The relationship between self-concept clarity, athletic identity, athlete engagement and the mediating roles of quality of life and smartphone use in Chinese youth athletes

Background

Youth athletes represent the future of competitive sports, so examining their commitment to sport is critical. This study investigated the impacts of self-concept clarity and athletic identity on athlete engagement among Chinese youth athletes, and the mediating roles of quality of life and smartphone use.

Methods

410 youth athletes from sports schools completed an online cross-sectional survey measuring self-concept clarity, athletic identity, quality of life, smartphone use, and athlete engagement. We used convenience sampling. Instruments included validated scales like the Self-Concept Clarity Scale.

Results

The direct effect of self-concept clarity and athlete engagement in youth athletes was not significant (β = 0.04, p = 0.344), but there was a direct effect of athletic identity and athlete engagement (β = 0.61, p < 0.05). Quality of life mediated the relationships between self-concept clarity(indirect effect = -0.054, 95 % CI = -0.114, -0.019), athletic identity(indirect effect = 0.202, 95 % CI = 0.114, 0.349) and athlete engagement.

Conclusions

This study helps address gaps in understanding athlete engagement in youth athletes. The mediation model provides insights to improve self-concept clarity, athletic identity and quality of life to motivate greater engagement in youth athletes.

Mental health profiles among 13-16-year-Old Norwegian talent and mainstream students - A prospective person-centered analytical approach

OBJECTIVES

To contribute further knowledge about symptoms of anxiety, depression, body concerns, and self-worth among young talent development (TD) and mainstream students by exploring the indicators within-person combinations prospectively, aiming to identify distinct profiles.

METHODS

We included 946 students, n = 168 (45% girls) from three TD sports schools and one ballet class, n = 778 (52% girls) from ten mainstream schools. All were 13-14 years at T1 and 15-16 years at T2. Descriptive statistics were examined via variable-centered approaches: ANOVA and cross-tabulations. Mental health profiles were explored via person-centered approaches: latent profile and latent transition analysis, including profile stability over two years and school type, gender, and perfectionism association with profiles.

RESULTS

TD girls' and boys' anxiety and depression scores did not differ, but girls reported more weight-shape concerns. Mainstream schoolgirls fared worse compared to all others. Four retained profiles (distressed-body concerned, dissatisfied, moderate mentally healthy, mentally healthy) showed distinct patterns of co-occurring anxiety, depression, weight-shape concerns, and self-worth. Profile stability was high overall (72-93%). The highest proportion of TD boys was in the mentally healthy, TD girls and mainstream boys in moderate, and mainstream girls within the dissatisfied profile. Noteworthy transitions: TD boys who transitioned were likely changing to healthier profiles and girls to unhealthier. Unhealthier profiles were associated with socially prescribed perfectionism.

CONCLUSION

TD students fared relatively better than mainstream students. Still, considerable proportions of girls were identified in the unhealthiest profiles. These findings involving young TD and mainstream students propose a need for specific follow-up measures to promote mental health.

Youth Sport Coaches' Perceptions of Sexually Inappropriate Behaviors and Intimate Coach-Athlete Relationships

Although sexual harassment and abuse in youth sport have received increasing research attention worldwide, less is known about youth coaches' perceptions of sexually inappropriate behaviors and intimate relationships with athletes. The purpose of this exploratory study was to examine youth sport coaches' perceptions of behaviors that can lead to potential sexual harassment and abuse, as well as to understand how coaches perceive coach-athlete sexual relationships. A cross-sectional survey was completed by 200 male coaches from various U.S. youth sport programs. Overall, a majority of coaches indicated behaviors associated with sexist comments and verbal/physical advances as sexually inappropriate. There was, however, a lack of consensus regarding what constitutes sexually inappropriate behaviors when the behavior was instruction-related/contextually dependent. Results were mixed regarding the perceptions of coach-athlete sexual relationships, with a notable number of coaches agreeing that sexual intimacies with young athletes (17 years or younger) are not always harmful and should not be prohibited. Based on a regression analysis, white coaches were more likely to exhibit negative perceptions about coach-athlete sexual relationships compared to ethnically diverse coaches. Overall, these findings warrant the development or reevaluation of policies and interventions aimed at preventing sexual harassment and abuse in the youth sport environment. Continued research is needed to better understand youth sport coaches as the perpetrators of sexual harassment and abuse.

A test of the 2 × 2 Model of Perfectionistic Pressure in youth sport

Perfectionistic pressure from coaches and parents is likely to contribute to the development of perfectionism in youth athletes. However, if and how perfectionistic pressure from coaches and parents interact to predict the development of perfectionism is unknown. With this in mind, the present study tested a new model - the 2 × 2 Model of Perfectionistic Pressure - that focuses on the different combinations of perfectionistic pressure youth athletes can experience. Four within-person combinations of perfectionistic pressure are identified and compared: Pure coach pressure (high coach pressure/low parental pressure), pure parental pressure (low coach pressure/high parental pressure), mixed pressure (high coach pressure/high parental pressure), and low pressure (low coach pressure/low parental pressure). To test the model, a sample of 210 youth athletes (M age = 14.68 years) completed measures of perfectionistic strivings, perfectionistic concerns, coach pressure to be perfect, and parental pressure to be perfect. Moderated hierarchical regression and simple slopes analyses revealed that mixed pressure was related to the highest levels of both perfectionistic strivings and perfectionistic concerns. The findings provide initial evidence for the new model and suggests it will be useful in studying the development of perfectionism and other outcomes in sport.

Diffusion Imaging of Sport-related Repetitive Head Impacts-A Systematic Review

Repetitive head impacts (RHI) are commonly observed in athletes participating in contact sports such as American football, ice hockey, and soccer. RHI usually do not result in acute symptoms and are therefore often referred to as subclinical or "subconcussive" head impacts. Epidemiological studies report an association between exposure to RHI and an increased risk for the development of neurodegenerative diseases. Diffusion magnetic resonance imaging (dMRI) has emerged as particularly promising for the detection of subtle alterations in brain microstructure following exposure to sport-related RHI. The purpose of this study was to perform a systematic review of studies investigating the effects of exposure to RHI on brain microstructure using dMRI. We used the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) to determine studies that met inclusion and exclusion criteria across three databases. Seventeen studies were identified and critically evaluated. Results from these studies suggest an association between white matter alterations and RHI exposure in youth and young adult athletes. The most consistent finding across studies was lower or decreased fractional anisotropy (FA), a measure of the directionality of the diffusion of water molecules, associated with greater exposure to sport-related RHI. Whether decreased FA is associated with functional outcome (e.g., cognition) in those exposed to RHI is yet to be determined. This review further identified areas of importance for future research to increase the diagnostic and prognostic value of dMRI in RHI and to improve our understanding of the effects of RHI on brain physiology and microstructure.

Modeling lactate threshold in young squad athletes: influence of sex, maximal oxygen uptake, and cost of running

PURPOSE

This study aimed to investigate: 1. The influence of sex and age on the accuracy of the classical model of endurance performance, including maximal oxygen uptake ([Formula: see text]), its fraction (LT2_%), and cost of running (C_R), for calculating running speed at lactate threshold 2 (vLT2) in young athletes. 2. The impact of different C_R determination methods on the accuracy of the model. 3. The contributions of [Formula: see text], LT2_%, and C_R to vLT2 in different sexes.

METHODS

45 male and 55 female young squad athletes from different sports (age: 15.4 ± 1.3 years; [Formula: see text]: 51.4 ± 6.8 [Formula: see text]) performed an incremental treadmill test to determine [Formula: see text], LT2_%, C_R, and vLT2. C_R was assessed at a fixed running speed (2.8 [Formula: see text]), at lactate threshold 1 (LT1), and at 80% of [Formula: see text], respectively.

RESULTS

Experimentally determined and modeled vLT2 were highly consistent independent of sex and age (ICC [Formula: see text] 0.959). The accuracy of vLT2 modeling was improved by reducing random variation using individualized C_R at 80% [Formula: see text] (± 4%) compared to C_R at LT1 (± 7%) and at a fixed speed (± 8%). 97% of the total variance of vLT2 was explained by [Formula: see text], LT2_%, and C_R. While [Formula: see text] and C_R showed the highest unique (96.5% and 31.9% of total [Formula: see text], respectively) and common (- 31.6%) contributions to the regression model, LT2_% made the smallest contribution (7.5%).

CONCLUSION

Our findings indicate: 1. High accuracy of the classical model of endurance performance in calculating vLT2 in young athletes independent of age and sex. 2. The importance of work rate selection in determining C_R to accurately predict vLT2. 3. The largest contribution of [Formula: see text] and C_R to vLT2, the latter being more important in female athletes than in males, and the least contribution of LT2_%.

Neuromuscular characteristics of front and back legs in junior fencers

In elite fencers, muscle strength and muscle mass of the front leg (FL) are greater than those of the back leg (BL) due to characteristic physiological and biomechanical demands placed on each leg during fencing. However, the development of laterality in their neural and muscular components is not well-understood. The present study investigated neuromuscular characteristics of FL and BL in junior fencers. Nineteen junior fencers performed neuromuscular performance tests for FL and BL, separately. There were no significant differences in the isometric knee extension strength (MVC), unilateral vertical jump (UVJ), vastus lateralis muscle thickness (MT), or motor unit firing rate of the vastus lateralis muscle (MUFR) between FL and BL (p > 0.05). In subgroup analyses, a significantly greater MUFR in FL than BL was noted only in fencers with > 3 years of fencing experience, and significantly greater UVJ in FL than BL was observed solely in fencers with < 3 years of fencing experience (p < 0.05). Strong positive correlations between FL and BL were identified in MVC, MT, and MUFR in fencers with > 3 years of fencing experience, but not in those with < 3 years of experience. These findings suggest that in junior fencers, laterality in neuromuscular performance has not manifested, whereas longer fencing experience induces fencing-dependent laterality in neural components, and laterality in dynamic muscle strength is decreased with fencing experience.

Acute and long-term effects of two different static stretching training protocols on range of motion and vertical jump in preadolescent athletes

This study examined the acute and long-term effects of two static stretching protocols of equal duration, performed either as a single stretch or multiple shorter duration repetitions on hip hyperextension range of motion (ROM) and single leg countermovement jump height (CMJ). Thirty female gymnasts were randomly assigned to stretching (SG) or control groups (CG). The SG performed two different protocols of static stretching, three times per week for 9 weeks. One leg performed repeated stretching (3 × 30 s with 30 s rest) while the other leg performed a single stretch (90 s). The CG continued regular training. ROM and CMJ were measured pre- and 2 min post-stretching on weeks 0, 3, 6, 9, and 3 weeks into detraining. CMJ height increased over time irrespective of group (main effect time, p = 0.001), with no statistical difference between groups (main effect group, p = 0.272). Three-way ANOVA showed that, CMJ height after stretching was not affected by either stretching protocol at any time point (p = 0.503 to 0.996). Both stretching protocols equally increased ROM on weeks 6 (10.9 ± 13.4%, p < 0.001, d = 0.42), and 9 (21.5 ± 13.4%, p < 0.001, d = 0.78), and this increase was maintained during detraining (17.0 ± 15.0%, p < 0.001, d = 0.68). No increase in ROM was observed in the CG (p > 0.874). Static stretching of long duration applied either as single or multiple bouts of equal duration, results in similar acute and long-term improvements in ROM. Furthermore, both stretching protocols do not acutely affect subsequent CMJ performance, and this effect is not influenced by the large increase in ROM and CMJ overtime.

Characteristics of select and non-select U15 male soccer players

Baseline characteristics of 31 healthy male U15 soccer players who were classified as select or non-select at the end of the season were compared. Players were 14.4 ± 0.54 years (13.6–15.3 years) at baseline; characteristics included body size, proportions and composition, estimated maturity status, several functional capacities, and coach classifications of potential in the sport. Decisions regarding selection or non-selection were made about two months after baseline. Select and non-select U15 soccer players differed significantly in estimated maturity status, body size, proportions and estimated muscle mass, functional tests related to speed, power and strength, and coach evaluation of potential, specifically tactical skills on offense and skills associated with creativity and decision making. When age and biological maturity status were statistically controlled, select and non-select players differed significantly only on the vertical jump, grip strength, and coach ratings of tactical skills on offense and of creativity and decision making. Results of stepwise discriminant analysis highlighted the importance of coach evaluation of tactical skills associated with offense, and of power and strength in distinguishing select from non-select players. The results highlight the advantages of advanced biological maturity status among adolescent male soccer players and also the importance of coach perceptions of talent. The latter implies a need for further study of the basis of coach perceptions, specifically how they are influenced by and perhaps interact with player characteristics at different ages, and how the perceptions influence playing time and player behaviors and interactions.

Despite maintaining a high daily training availability, a quarter of athletes start the season injured and three quarters experience injury in an Australian State Academy of Sport

OBJECTIVES

To 1) investigate the incidence, prevalence, burden and characteristics of injuries; and 2) explore the frequency of physiotherapy and medical servicing for elite sports academy athletes over a 12-month season.

DESIGN

Prospective cohort study.

METHODS

Medical attention and time-loss injuries were prospectively recorded by Physiotherapy and Medical (Sports Physician) staff for 94 athletes (72.3% females). The number of linked physiotherapy and medical servicing appointments was also recorded. Injury incidence rates (IIR), point and period prevalence, and injury burden were calculated and compared by athlete gender, sport, and categorisation (performance level) using incidence rate ratios (IRR).

RESULTS

The number of injuries reported was 193 in 71 (75.5%) athletes. The IIR was 2.1 (95%CI: 1.8 to 2.4) injuries per 365 days, with no gender difference observed (IRR: 1.1, 0.8 to 1.4). The injury burden was 43.5 (95%CI: 37.8 to 50.1) days absent per 365 days. More than one-quarter (point prevalence, 26.6%) of athletes commenced the season with an injury. In-season injury risk was 2.5 fold greater in athletes who started the season with an injury compared to athletes who started the season without an injury (IRR: 2.5, 1.9 to 3.4). The majority (81.2%) of the 1164 appointments recorded were physiotherapy, with an overall 4.3:1.0 physiotherapy to medical appointment ratio.

CONCLUSIONS

One in four athletes began the elite pathway season with a pre-existing injury, while also demonstrating a 2.5 fold greater risk of subsequent injury in the scholarship period. Sports should not assume their athletes are uninjured at the beginning of their scholarship. Injury profiles, and physiotherapy and medical servicing varied across sports. To reduce health as a barrier in the successful transition of talented young athletes to elite athletes, injury management strategies at the commencement of recruitment and throughout the scholarship should be prioritised in the development pathway.

REPIMPACT - a prospective longitudinal multisite study on the effects of repetitive head impacts in youth soccer

Repetitive head impacts (RHI) are common in youth athletes participating in contact sports. RHI differ from concussions; they are considered hits to the head that usually do not result in acute symptoms and are therefore also referred to as “subconcussive” head impacts. RHI occur e.g., when heading the ball or during contact with another player. Evidence suggests that exposure to RHI may have cumulative effects on brain structure and function. However, little is known about brain alterations associated with RHI, or about the risk factors that may lead to clinical or behavioral sequelae. REPIMPACT is a prospective longitudinal study of competitive youth soccer players and non-contact sport controls aged 14 to 16 years. The study aims to characterize consequences of exposure to RHI with regard to behavior (i.e., cognition, and motor function), clinical sequelae (i.e., psychiatric and neurological symptoms), brain structure, function, diffusion and biochemistry, as well as blood- and saliva-derived measures of molecular processes associated with exposure to RHI (e.g., circulating microRNAs, neuroproteins and cytokines). Here we present the structure of the REPIMPACT Consortium which consists of six teams of clinicians and scientists in six countries. We further provide detailed information on the specific aims and the design of the REPIMPACT study. The manuscript also describes the progress made in the study thus far. Finally, we discuss important challenges and approaches taken to overcome these challenges.

Postural stability in athletes: The role of sport direction

BACKGROUND

The bulk of relevant studies compare individual or very few sports and on small samples of athletes. This requires extensive analysing postural stability in various sports.

RESEARCH QUESTION

The main objective of our study was to identify the features of postural stability in a normal vertical stance in athletes of various kinds.

METHODS

This study compares postural stability in a normal bipedal stance with eyes open (EO) and eyes closed (EC) conditions among athletes (n = 936, age: 6-47 years) from different sports and performance level. Postural stability was measured through the center of pressure (COP) sway area (AS) and velocity (VCP) while standing quietly in a normal bipedal position with EO and EC on a stabiloplatform (50 Hz).

RESULTS

The order of VCP-EO increase in athletes compared to Control was as follows: Shooting (-11.3 %, p < .0001) < Football (-10.4 %, p < .0001) < Boxing (-8.7 %, p < .0001) < Cross-Country Skiing (-7.2 %, p < .0001) < Gymnastics (-7.0 %, p < .0001) < Running (-6.9 %, p < .0001) < Team Games Played with Hands (-6.8 %, p < .0001) < Wrestling (-6.3 %, p < .0001) < Tennis (-5.5 %, p = .0004) < Alpine Skiing (-5.4 %, p = .002) < Rowing (-5.0 %, p = .194) < Speed Skating (-4.7 %, p = .004) < Figure Skating (-3.6 %, p = .034) < Control.

SIGNIFICANCE

Practicing any kind of sport was associated with increased postural stability in normal bipedal stance. This is the first study that provides reference values of COP sway and velocity with and without visual control on a stable force platform for different sport groups.

The standing knee lift test is not a useful screening tool for time loss from low back pain in youth basketball and floorball players

OBJECTIVES

The aim of this study was to investigate the association between pelvic kinematics during the standing knee lift (SKL) test and low back pain (LBP) in youth floorball and basketball players.

DESIGN

A prospective cohort study.

SETTING

Finnish elite youth floorball and basketball players.

PARTICIPANTS

Finnish elite youth female and male floorball and basketball players (n = 258, mean age 15.7 ± 1.8).

MAIN OUTCOME MEASURES

LBP resulting in time loss from practice and games was recorded over a 12-month period and verified by a study physician. Associations between LBP and sagittal plane pelvic tilt and frontal plane pelvic obliquity during the SKL test as measured at baseline were investigated. Individual training and game hours were recorded, and Cox's proportional hazard models with mixed effects were used for the analysis.

RESULTS

Cox analyses revealed that sagittal plane pelvic tilt and frontal plane pelvic obliquity were not associated with LBP in floorball and basketball players during the follow-up. The hazard ratios for pelvic tilt and pelvic obliquity ranged between 0.93 and 1.08 (95% CIs between 0.91 and 1.07 and 0.83 and 1.29), respectively.

CONCLUSIONS

Pelvic movement during the SKL test is not associated with future LBP in youth floorball and basketball players.

Developmental fitness curves: assessing sprint acceleration relative to age and maturity status in elite junior tennis players

BACKGROUND

The influence of maturity-status on athletic performance is reasonably well-documented. Methodological and practical issues of assessment and lack of longitudinal data have impacted the success of various models.

AIM

To develop age- and sex-specific developmental curves for sprint acceleration in elite youth tennis players and to address variation in performance relative to chronological and biological age.

SUBJECTS AND METHODS

Measures of acceleration were available for 3120 elite youth tennis players aged 8-15 years attending National and Regional Talent Identification days. Variation in acceleration by chronological and estimated biological ages was evaluated in corresponding data for an independent sample of elite youth players 8.9 to 15.1 years of age.

RESULTS

Acceleration varied as a function of chronological and biological age relative to developmental curves. Early maturing males and females had significantly poorer performances when acceleration was considered relative to biological age. Significant discrepancy in percentiles relative to biological versus chronological ages was also evident between early and late maturing players of each sex.

CONCLUSION

Evaluating performance relative to developmental curves and maturity status may be a practical means of monitoring long-term athlete development in tennis.

Assessment of HEADS UP online training as an educational intervention for sports officials/athletic trainers

BACKGROUND

Sports- and recreation-related concussions are a common injury among children. Sports officials (SOs) and athletic trainers (ATs) are integral to setting the stage for safe play and managing concussions when they occur, and significant numbers of both groups have completed the Centers for Disease Control and Prevention's HEADS UP online concussion training course. However, the utility of the course for these audiences has not been assessed. We hypothesized that sports officials' and athletic trainers' concussion-related knowledge, attitudes, and behavioral intentions will improve from pre- and post-test after completing CDC's HEADS UP online concussion training course.

METHOD

Respondents' concussion-related knowledge, attitudes, and behavioral intentions were assessed both before and after taking the training course. Differences between pre- and post-test scores were calculated based on the Wilcoxon Signed Rank Test Z-score or McNemar's test. Effect sizes were interpreted.

RESULTS

The SOs and ATs who participated in the HEADS UP online training had a high level of concussion knowledge before taking the course: 90% or more of respondents could identify the correct response for at least seven of the 13 knowledge questions in the pre-test. Still, the course was effective at improving the respondents' knowledge about return-to-play protocols and concussion reporting. Further, SOs and ATs demonstrated improvement in their concussion-related attitudes and behavioral intentions between the pre- and post-test.

CONCLUSION

SOs' and ATs' concussion knowledge, attitudes, and behavioral intentions improved immediately following completion of the CDC HEADS UP online training. Future research could also focus on the long-term retention of this type of training. Practical Applications: This study provides insight into how to better focus concussion-related educational programs to fit SOs' and ATs' needs.

Nutritional knowledge of youth academy athletes

Background

Youth athletes are under increasing pressures to excel in their chosen sport and many turn to nutritional supplements in order to enhance sports performance. However, athletes may obtain their nutritional information via illegitimate sources such as the internet, media, and other athletes, representing miscommunication between sound scientific information and anecdotal experiences. The objective of this investigation was to examine nutrition knowledge of elite youth athletes from a non-residential regional academy of sport.

Methods

A previously validated two-part nutrition knowledge questionnaire (NKQ) was administered to 101 (37 male and 64 female) non-residential regional Academy of Sport elite youth athletes at an annual training camp. Part 1 of the NKQ presented demographic questions. Part 2 presented 90 sports nutrition knowledge questions in seven knowledge subcategories (1) Nutrients; (2) Dietary reference intakes (DRI); (3) Fluids/Hydration; (4) Recovery; (5) Weight gain; (6) Weight loss; and (7) Supplements.

Results

The mean NKQ score of all athletes was 43.8% (± 11.4). No gender differences observed between nutritional knowledge total scores, however female athletes recorded more 'correct' responses than males (p = 0.02) in the Nutrients subcategory. Majority of athletes had difficulty identifying correct DRI with this subcategory featuring the lowest percentage of 'correct' to 'incorrect' responses (27.1% ± 2.3; p = 0.02). Supplements subcategory displayed much uncertainty with significantly more 'unsure' than 'incorrect' responses (42.4% ± 20.3; p < 0.05).

Conclusions

In agreement with previous research, results of the current study indicate that elite youth athletes lack fundamental nutritional knowledge, specifically related to DRI and supplementation. These data provide further support of current recommendations that Academy of Sport youth athletes may benefit from integrated nutrition education conducted by qualified nutrition professionals.

Modifying bowling kinematics in cricket pace bowlers with exercise-based injury prevention: A cluster-randomised controlled trial

OBJECTIVES

Undesirable bowling kinematics can increase the risk of low back injury. This study investigated if an exercise-based injury prevention program (IPP) could modify bowling kinematics in community-level adolescent pace bowlers.

DESIGN

Cluster-randomised controlled trial.

METHODS

Pace bowlers from eight cricket organisations were cluster-randomised into an intervention or control group. At baseline and follow-up sessions biomechanical bowling data were collected. Between sessions, the intervention group completed an eight-week IPP while the control continued their normal cricket activity. Treatment effects (95% CI) were estimated with linear mixed models.

RESULTS

There were significant treatment effects favouring the intervention group for shoulder counter-rotation (-3.8°; -7.2° to -0.3°) and lateral trunk flexion relative to the pelvis (-2.2°; -4.0° to -0.5°). Shoulder counter-rotation also increased in the control group by 2.2° (Cohen's d=0.22). There were no effects of the intervention on: lateral trunk flexion at front foot contact (FFC) (1.2°; -2.5° to 4.8°), lateral trunk flexion at ball release (BR) (-0.5°; -3.0° to 2.0°), pelvis rotation at FFC (0.9°; -4.0° to 2.2°), pelvis rotation at BR (-1.1°; -5.7° to 3.6°), front hip angle at FFC (1.6°; -3.6° to 6.7°), front hip angle at BR (-1.6°; -5.0° to 1.9°), front knee angle at FFC (-1.1°; -4.5° to 2.3°), front knee angle at BR (1.7°; -5.6° to 9.1°), or ball velocity (1.1kmh^-1; -7.5kmh^-1 to 9.7kmh^-1).

CONCLUSIONS

The IPP maintained shoulder counter-rotation and lateral trunk flexion relative to the pelvis in the intervention group and this could attenuate injury risk. No treatment effects were observed for lower-limb kinematics.

The Australian Institute of Sport framework for rebooting sport in a COVID-19 environment

Sport makes an important contribution to the physical, psychological and emotional well-being of Australians. The economic contribution of sport is equivalent to 2-3% of Gross Domestic Product (GDP). The COVID-19 pandemic has had devastating effects on communities globally, leading to significant restrictions on all sectors of society, including sport. Resumption of sport can significantly contribute to the re-establishment of normality in Australian society. The Australian Institute of Sport (AIS), in consultation with sport partners (National Institute Network (NIN) Directors, NIN Chief Medical Officers (CMOs), National Sporting Organisation (NSO) Presidents, NSO Performance Directors and NSO CMOs), has developed a framework to inform the resumption of sport. National Principles for Resumption of Sport were used as a guide in the development of 'the AIS Framework for Rebooting Sport in a COVID-19 Environment' (the AIS Framework); and based on current best evidence, and guidelines from the Australian Federal Government, extrapolated into the sporting context by specialists in sport and exercise medicine, infectious diseases and public health. The principles outlined in this document apply to high performance/professional, community and individual passive (non-contact) sport. The AIS Framework is a timely tool of minimum baseline of standards, for 'how' reintroduction of sport activity will occur in a cautious and methodical manner, based on the best available evidence to optimise athlete and community safety. Decisions regarding the timing of resumption (the 'when') of sporting activity must be made in close consultation with Federal, State/Territory and/or Local Public Health Authorities. The priority at all times must be to preserve public health, minimising the risk of community transmission.

Performance in dynamic movement tasks and occurrence of low back pain in youth floorball and basketball players

BACKGROUND

Prospective studies investigating risk factors for low back pain (LBP) in youth athletes are limited. The aim of this prospective study was to investigate the association between hip-pelvic kinematics and vertical ground reaction force (vGRF) during landing tasks and LBP in youth floorball and basketball players.

METHODS

Three-hundred-and-eighty-three Finnish youth female and male floorball and basketball players (mean age 15.7 ± 1.8) participated and were followed up on for 3 years. At the beginning of every study year the players were tested with a single-leg vertical drop jump (SLVDJ) and a vertical drop jump (VDJ). Hip-pelvic kinematics, measured as femur-pelvic angle (FPA) during SLVDJ landing, and peak vGRF and side-to-side asymmetry of vGRF during VDJ landing were the investigated risk factors. Individual exposure time and LBP resulting in time-loss were recorded during the follow-up. Cox's proportional hazard models with mixed effects and time-varying risk factors were used for analysis.

RESULTS

We found an increase in the risk for LBP in players with decreased FPA during SLVDJ landing. There was a small increase in risk for LBP with a one-degree decrease in right leg FPA during SLVDJ landing (HR 1.09, 95% CI 1.02 to 1.17, per one-degree decrease of FPA). Our results showed no significant relationship between risk for LBP and left leg FPA (HR 1.04, 95% CI 0.97 to 1.11, per one-degree decrease of FPA), vGRF (HR 1.83, 95% CI 0.95 to 3.51) or vGRF side-to-side difference (HR 1.22, 95% CI 0.65 to 2.27) during landing tasks.

CONCLUSIONS

Our results suggest that there is an association between hip-pelvic kinematics and future LBP. However, we did not find an association between LBP and vGRF. In the future, the association between hip-pelvic kinematics and LBP occurrence should be investigated further with cohort and intervention studies to verify the results from this investigation.

LEVEL OF EVIDENCE

Prognosis, level 1b.

Exercise-based injury prevention for community-level adolescent cricket pace bowlers: A cluster-randomised controlled trial

OBJECTIVES

To investigate if an exercise-based injury prevention program (IPP) can modify risk factors for injury in community-level adolescent cricket pace bowlers.

DESIGN

Cluster-randomised controlled trial.

METHODS

Eight cricket organisations (training two times per week and no previous involvement in a structured IPP) participated in this cluster-randomised trial. Participants were aged 14-17 years, injury free, and not currently performing a rehabilitation/exercise program. Cricket organisations (clusters) were block-randomised by computerised number generation into an intervention group (performed an eight-week IPP at training) or control group (continued their usual cricket activity). Participants were not blinded to group allocation. Strength, endurance, and neuromuscular control were assessed at baseline and follow-up. Treatment effects were estimated using linear mixed models.

RESULTS

Sixty-five male adolescent pace bowlers (intervention n=32 and control n=33) were randomised. There were significant treatment effects favouring the intervention group for shoulder strength (90°/s) 0.05 (95% CI 0.02-0.09) Nm/kg, hamstring strength (60°/s) 0.32 (95% CI 0.13-0.50) Nm/kg, hip adductor strength dominant 0.40 (95% CI 0.26-0.55) Nm/kg and non-dominant 0.33 (95% CI 0.20-0.47) Nm/kg, SEBT reach distance dominant 3.80 (95% CI 1.63-6.04) percent of leg length (%LL) and non-dominant 3.60 (95% CI 1.43-5.78) %LL, and back endurance 20.4 (95% CI 4.80-36.0) seconds. No differences were observed for shoulder strength (180°/s) (p=0.09), hamstring strength (180°/s) (p=0.07), lumbopelvic stability (p=0.90), and single leg squat knee valgus angle (dominant p=0.06, non-dominant p=0.15).

CONCLUSIONS

Exercise-based IPPs can modify risk factors for injury in community-level adolescent pace bowlers. Future research is needed to confirm if IPPs can also reduce injury risk in this population.

Sex-specific relationships among iron status biomarkers, athletic performance, maturity, and dietary intakes in pre-adolescent and adolescent athletes

Background

The purpose of this study was to examine relationships among biomarkers of iron status, athletic performance, growth and development, and dietary intakes in pre-adolescent and adolescent male and female athletes.

Methods

Two-hundred and forty-nine male (n = 179) (mean ± standard deviation for age = 12.0 ± 2.1 years, height = 156.3 ± 13.9 cm, and weight = 49.1 ± 16.5 kg) and female (n = 70) (12.0 ± 2.2 years, 152.4 ± 12.3 cm, 45.3 ± 14.5 kg) athletes volunteered for capillary blood sample, anthropometric, athletic performance, and dietary intake assessments. Outcomes included maturity offset from peak height velocity, percent body fat, estimated muscle cross-sectional areas, vertical jump height (VJ), broad jump distance (BJ), pro-agility time (PA), L-cone time, 20-yard dash time (20YD), power push up (PPU) force, dietary intakes, and ferritin, soluble transferrin receptor (sTfR), and hemoglobin (Hb) concentrations.

Results

Athletic performance was consistently correlated with Hb in males (r = .237–.375, p < 0.001–0.05) and with sTfR (r = .521–.649, p < 0.001–0.004) and iron intake (r = .397–.568, p = 0.001–0.027) in females. There were no relationships between dietary intakes and ferritin, sTfR, or Hb (p > 0.05). After partialing out age and height, VJ, PA, LC, and 20YD remained correlated with Hb in males (|r_Hb,y.Age| = .208–.322, p = 0.001–0.041; |r_Hb,y.Height| = .211–.321, p = 0.001–0.038). After partialing out iron intake, PA and LC remained correlated with sTfR in females (|r_{sTfR,y.ironintake}| = .516–.569, p = 0.014–0.028).

Conclusions

Iron status biomarkers demonstrated sex-specific relationships with anaerobic exercise performance in youth athletes, which may be more dependent on maturity status and dietary intake than age. Moderate relationships between sTfR and athletic performance in adolescent female athletes emphasizes the importance of iron intake in this demographic.

Effects of different repeated sprint-training frequencies in youth soccer players

The aim of this study was to determine the effects of 2 different repeated-sprint ability (RSA) training frequencies (2 RSA sessions per week [RSA2D] or 1 RSA session [RSA1D]) under volume-equated conditions on sprint and RSA performance in under-15 (U15) soccer players. Twenty-seven youth male soccer players (age: 12.29±0.47 years; height: 158.35±10.86 cm; weight: 45.08±8.05 kg) were randomly assigned to RSA2D (n=14) or RSA1D (n=13) groups. The players performed the same RSA training for 6 weeks, and only the training frequency differed between the groups. Before and after the training period, 5 m sprint, 10 m sprint, 20 m sprint and the RSA test were assessed. No significant time × group interactions were observed (p>0.05). Within-group analysis showed significant improvements in 20 m sprint (p=0.046, partial eta squared [η _p ² ] = 0.150, large) and RSA average time (p=0.001, η _p ² =0.438, large), fastest time (p=0.012, η _p ² =0.229, large), and total time (p=0.001, η _p ² =0.438, large) from pre-test to post-test in RSA1D and RSA2D groups. However, no significant pre-post changes (p>0.05) were found in 5 m and 10 m sprint tests. In the between-group analysis, there were no significant differences between RSA1D and RSA2D groups in any variable. In conclusion, the current findings suggest that 6 weeks of RSA training 1 or 2 times per week in addition to typical soccer training produced significant and similar improvements in sprint and RSA performances. This information could be useful for coaches when planning training sessions during congested fixtures of soccer competitions or in periods when the emphasis should be placed on other physical qualities.

Balance control in youth hockey players with and without a history of concussions during a lower limb reaching task

BACKGROUND

Sport-related concussion (SRC) is a functional injury that affects several clinical domains, including balance and cognition. The purpose of this study was, 1) to determine whether a lower limb visuomotor task could identify balance control differences between youth athletes with and without previous SRC; and 2) if balance is affected by training over time.

METHODS

Youth hockey players (n = 34) who reported previous SRC (CONCUSSED; n = 12; mean age = 14.4 yrs., SD = 1.6, mean time from injury = 1.9 yrs., median = 1.7 yrs. [0.6-4.6]) and no history of SRC (CONTROL; n = 22; mean age = 14.7, SD = 1.5) were tested twice over 70 days. Participants stood in single support on a Nintendo Wii Balance board sampled at 100 Hz and performed Go/No-Go tasks with each foot. Five FitLight Trainer™ (Aurora, ON) lights were arranged on the floor at 60°, 30°, and 0° and illuminated in random GREEN (Go) or RED (No-Go). Balance was assessed using root mean square displacement and velocity of CoP in anterior-posterior and medial-lateral directions.

FINDINGS

CONCUSSED had significantly lower velocity of CoP in the anterior-posterior (F_{(1, 32)} = 13.81, p < .001) and medial-lateral (F_{(1, 32)} = 13.80, p < .001) directions than CONTROL, with no learning effects over time (anterior-posterior: F_{(1, 32)} = 0.30, p = .137: F_{(1, 32)} = 0.91, p = .346; medial-lateral: F_{(1, 32)} = 0.91, p = .346). These findings suggest that CONCUSSED consistently performed the task more conservatively.

INTERPRETATION

A lower limb Go/No-Go task may objectively identify differences between youth athletes with and without previous SRC. These visuomotor and balance control deficits may persist beyond clinical recovery.

Cross-Sectional Analysis Investigating the Concordance of Maturity Status Classifications in Elite Caucasian Youth Tennis Players

BACKGROUND

To evaluate the concordance of skeletal age (SA) with two predicted estimates of biological maturity status in elite British youth tennis players.

METHOD

Participants were 71 male and female elite youth tennis players aged 8 to 16 years. Weight, height, and sitting height were measured. SA (Fels method) was the criterion indicator of maturity status. Maturity status was predicted with two methods: predicted age at peak height velocity and percentage of predicted adult height at the time of observation. Players were classified as late, average (on time), or early maturing with each method. Concordance of classifications was evaluated with kappa coefficients and Spearman's rank order correlations.

RESULTS

Kappa coefficients between maturity status classifications were low in both sexes, - 0.11 to 0.22, while Spearman's rank order correlations between maturity status classifications based on SA and the percentage of predicted mature height were moderate in males (0.35) and females (0.25), but the corresponding correlations based on predicted age at peak height velocity (PHV) varied, moderate and negative in boys (- 0.37) and low and positive in girls (0.11). Concordance of maturity status classifications based on the prediction methods and SA among tennis players was thus limited.

CONCLUSIONS

Maturity status based on the percentage of predicted mature height at the time of observation correlated better with maturity status based on SA in contrast to status based on predicted age at PHV in this sample of elite youth tennis players.

Motivation for sports participation, injury prevention expectations, injury risk perceptions and health problems in youth floorball players

PURPOSE

Describe the motivation for floorball participation, injury prevention expectations, injury risk perceptions and prevalence of health problems in youth floorball players at the start of the season.

METHODS

This cross-sectional survey is part of a larger Sport Without Injury ProgrammE (SWIPE) project and provides baseline data before a cluster randomised controlled trial of an injury prevention program (Knee Control). A baseline survey (online and paper based) was collected from 47 teams with 471 youth floorball players from two provinces of Sweden before the start of the 2017 season.

RESULTS

The mean age for 140 females and 331 males was 13.7 (± 1.5) and 13.3 (± 1.0) years, respectively. The two most significant motivators for floorball participation were being part of the team (82% females, 75% males) and friends (65% females, 70% males). Fractures (84% females, 90% males), eye injuries (90% females, 83% males) and concussion (82% females, 83% males) were perceived as the most severe injuries. 93% of players believed that sports injuries can be prevented, while 74% believed it is unlikely that they will sustain an injury. Existing health problems at the beginning of the season were prevalent in 33% of players, with 65% being injuries and 35% illnesses. 17% of existing injuries at the start of the season caused time-loss from play and 17% required medical attention.

CONCLUSION

Social aspects were the greatest motivators for floorball participation in youths, suggesting that these factors are important to retain sports participants. The high number of health problems in youth is a concern; as such more effort, resources and priority should be given to sports safety programs. Many players believed that sports injuries can be prevented, possibly providing a fertile ground for implementation of such programs.

LEVEL OF EVIDENCE

IV.

Limb symmetry index in competitive alpine ski racers: Reference values and injury risk identification according to age-related performance levels

PURPOSE

The aims of this study were to assess differences of limb symmetry index (LSI) in strength- and coordination-related tasks between high-level, competitive, noninjured ski racers of different age-related performance levels and to prospectively assess limb differences as a possible risk factor for traumatic and overuse injury in youth ski racers.

METHODS

The study (Study 1) included 285 high-level competitive ski racers (125 females, 160 males) of 3 age-related performance levels and based on the school system: 95 youth (10-14 years, secondary modern school), 107 adolescent (15-19 years, grammar school), and 83 elite athletes (20-34 years). To investigate the second aim (Study 2), 67 of the 95 youth athletes were included and any traumatic or overuse injuries were prospectively recorded over 2 seasons. All athletes performed 4 unilateral tests (strength related: one-leg counter movement jump (OL-CMJ) and one-leg isometric/isokinetic press strength test (OL-ILS); coordination related: one-leg stability test (OL-ST) and one-leg speedy jump test (OL-SJ)). The LSI was calculated by dividing the dominant leg by the nondominant leg and multiplying by 100. Kruskal-Wallis H tests and binary logistic regression analyses were conducted.

RESULTS

There were significant differences between the LSI of the 3 age-related performance-level groups only in the strength-related tests: the OL-CMJ (χ²(2, 285) = 9.09; p = 0.01) and the OL-ILS (χ²(2, 285) = 14.79; p < 0.01). The LSI for OL-ILS was found to be a significant risk factor for traumatic injury in youth ski racers (Wald = 7.08; p < 0.01). No significant risk factors were found for overuse injuries.

CONCLUSION

Younger athletes display slightly greater LSI values only in the strength-related tests. The cut-off value of limb differences of <10% for return to sport decisions seems to be appropriate for elite athletes, but for youth and adolescent athletes it has to be critically discussed. It seems to be necessary to define thresholds based on specific performance tasks (strength vs. coordination related) rather than on generalizations, and age-related performance levels must be considered. Limb differences in unilateral leg extension strength represent a significant injury risk factor in youth ski racers.

Relative age effect: Characteristics of youth soccer players by birth quarter and subsequent playing status

PURPOSE

To compare characteristics of club level male soccer players 11 and 13 years of age, and to evaluate playing status in soccer two and 10 years after baseline by birth quarter (BQ).

METHODS

Youth players 11 (n = 62, born 1992, observed December 2003) and 13 (n = 50, born 1990, observed April 2004) years were grouped by BQ. Baseline data included stature, weight, maturity status, functional capacities, soccer skills, goal orientation, and coach evaluation of potential. Playing status in soccer in 2006 and 2014 was also available. Baseline characteristics and subsequent playing status were compared by BQ.

RESULTS

Baseline characteristics did not differ by BQ except for age and percentage of predicted adult height. Though not significant, coaches tended to rate players in BQ1as higher in potential. For those competing in soccer as adults, BQ2 (4), BQ3 (5) and BQ4 (2) were represented among players11 years, and BQ1 (3), BQ2 (2), BQ3 (1) and BQ4 (4) among players 13 years.

CONCLUSION

Although limited to small numbers, differences among players by BQ were inconsistent. The results indicate a need to extend potential explanations of the RAE to include behavioral variables, coaches, training environment, and perhaps the culture of the sport.

Prediction of life stress on athletes' burnout: the dual role of perceived stress

Although many studies adopted Smith's (1986) cognitive-affective model of athletic burnout in examining stress-burnout relationship, very few studies examined the mediating/moderating role of perceived stress on the stress-burnout relationship. We sampled 195 college student-athletes and assessed their life stress, perceived stress, and burnout. Correlation analyses found all study variables correlated. Two separate hierarchical regression analyses found that the "distress" component of perceived stress mediated athletes' two types of life stress-burnout relationship but "counter-stress" component of perceived stress-moderated athletes' general-life stress-burnout relationship. We concluded that interweaving relationships among athletes' life stress, perceived stress, and burnout are not straightforward. Future research should consider the nature of athletes life stress, and dual role of perceived stress in examining its' association with related psychological responses in athletic settings.

Physical activity outside of organised sports is associated with functional performance

AIM

The purpose of this study was to determine whether high levels of strenuous physical activity outside of organised sports are associated with better functional test performance.

METHODS

Youth athletes (n = 445, mean = 14.2 ± 2.5 years) reported their frequency of strenuous physical activity outside of organised sports. The functional performance tests: vertical jump height, pro agility test time, estimated maximal oxygen uptake (VO₂ max), front plank time and postural stability were measured and compared between groups.

RESULTS

Athletes in the five or more times a week group demonstrated faster pro agility times (5.37 ± 0.43 seconds) than the never group (5.59 ± 0.56 seconds; p = 0.002) and the 1-4 times a week group (5.52 ± 0.47 seconds; p = 0.005). The five or more times a week group demonstrated higher mean vertical jump height (42.9 ± 13.3 vs. 40.3 ± 10.8 cm; p = 0.009) and higher estimated VO₂ max (48.1 vs. 45.6 mL/kg/minute; p = 0.001) than the 1-4 times a week group.

CONCLUSION

Youth athletes who engaged in strenuous physical activity outside of organised sports five or more times a week performed best on functional performance tests.

New guidelines for management of concussion in sport: special concern for youth

The incidence of sports related concussion appears to be increasing, raising alarm over long-term consequences of these head injuries on cognitive function in youth. The American Academy of Neurology (AAN) has recently revised its position statement on concussion in sports, reflecting the burgeoning scientific evidence on its epidemiology, neurophysiology and prognosis. The AAN, along with other scientific organizations addressing concussion policy, has abandoned the use of algorithms for assigning a grade to concussions and instead stresses an individualized approach to concussion management. Recent evidence suggests that children and adolescents may be more susceptible to concussions from head blows, and may take longer to recover, than adults. Young women in certain sports also appear to be more susceptible to concussion than young men. The AAN recommends a more conservative approach to management of sports concussion in children and adolescents. Under no circumstances should a young athlete be allowed to participate in sport while still symptomatic. The use of standardized assessment tools is recommended to aid the healthcare provider in assessing the young athlete's recovery.