Non-specific and ski-specific performance development in peri-pubertal cross-country skiers.

PURPOSE: To evaluate non-specific and ski-specific performance development in male (M) and female (F) peri-pubertal cross-country skiers and to evaluate their relationship with cross-country skiing (XCS) performance and biological maturation within each age category and sex. METHODS: Twenty-one and 19 athletes under 14 and 16 years old, respectively (U14 and U16), were tested for biological maturation; non-specific speed, agility, strength, endurance, and balance; ski-specific speed, agility, and endurance. XCS index was considered as average percentage time-gap from the winner in four official races. Sex and age-category effects were verified and a model predicting XCS index was extrapolated for each group. RESULTS: Performance capacities raised across age categories (p < 0.05) except for non-specific speed, agility, balance, and relative arm strength (p > 0.05). F showed advanced biological maturation and greater balance than M (p < 0.05), while M showed higher performance capacities (p < 0.05). XCS index was not related to biological maturation within each group (p > 0.05); its variance was explained by non-specific speed and ski-specific upper-body endurance in M-U14 (p = 0.014), lower-limb strength and ski-specific agility in M-U16 and F-U14 (both p = 0.001), ski-specific upper-body endurance in F-U16 (p = 0.002). CONCLUSION: Ski-specific performance capacities still develop during peri-puberty, with peri-pubertal M overperforming with respect to F of comparable performance level. XCS index was not influenced by biological maturation withing each age category, but it was rather explained by specific parameters that commonly undergo the "adolescent spurts", accordingly to the average biological maturation level of M and F athletes of each age category.

Are Young Female Basketball Players Adequately Prepared for a Force-Velocity Jumping and Sprinting Assessment?

PURPOSE: The aim of this study was to explore the interday reliability of mechanical variables obtained from the horizontal and vertical force-velocity (FV) profiles in adolescent female basketball players. If found to be reliable, the associations between FV parameters (theoretical maximal force, velocity, and power), squat jump (SJ) height, 30-m sprint, and change of direction (COD) times were evaluated. METHODS: After familiarization, SJ against incremental loads, 30-m sprint, and 505-COD tests were obtained twice in 36 adolescent female basketball players (age = 15.4 [1.2] y). RESULTS: Reliability for vertical FV parameters was unacceptable, whereas 505-COD times and FV horizontal parameters (except for theoretical maximal power) showed a moderate to high reliability. 505-COD time was correlated with FV horizontal parameters (range: r = -.821, -.451), and a large association was observed with both SJ height (r = -.678, -.600) and 30-m sprint time (r = .813, .858). CONCLUSIONS: Due to low levels of strength, our athletes were not adequately prepared to obtain a reliable vertical FV profile. Practitioners can expect acceptable reliability of the horizontal FV profile. Given the association between COD performance and SJ height and 30-m sprint time, we encouraged practitioners with limited equipment at their disposal to use COD and/or 30-m sprint tests.

Quality of lean body mass and jump capacity in high performance young basketball players lean body mass and jump capacity.

The lean body mass (LBM) components have been suggested as important predictors of anaerobic performance, which is highly involved in basketball. We explored with descriptive cross-sectional design the relationship between anaerobic performance and full molecular and cellular body composition profile in young male basketball players. Twenty-one players (age = 16.8 ± 1.6 years; body mass = 76.3 ± 15.7 kg, height = 189.3 ± 12.6 cm) were recruited, 11 elite and 10 local level. Participants were evaluated on multicomponent body composition [LBM, appendicular lean soft tissue (ALST), bone mineral content (BMC), total body water (TBW), intracellular water (ICW) and extracellular water (ECW)] and field-based anaerobic performance (vertical jump, linear sprint, and handgrip strength). The stepwise regression analyses adjusted for confounders showed significant relationships of whole-body and regional body composition components with handgrip and jump performance (P ≤ 0.03). Prediction models combining body composition variables assessed by bioimpedance analysis (BIA) and double-energy X-ray absorptiometry (DXA) revealed that lean mass and hydration ratios (ICW/ECW and ECW/TBW) were strongly associated with jump performance (CMJ and CMJ25kg), independently of the competition level (P < 0.01). The novel finding in this study was that water quality (ICW/ECW) and water distribution (ECW/TBW, ICW) of total and regional LBM were the main predictors of vertical jump capacity in young basketball players.

Repeated Sprint Protocols With Standardized Versus Self-Selected Recovery Periods in Elite Youth Soccer Players: Can They Pace Themselves? A Replication Study.

PURPOSE: Replicating the studies of Gibson et al and Brownstein et al to assess performance, and physiological, and perceived variables during a repeated sprint protocol (RSP) with standardized versus self-selected recovery in youth soccer players. METHODS: Nineteen male soccer players (age 13.1 [1.3] y) completed 2 separate RSPs. RSP1: 10 × 30-m sprints with 30-second recovery and RSP2: 10 × 30-m sprints interspersed with self-selected recovery periods. Mean time of both 10 × 30-m RSPs and self-selected recovery periods of RSP2 were assessed. Heart rate, blood lactate concentration, and rates of perceived exertion were measured following RSPs. RESULTS: RSP2 revealed longer recovery periods (RSP1: 30.0 [0.0] s; RSP2: 39.0 [7.7] s; P < .001; effect size d = 1.648) with shorter repeated sprint time (mean 30-m sprint time: RSP1: 4.965 [0.256] s; RSP2: 4.865 [0.227] s; P = .014; d = 0.414). Blood lactate concentration (P = .002-.005; d = 0.730-0.958), heart rate (P < .001; d = 1.353), and rates of perceived exertion (RSP1: 14.9 [1.9]; RSP2: 12.9 [2.1]; P = .016; d = 1.046) were higher following RSP1. CONCLUSION: In contrast to the original studies, the present replication study demonstrated that self-selected recovery periods during a RSP leads to better repeated sprint performance compared with standardized recovery periods in youth soccer players. The better repeated sprint performance with individual recovery durations in RSP2 was achieved with less physiological and perceived effort.

Widespread Supplement Intake and Use of Poor Quality Information in Elite Adolescent Swiss Athletes.

Compared with adult athletes, rather little is known about supplementation behavior in adolescent athletes. This study's aim was to determine elite adolescent athletes' supplement use and sources of information relating thereto. A total of 430 (87%) of 496 questioned athletes returned the anonymized questionnaire. Thereof, 84% consumed at least one weekly supplement and 97% indicated some supplement intake during the previous 4 weeks. On average, 13.3 supplement servings were consumed per week. The 25th, 50th, and 75th percentile was 4.5, 10.5, and 20.0 servings per week, with a maximum of 67. The most prevalent supplements in use were multimineral products (41% of all athletes), multivitamins (34%), Vitamin C (34%), and Vitamin D (33%). Male athletes consumed significantly more Vitamin C and D, sports drinks, protein powder, and recovery products compared with female athletes; whereas, women consumed more iron supplements. The three most important motives for supplement use were recovery support (40%), health maintenance (39%), and performance enhancement (30%). The most frequent answers to the question "who recommended that you use supplements" were family/friends (36%), a physician (27%), and a trainer/coach (25%). The main three information sources about the supplements in use were the persons who recommended the supplementation (56%), the internet (25%), and information provided by supplement suppliers (11%). A positive doping attitude was associated with the consumption of performance enhancing supplements (p = .017). In conclusion, this study among elite adolescent Swiss athletes indicates a widespread and large-scale use of dietary supplements, which was associated with a low level of information quality.

Does the 2019 Canada's Food Guide meet the needs of young athletes?

Background: The Canada's Food Guide (CFG) encourages Canadians to consume a balanced plate. However, this recommendation may not meet the nutritional needs of young athletes who have increased nutritional requirements. Aim: To evaluate how the 2019 CGF can be used to meet the nutritional needs of young athletes. Method: Five menu scenarios were created using the CFG's balanced plate and recipes from Health Canada. Each menu was analyzed to compare nutrient and energy needs of an index athlete (15-year-old male, 71 kg). Estimated energy requirements were based on nutrition guidelines set by National and International sports-nutrition position statements. Results: The adjusted CFG balanced plate plus an energy dense beverage at every meal was the closest to meeting the index athlete's nutrient requirements. Conclusion: The 2019 CFG's balanced plate needs to be adjusted to meet the nutritional requirements of individuals with active lifestyles.

Validity and repeatability of the Pediatric Allergy Questionnaire for Athletes (AQUAped) for the screening of atopy.

BACKGROUND: High atopy prevalence has been reported in athletes. Having an age-specific questionnaire for predicting atopy is important for an optimal management of young athletes. The study objectives were as follows: (i) developing a scoring system for the Pediatric Allergy Questionnaire for Athletes (AQUAped); (ii) identifying the optimal age target within the range 7-14 years; (iii) assessing AQUAped validity and repeatability in the identified target population. METHODS: A total of 133 young athletes (age 7-14 years) were recruited. Following a screening visit, the participants filled AQUAped at baseline (T0) and after 7 days (T1), concomitantly undergoing skin prick testing. Using atopy as the gold standard (positivity to ≥1 aeroallergen), the 12 core items were scored based on their likelihood ratios, and a total score was calculated. The optimal cut-off was identified based on the Youden's criterion. The repeatability of AQUAped was assessed through the intra-cluster correlation coefficient (ICC). The optimal age target was identified as the largest age range associated with an acceptable cross-validated area under the receiver operating characteristic curve (AUC ≥ 0.70) and an excellent ICC (≥0.75). RESULTS: Forty (30%) children were atopic; the optimal age target was 10-14 years (cross-validated AUC = 0.70, ICC = 0.81). AQUAped total score ranged from -26 to 75, and only 5% of non-atopic children had AQUAped ≥ 24. AQUAped ≥ 2 had 82% specificity, 60% sensitivity, and 74% overall accuracy. CONCLUSION: Developing and testing a scoring system for AQUAped showed that it is a valid and reliable tool for the screening of atopy in young athletes aged 10-14 years.

Menstrual dysfunction and body weight dissatisfaction among Finnish young athletes and non-athletes.

To determine the prevalence of menstrual dysfunction (MD; ie, oligomenorrhea or amenorrhea) and attitudes toward body weight among athletes and non-athletes, we studied a cohort of athletes and non-athletes, in adolescence (14-16 years) and subsequently in young adulthood (18-20 years). We further studied the differences between athletes reporting MD and eumenorrheic athletes at both time periods and identified physical and behavioral characteristics that might predict MD in young adulthood. Data were collected using questionnaires, accelerometers, and a pre-participation screening. In adolescence, the athletes reported current primary amenorrhea more often than the non-athletes (4.7% vs 0%, P = .03). In young adulthood, athletes reported MD more frequently than non-athletes (38.7% vs 5.6%, P < .001). Athletes had less desire than non-athletes to lose weight at both time points, and in adolescence, athletes were more satisfied with their weight. However, about one fifth of the athletes and about 40% of the non-athletes experienced body weight dissatisfaction at both time points. In adolescence, athletes reporting MD had lower BMI than eumenorrheic athletes. In young adulthood, athletes with MD were more physically active than eumenorrheic athletes. The only longitudinal predictor of MD in young adulthood was MD in adolescence. Our findings indicate that MD is relatively frequent among young Finnish athletes. However, athletes appear to have a smaller tendency to experience body weight dissatisfaction than their non-athletic peers. MD seems to track from adolescence to adulthood, suggesting that there is a need to focus on possible causes at the earliest feasible phase of an athlete's career.

Electrocardiographic pattern of apparently healthy African adolescent athletes in Nigeria.

BACKGROUND: Strategies to prevent sudden cardiac death (SCD) among young athletes have become topical worldwide and unrecognized cardiac pathology has been identified as a leading cause. Black ethnicity has been reported as an independent predictor of abnormal electrocardiography (ECG) findings among athletes and the frequency and significance of training-related ECG findings versus findings suggestive of an underlying pathology in the young African athletes is crucial. METHODS: This cross sectional study aimed to determine the prevalence and distribution of ECG patterns in young athletes and controls. A total of 360 participants (180 athletes and 180 controls) were recruited from six secondary schools in Lagos, Nigeria between November 2014 and July 2015. Evaluation included interviewer-administered questionnaires for relevant history, physical examination and resting 12 - lead ECG for each participant. RESULTS: Abnormal ECG patterns were found in 48.3% of athletes and 35.6% of controls. Training-related ECG findings occurred in 33.3% of athletes and 18.3% of controls. Athletes and controls had 7.7% prevalence of training un-related ECG patterns respectively. Left ventricular hypertrophy was the most common ECG finding among the athletes and male athletes had a higher prevalence of ECG abnormalities compared to females. CONCLUSION: Adolescent athletes in Nigeria have a high prevalence of training-related ECG patterns and athletes and non-athletes alike have similar proportions of ECG findings suggestive of underlying structural heart disease. Cardiovascular evaluation including ECG should be performed for young athletes prior to competition at any level and should also be considered as part of pre-school entry assessment for all children.

A comprehensive model of disordered eating among aesthetic athletic girls: Exploring the role of body image-related cognitive fusion and perfectionistic self- presentation.

The incidence of disordered eating among athlete populations is considerably higher than in the general population. Less well understood is the body image-related emotional processes that might lead to disordered eating attitudes and behaviours, specifically among aesthetic athletic girls. Thus, the aim of the present study was to explore the role that body image-related cognitive fusion plays in disordered eating, and the mediating role of body image-related perfectionist self-presentation on this relationship, in aesthetic athletic girls. This study comprised 142 young female athletes from aesthetic sports, who completed self-report measures. A path analysis was conducted to explore the proposed theoretical model, while controlling for age and zBMI. The path model revealed an excellent fit and explained 71% of the severity of disordered eating. Results showed that body image-related cognitive fusion influences disordered eating behaviours, through the mechanism of body image-related perfectionist self-presentation, even when controlling for age and zBMI. Findings suggested that, in aesthetic athletic girls, the entanglement in body image-related thoughts may be associated with the need to present a perfect body image to others, which may lead to disordered eating attitudes and behaviours, adopted as a means to control weight and body shape. The present study highlights the relevance of body image-related processes in disordered eating and suggests the importance of educational programmes that target the development of more adaptive emotion regulation strategies concerning body image in athletes, particularly from aesthetic sports.

Feasibility and diagnostic performance of including point-of-care ultrasound (POCUS) in preparticipation screening of young competitive athletes.

Optimal pre-participative screening in young athletes is still controversial. We sought to evaluate the strategy of including point-of-care ultrasound to electrocardiogram. In total, 1188 young competitive athletes were screened in different sports institutions. This proved to be a useful strategy by improving diagnostic performance primarily with respect to detect structural abnormalities and also by minimising positive false cases of electrocardiogram alone.

Young elite Alpine and Mogul skiers have a higher prevalence of cam morphology than non-athletes.

PURPOSE: To investigate the prevalence of cam morphology in (1) a group of young elite Mogul and Alpine skiers compared with non-athletes and (2) between the sexes. METHOD: The hip joints of 87 subjects [n = 61 young elite skiers (29 females and 32 males) and n = 26 non-athletes (17 females and 9 males)] were examined using MRI, for measurements of the presence of cam morphology (α-angle ≥ 55). RESULTS: The skiers had a significantly higher prevalence of cam morphology compared with the non-athletes (49% vs 19%, p = 0.009). A significant difference (p < 0.001) was also found between females and males, where 22% of the females and 61% of the males had cam morphology. Among the skiers, there was also a significant difference (p < 0.001) between the sexes, where 28% of the females and 68% of the males had cam morphology. This difference between the sexes was not found in the non-athletic group. No significant differences were found between Mogul and Alpine skiers. CONCLUSION: Young male elite skiers have a higher prevalence of cam morphology of the hips compared with non-athletes. LEVEL OF EVIDENCE: II.

UV protection for young athletes: using participatory program planning to develop a sports schools program.

BACKGROUND: The incidence of melanoma increased rapidly throughout the last decades, with overexposure to ultraviolet (UV) radiation being an established risk factor. Due to their intensive sun exposure, many student athletes (SAs) have an increased risk for skin cancer. The Clever in Sun and Shade Program (CSSP) aims at enforcing positive attitudes toward UV protection (UVP) and at supporting sports schools in establishing UVP strategies. METHODS: CSSP was developed in 2019 using participatory program planning (PPP) as well as following WHO recommendations for UVP at schools. After drafting first material, within a PPP groups were conducted at a partner school (convenience sample 1) with students (n = 20), teachers (n = 5), school administration (n = 2), and coaches (n = 5). Materials were then adapted. Program acceptance and feasibility were tested at two further schools (convenience sample 2) with PPP groups of students (n = 95) and school administration (n = 2). Content analyses and descriptive statistics were conducted. RESULTS: Less than 50% of SAs and coaches of sample 1 expressed positive attitudes toward UVP, less than 10% reported appropriate UVP behavior. By using PPP, program material was adapted to the target groups' needs, i.e., by including specific barriers and solutions. Only the most accepted video drafts were produced. The majority of SAs of sample 2 (80-86%) used predominantly positive adjectives such as "important" and "positive" to describe the completed videos and the behavior self-check poster. CONCLUSIONS: PPP process has greatly influenced concept and materials of CSSP for sports schools. Integration of future program participants has proven to be an important component in creating a fitting and feasible program. CSSP for sports schools is a program free of charge that enables sports schools to integrate UVP into their daily routine. It will be disseminated in cooperation with German Olympic Sports Confederation and German Cancer Aid in 2021.

How Length Sizes Affect Body Composition Estimation in Adolescent Athletes Using Bioelectrical Impedance.

Bioelectrical impedance analysis (BIA) is a common practice to assess body composition in athletes, however, when measuring athletes with specific body geometry, its accuracy may decrease. In this study we examined how length dimensions affect body composition estimation and we compared BIA and dual-energy X-ray absorptiometry (DXA) assessments in three sports. 738 male adolescent athletes (15.8 ± 1.4 years) from three sports (soccer, basketball, and handball) were measured. Body composition was estimated by BIA (InBody 720) and by DXA (Lunar Prodigy). Differences between the two methods were tested by Bland-Altman analysis and by paired t-test. ANOVA was used for inter-group comparisons. Pearson correlation and multivariate linear regression was used to look for the relationship between segmental lean body mass and length dimensions. BIAInBody 720 consistently underestimated percent body fat (PBF) and overestimated lean body mass (LBM) than DXA. The magnitude of the differences between the two methods varied among the examined sports. Handball (PBF = 8.3 ± 2.4 %; LBM = -5.0 ± 2.1 kg) and basketball players (PBF = 8.8 ± 2.3 %; LBM = -5.3 ± 1.8 kg) had significantly larger differences between the two methods than soccer players (PBF = 6.4 ± 2.2 %; LBM = -3.1 ± 1.4 kg). There was a negative correlation between differences in segmental LBM estimation and length sizes (trunk length, upper extremity length, lower extremity length). The highest correlation was found for lower extremity (r = -0.4). Longer lower extremity resulted in greater difference in LBM estimation. The differences between the sport disciplines are most probably attributed to body height differences. Length dimensions result in overestimation of LBM with BIA, thus body composition assessment with BIAInBody 720 needs to be carefully interpreted in athletes with extreme length sizes, especially, with basketball players.

Knee pain is associated with lower back pain in young baseball players: a cross-sectional study.

PURPOSE: Considerable research has focused on shoulder and elbow injuries among baseball players; however, although lumbar spine and knee injuries are commonly experienced, they are less frequently studied. During common motions in baseball, such as throwing, hitting, and running, energy is transferred from the lower extremities through the lower back to the upper body. Lower extremity pain, as well as lower back pain (LBP), can disrupt the kinematic chain, and it is important to understand the association between lower extremity complaints and LBP. The purpose of this study was to elucidate the association between knee pain and LBP among young baseball players. METHODS: A cross-sectional study was conducted with young baseball players (aged 6-15 years, n = 1,609) using a self-reported questionnaire. Multivariate logistic regression models were used for analyses. Variables considered in the models were sex, age, body mass index, team levels, number of days of training per week, number of hours in practice per day on weekdays and weekend, frequency of participation in games, practice intensity, and player position. RESULTS: The point prevalence of LBP and knee pain was 8.4% and 13.1%, respectively. Knee pain was significantly associated with LBP. Using the absence of knee pain as a reference, the adjusted odds ratio (95% confidence interval) for LBP was 5.83 (3.93-8.65) (p < 0.001) in the presence of knee pain. CONCLUSIONS: Knee pain was associated with LBP among young baseball players. Clinicians should pay attention to knee complaints to prevent and treat LBP among young baseball players. LEVEL OF EVIDENCE: III.

High incidence of posterior glenoid dysplasia of the shoulder in young baseball players.

BACKGROUND: Rounding of the posterior glenoid rim is observed in young throwing athletes with internal shoulder impingement and is considered developmental dysplasia of the glenoid. The aim of our study was to determine the incidence rate of dysplastic changes of the glenoid within a group of 92 young baseball players. METHODS: The study group included 92 male baseball players, with a mean age of 14.63 years. Of these patients, 30 were diagnosed with Little Leaguer's shoulder and 62 with a painful baseball-throwing shoulder with no abnormal findings on x-ray. The posterior glenoid rim of the affected shoulder was compared with the contralateral nonpainful shoulder, with the 2 following outcomes measured on radiographs obtained using the modified Bernageau imaging method: the distance between the anterior and posterior glenoid rims and the presence or absence of dysplasia of the posterior glenoid rim. RESULTS: The mean distance between the anterior and posterior glenoid rims was significantly shorter in the painful shoulders (mean, 26 mm) than in the nonpainful shoulders (mean, 29 mm; P < .0001). Dysplasia of the posterior glenoid rim was identified in 89 painful shoulders (96.7%), with 9 cases (9.7%) identified on the unaffected contralateral side (P < .001). The presence of dysplasia was not correlated with the age at which baseball playing began. CONCLUSION: The incidence of dysplasia of the posterior glenoid rim is high (96.7%) among young baseball players with a painful shoulder. The identified dysplasia may be related to impaired development of the inferior peripheral secondary glenoid ossification center due to repetitive throwing.

The Relationship between Moral Climate of Sports and the Moral Behavior of Young Athletes: A Multilevel Meta-analysis.

Sports are among the most important leisure activities for youth and adolescents. Both positive (i.e., prosocial) and negative (i.e., antisocial) moral behaviors occur on the playing field. To stimulate positive sports experiences, it is important to understand which factors are related to the moral behavior of young athletes; one of these is the moral climate, that is, the socio-moral environment in which sports take place. Little is known about the overall strength of the relationship between moral climate and moral behavior of young athletes, as well as the potential moderating factors of this relationship. A meta-analysis of 27 studies containing 117 effect sizes and N = 7726 young athletes (age < 18 years) was conducted. The results show that there is an overall significant association between these two variables (r= 0.40), indicating that a prosocial moral climate is related to less antisocial and more prosocial behavior, while an antisocial moral climate is associated with more antisocial and less prosocial behavior of young athletes. Two study characteristics significantly moderated this relationship: specifically, stronger associations were found in cross-sectional and in older studies. In addition, the strength of the association between moral climate and moral behavior was stronger for antisocial moral climate compared to prosocial moral climate. Finally, associations for team members were stronger than those of coaches or a broad moral club climate. Implications for further research and sports practice are discussed.

The Effects of Plyometric Jump Training on Jumping and Swimming Performances in Prepubertal Male Swimmers.

Swimming performance can be improved not only by in-water sport-specific training but also by means of dry land-training (e.g., plyometric jump training [PJT]). This study examined the effects of an 8-week PJT on proxies of muscle power and swimming performance in prepubertal male swimmers. Participants were randomly allocated to a PJT group (PJT; n = 14; age: 10.3 ± 0.4 years, maturity-offset = -3±0.3) or a control group (CG; n = 12; age: 10.5 ± 0.4 years, maturity-offset = -2.8 ± 0.3). Swimmers in PJT and CG performed 6 training sessions per week. Each training session lasted between 80 and 90 minutes. Over the 8 weeks in-season training period, PJT performed two PJT sessions per week, each lasting between 25 to 30 minutes (~1 hour per week) in replacement of sport-specific swimming drills. During that time, CG followed their regular sport-specific swimming training (e.g., coordination, breathing, improving swimming strokes). Overall training volume was similar between groups. Pre- and post-training, tests were conducted to assess proxies of muscle power (countermovement-jump [CMJ]), standing-long-jump [SLJ]) and sport-specific swimming performances (15-, 25-, and 50-m front-crawl, 25-m kick without push [25-m kick WP], and 25-m front-crawl WP). No training or test-related injuries were detected over the course of the study. Between-group analyses derived from magnitude-based inferences showed trivial-to-large effects in favour of PJT for all tests (ES = 0.28 to 1.43). Within-group analyses for the PJT showed small performance improvements for CMJ (effect-size [ES] = 0.53), 25-m kick WP (ES = 0.25), and 50-m front crawl (ES = 0.56) tests. Moderate performance improvements were observed for the SLJ, 25-m front-crawl WP, 15-m and 25-m front-crawl tests (ES = 0.95, 0.60, 0.99, and 0.85, respectively). For CG, the within-group results showed trivial performance declines for the CMJ (ES=-0.13) and the 50-m front-crawl test (ES = -0.04). In addition, trivial-to-small performance improvements were observed for the SLJ (ES = 0.09), 25-m kick WP (ES = 0.02), 25-m front-crawl WP (ES = 0.19), 25-m front-crawl (ES = 0.2), (SLJ [ES = 0.09, and 15-m front crawl (ES = 0.36). Short-term in-season PJT, integrated into the regular swimming training, was more effective than regular swimming training alone in improving jump and sport-specific swimming performances in prepubertal male swimmers.

Anxiety and burnout in young athletes: The mediating role of cognitive appraisal.

This study tested the relationship between trait anxiety, cognitive appraisal, and athletes' burnout proposing two hypotheses: (a) there is a direct relationship between athletes' trait anxiety and cognitive appraisal and burnout, and (b) cognitive appraisal mediates the relationship between trait anxiety and burnout, and this mediation occurs despite the competitive level and sport records of athletes. The study included 673 young athletes and provided measures of trait anxiety, cognitive appraisal, and burnout. Structural equation modeling indicated that cognitive appraisal mediates the relationship between trait anxiety and burnout, confirming hypothesis 2, and this model provided better fit than the direct model of hypothesis 1. However, the mediation also indicated that the direct relationship between trait anxiety and burnout should be considered. The mediating model was invariant according to competitive levels and sport records. In conclusion, cognitive appraisal is an important variable in explaining athletes' burnout.

Back pain prevalence in adolescent athletes.

The research aimed to investigate back pain (BP) prevalence in a large cohort of young athletes with respect to age, gender, and sport discipline. BP (within the last 7 days) was assessed with a face scale (face 1-2 = no pain; face 3-5 = pain) in 2116 athletes (m/f 61%/39%; 13.3 ± 1.7 years; 163.0 ± 11.8 cm; 52.6 ± 13.9 kg; 4.9 ± 2.7 training years; 8.4 ± 5.7 training h/week). Four different sports categories were devised (a: combat sports, b: game sports; c: explosive strength sport; d: endurance sport). Analysis was described descriptively, regarding age, gender, and sport. In addition, 95% confidence intervals (CI) were calculated. About 168 (8%) athletes were allocated into the BP group. About 9% of females and 7% of males reported BP. Athletes, 11-13 years, showed a prevalence of 2-4%; while prevalence increased to 12-20% in 14- to 17-year olds. Considering sport discipline, prevalence ranged from 3% (soccer) to 14% (canoeing). Prevalences in weight lifting, judo, wrestling, rowing, and shooting were ≥10%; in boxing, soccer, handball, cycling, and horse riding, ≤6%. 95% CI ranged between 0.08-0.11. BP exists in adolescent athletes, but is uncommon and shows no gender differences. A prevalence increase after age 14 is obvious. Differentiated prevention programs in daily training routines might address sport discipline-specific BP prevalence.