis tests assessed the influence of specialization, sex, and grade on survey variables.

Results:

Overall, 83.7% of 746 respondents participated in an organized soccer league outside of school, and 37% played in multiple leagues concurrently. Nearly three-quarters of respondents trained in soccer more than 8 months of the year, with those who participated in club soccer being more likely to train more than 8 months of the year. More respondents were classified as high specialization (37.5%), followed by moderate (35.6%) and low (28.6%) specialization. No differences between sexes were noted for level of specialization or quitting other sports to specialize in soccer, but male athletes were more likely to train more than 8 months per year compared with female athletes. Respondents in older grades (9th-10th and 11th-12th grades) were more likely to be highly specialized and quit other sports to focus on soccer. No differences between grade levels were found among respondents training more than 8 months per year.

Conclusion:

The study findings suggest that many youth soccer athletes participated in multiple teams or leagues at the same time and trained more than 8 months of the year. Characteristics including participation on a club team, level of specialization, and male sex were associated with a greater likelihood of exceeding the 8-month training recommendation.

Exploring the binding mechanism between human profilin (PFN1) and polyproline-10 through binding mode screening

The large magnitude of protein-protein interaction (PPI) pairs within the human interactome necessitates the development of predictive models and screening tools to better understand this fundamental molecular communication. However, despite enormous efforts from various groups to develop predictive techniques in the last decade, PPI complex structures are in general still very challenging to predict due to the large number of degrees of freedom. In this study, we use the binding complex of human profilin (PFN1) and polyproline-10 (P10) as a model system to examine various approaches, with the aim of going beyond normal protein docking for PPI prediction and evaluation. The potential of mean force (PMF) was first obtained from the time-consuming umbrella sampling, which confirmed that the most stable binding structure identified by the maximal PMF difference is indeed the crystallographic binding structure. Moreover, crucial residues previously identified in experimental studies, W3, H133, and S137 of PFN1, were found to form favorable hydrogen bonds with P10, suggesting a zipping process during the binding between PFN1 and P10. We then explored both regular molecular dynamics (MD) and steered molecular dynamics (SMD) simulations, seeking for better criteria of ranking the PPI prediction. Despite valuable information obtained from conventional MD simulations, neither the commonly used interaction energy between the two binding parties nor the long-term root mean square displacement correlates well with the PMF results. On the other hand, with a sizable collection of trajectories, we demonstrated that the average and minimal rupture works calculated from SMD simulations correlate fairly well with the PMFs (R ² = 0.67), making this a promising PPI screening method.

Exploration of HIV-1 fusion peptide–antibody VRC34.01 binding reveals fundamental neutralization sites

VRC34.01 antibody binding to a vulnerable site of HIV envelope glycoprotein (Env), the gp41 fusion peptide, renders robust HIV neutralization, but several critical mutations decrease binding affinity and result in unbinding.

Lower Extremity Biomechanics Are Altered Across Maturation in Sport-Specialized Female Adolescent Athletes

Sport specialization is a growing trend in youth athletes and may contribute to increased injury risk. The neuromuscular deficits that often manifest during maturation in young, female athletes may be exacerbated in athletes who specialize in a single sport. The purpose of this study was to investigate if sport specialization is associated with increased lower extremity biomechanical deficits pre- to post-puberty in adolescent female athletes. Seventy-nine sport-specialized female adolescent (Mean ± SD age = 13.4 ± 1.8 years) basketball, soccer, and volleyball athletes were identified and matched with seventy-nine multi-sport (soccer, basketball, and volleyball) female athletes from a database of 1,116 female adolescent basketball, soccer, and volleyball athletes who were enrolled in one of two large prospective, longitudinal studies. The athletes were assessed over two visits (Mean ± SD time = 724.5 ± 388.7 days) in which they were classified as pre-pubertal and post-pubertal, respectively. Separate 2 × 2 analyses of covariance were used to compare sport-specialized and multi-sport groups and dominant/non-dominant limbs with respect to pubertal changes in peak knee sagittal, frontal, and transverse plane joint angular measures and moments of force recorded while performing a drop vertical jump task. The sport-specialized group were found to exhibit significantly larger post-pubertal increases in peak knee abduction angle (p = 0.005) and knee abduction moment (p = 0.006), as well as a smaller increase in peak knee extensor moment (p = 0.032) during landing when compared to the multi-sport group. These biomechanical changes are indicative of potentially compromised neuromuscular control that may increase injury risk pre- to post-puberty in sport-specialized female athletes. Consideration of maturation status may be an important factor in assessing the injury risk profiles of adolescent athletes who specialize in sport.

Sex differences in physical activity engagement after ACL reconstruction

OBJECTIVES

To investigate the effects of sex as an effect modifier of objectively measured moderate-to-vigorous physical activity (MVPA) in individuals following ACLR and healthy controls.

DESIGN

Cross-sectional research study.

SETTING

University community.

PARTICIPANTS

59 participants (42.4% male) with a history of ACLR and 55 healthy control participants (40.0% male).

MAIN OUTCOME MEASURES

Participants were outfitted with an ActiGraph wGT3X-BT accelerometer for a period of 7 days to assess MVPA. Weekly time engaged in MVPA (in bouts≥ 10 min), % of total time engaged in MVPA, and odds of meeting national physical activity guidelines (MVPA≥ 150 min/wk) were compared between males and females with a history of ACLR and healthy controls.

RESULTS

There were significant sex X group interactions for weekly MVPA (p = 0.02) and % total time in MVPA (p = 0.01). The odds of a female ACLR participant meeting national physical activity guidelines were significantly worse (X² = 4.18, OR = 2.54, CI₉₅ = 1.03-6.27) when compared to participants without ACLR.

CONCLUSIONS

Female participants with ACLR were found to be less active than healthy control participants and their odds of meeting national MVPA guidelines were also 2.54 times worse than healthy participants.

Sex Differences on the Landing Error Scoring System Among Individuals With Anterior Cruciate Ligament Reconstruction

CONTEXT: 

After anterior cruciate ligament reconstruction (ACLR), women have a greater risk of incurring a second anterior cruciate ligament injury and they display different landing movement patterns than men. It remains unclear if clinical movement-assessment tools, such as the Landing Error Scoring System (LESS), can detect sex differences in movement patterns after ACLR.

OBJECTIVE: 

To compare total LESS scores and individual LESS errors between men and women with a history of ACLR.

DESIGN: 

Cross-sectional study.

SETTING: 

Laboratory.

PATIENTS OR OTHER PARTICIPANTS: 

A total of 168 individuals (41 men and 127 women; mean age: men = 20 years [range, 19-25 years], women = 19 years [range, 18-20 years]; mean time since surgery: men = 21 months [range, 12-36 months], women = 27.5 months [range, 17-39 months]) with a history of primary, unilateral ACLR.

MAIN OUTCOME MEASURE(S): 

Participants completed a minimum of 3 trials of a drop vertical-jump task scored using the LESS. The between-sexes difference in LESS score was assessed using analysis of covariance, whereas the associations between participant sex and errors on each LESS item were assessed using logistic or multinomial regression.

RESULTS: 

Women displayed a greater number of total landing errors (men = 4.6 ± 2.3, women = 6.1 ± 2.3; P < .001) and were more likely to commit errors in trunk flexion at initial contact (men = 4.9%, women = 23.6%; odds ratio [OR] = 4.94), medial knee position at initial contact (men = 17.1%, women = 42.5%; OR = 6.01), medial knee displacement (men = 24.4%, women = 73.2%; OR = 7.88), total joint displacement (1 error: men = 58.5%, women = 71.7%, OR = 2.10; 2 errors: men = 7.3%, women = 14.2%, OR = 3.71), and overall impression (1 error: men = 75.6%, women = 84.3%, OR = 3.24; 2 errors: men = 2.4%, women = 10.2%, OR = 12.89) compared with men.

CONCLUSIONS: 

Women with ACLR displayed worse LESS scores and were more likely to commit errors related to medial knee displacement and overall landing quality than men with ACLR.

Sport Specialization and Risk of Overuse Injuries: A Systematic Review With Meta-analysis

CONTEXT

Sport specialization is theorized to increase the risk of sustaining overuse musculoskeletal injuries.

OBJECTIVE

To complete a systematic review and meta-analysis of the literature to determine if sport specialization is associated with overuse musculoskeletal injuries.

DATA SOURCES

An electronic search was conducted using the search terms "specialization," "year-round," "overuse," "repetitive stress," "injury," "young," "pediatric," and "sports."

STUDY SELECTION

Studies were included if their population was ≤18 years of age, if they compared athletes with high or single-sport specialization with athletes with low or multisport specialization, and focused on overuse injuries.

DATA EXTRACTION

Of the 12 articles that were identified for full-text review, 5 studies met all the inclusion criteria. Four studies provided adequate data for the meta-analysis. Quality scores on the modified Downs and Black scale ranged from 69% to 81%.

RESULTS

Athletes with high specialization were at an increased risk of sustaining an overuse injury compared with athletes with low (pooled relative risk [RR] ratio: 1.81; 95% confidence interval [CI]: 1.26-2.60) and moderate (pooled RR: 1.18; 95% CI: 1.05-1.33) specialization. Athletes with moderate specialization were at a higher risk of injury compared with athletes with low specialization (RR: 1.39 [95% CI: 1.04-1.87]).

LIMITATIONS

Four of the 5 studies included in this systematic review were included in the meta-analysis because of the lack of access to the original data set for 1 article.

CONCLUSIONS

Sport specialization is associated with an increased risk of overuse musculoskeletal injuries (Strength of Recommendation Taxonomy grade: B).