Muscular strength training impacts in young athletes / Impactos do treinamento de força muscular em jovens atletas / Impactos del entrenamiento de la fuerza muscular en jóvenes atletas

ABSTRACT Introduction: Muscle strength is directly related to its cross-sectional area and the volume of its fibers, but there is no absolute linear relationship between hypertrophy and improvement in athletic performance. Under this complex perspective, muscle training strategies have been implemented to promote relevant muscle strength and improve overall athletic ability. Objective: Explore the impacts of muscle strength training on young athletes based on sport kinetic principles. Methods: we adopted the method of intragroup statistical comparison with body indexes of 10 volunteers undergoing muscle training focused on the core and lower limb set. Results: Muscle strength gain was effectively verified via electromyogram, and the test of athletic skills showed an evolution in jumping, balance, and reduction of wrong passes. Conclusion: Evidence-based muscle training can increase muscle strength and promote sports skill gain in young athletes. Level of evidence II; Therapeutic studies - investigation of treatment results.

RESUMO Introdução: A força muscular está ligada diretamente à área de sua seção transversal e ao volume de suas fibras, porém não há relação linear absoluta entre hipertrofia e melhora no desempenho atlético. Sob essa complexa perspectiva, estratégias de treinamento muscular vêm sendo implementadas para promover a força muscular relevante, no intuito de promover a melhora da capacidade atlética geral. Objetivo: Explorar os impactos do treinamento de força muscular nos jovens atletas baseado nos princípios cinéticos do esporte. Métodos: adotou-se o método de comparação estatística intragrupo com índices corporais de 10 voluntários submetidos ao treinamento muscular focado no conjunto do core e membros inferiores. Resultados: O ganho de força muscular foi efetivamente constatado via eletromiograma e o teste das habilidades atléticas demonstrou uma evolução no salto, equilíbrio e redução de passes errados. Conclusão: O treinamento muscular baseado em evidências consegue aumentar a força muscular e promover o ganho de habilidade esportiva nos jovens atletas. Nível de evidência II; Estudos terapêuticos - investigação dos resultados do tratamento.

RESUMEN Introducción: La fuerza muscular está directamente relacionada con su área transversal y con el volumen de sus fibras, pero no existe una relación lineal absoluta entre la hipertrofia y la mejora del rendimiento deportivo. Bajo esta compleja perspectiva, se han implementado estrategias de entrenamiento muscular para promover la fuerza muscular pertinente, con el fin de promover la mejora de la capacidad atlética general. Objetivo: Explorar los impactos del entrenamiento de la fuerza muscular en jóvenes atletas basándose en los principios de la cinética deportiva. Métodos: se adoptó el método de comparación estadística intragrupo con los índices corporales de 10 voluntarios sometidos a un entrenamiento muscular centrado en todo el núcleo y las extremidades inferiores. Resultados: La ganancia de fuerza muscular se verificó eficazmente a través del electromiograma y la prueba de habilidades atléticas mostró una evolución en los saltos, el equilibrio y la reducción de los pases erróneos. Conclusión: El entrenamiento muscular basado en la evidencia puede aumentar la fuerza muscular y promover la ganancia de habilidades deportivas en los atletas jóvenes. Nivel de evidencia II; Estudios terapéuticos - investigación de los resultados del tratamiento.

Promoting the Participation of Children and Adolescents With Disabilities in Sports, Recreation, and Physical Activity.

The benefits of physical activity are likely universal for all children, including children and adolescents with disabilities (CWD). The participation of CWD in physical activity, including adaptive or therapeutic sports and recreation, promotes inclusion, minimizes deconditioning, optimizes physical functioning, improves mental health as well as academic achievement, and enhances overall well-being. Despite these benefits, CWD face barriers to participation and have lower levels of fitness, reduced rates of participation, and a higher prevalence of overweight and obesity compared with typically developing peers. Pediatricians and caregivers may overestimate the risks or overlook the benefits of physical activity in CWD, which further limits participation. Preparticipation evaluations often include assessment of health status, functional capacity, individual activity preferences, availability of appropriate programs, and safety precautions. Given the complexity, the preparticipation evaluation for CWD may not occur in the context of a single office visit but rather over a period of time with input from the child's multidisciplinary team (physicians, coaches, physical education teachers, school nurses, adaptive recreation specialists, physical and occupational therapists, and others). Some CWD may desire to participate in organized sports to experience the challenge of competition, and others may prefer recreational activities for enjoyment. To reach the goal of inclusion in appropriate physical activities for all children with disabilities, child, family, financial, and societal barriers to participation need to be identified and addressed. Health care providers can facilitate participation by encouraging physical activity among CWD and their families during visits. Health care providers can create "physical activity prescriptions" for CWD on the basis of the child's preferred activities, functional status, need for adaptation of the activity and the recreational opportunities available in the community. This clinical report discusses the importance of participation in sports, recreation, and physical activity for CWD and offers practical suggestions to health care providers.

The Impact of a Short-term Intervention on Adolescent Eating Habits and Nutritional Knowledge.

BACKGROUND: Adequate dietary habits and physical activity during childhood and adolescence may promote growth and cognitive development and contribute to the prevention of chronic disease in later life. School is considered an important social environment that can promote healthy eating habits and life-style changes. OBJECTIVES: To evaluate the effects of a school-based intervention on nutritional knowledge, eating habits, and physical activity of adolescents. METHODS: We conducted a prospective questionnaire-based study. Anonymous questionnaires were administered at the beginning of the academic year (September 2014) in one high school. During the following year, vending machines containing milk products were installed within the school facility, and students were given two informative nutrition lectures regarding proper nutrition for age, calcium requirement and importance, and physical activity. One active sports day was initiated. At the beginning of the following academic year (September 2015), the students completed the same questionnaires. RESULTS: The study was comprised of 330 teenagers, mean age 15.1 ± 1.39 years, 53% males. Response rate was 83.6% ± 0.4% to multiple choice questions, 60.7% ± 0.5% to multiple section tables, and 80.3% ± 0.9% to open questions. Post-intervention, respondents reported an increase in eating breakfast (57% vs. 47.5%, P = 0.02) and a decrease in purchasing food at school (61.6% vs. 54.3%, P = 0.03). No changes were observed in consumption of milk products, knowledge regarding calcium and vegetable consumption, or sports activities. CONCLUSIONS: Short-term high school-based interventions may lead to improvements in eating habits but are not sufficient for changing nutritional knowledge and physical activity.

Participation in sport in childhood and adolescence: Implications for adult fitness.

OBJECTIVES: To investigate whether participation in sport during the developmental stages of life is associated with cardiorespiratory fitness (CRF) in adulthood. DESIGN: Observational longitudinal study. METHODS: Participants were Generation 2 of the Raine Study. Questionnaires related to participation in sport were administered at ages 5, 8, 10, 14 and 17 years. These data were used to develop sex-specific trajectories of sports participation: (for males) Consistent Participators, Drop-Outs and Joiners; and (females) Consistent Participators, Non-Participators and Drop-Outs. At age 28.3 ±â€¯0.6 years, participants completed a graded maximal exercise test (i.e. V̇O2peak test). A General Linear Model assessed differences in CRF between trajectories. RESULTS: 402 participants n = 231 (57.5%) male, n = 171 (42.5%) female were included in the study. In males, Consistent Participators (all p < 0.001) and Joiners (p < 0.050) had greater fitness than Drop-Outs. In females, Consistent Participators had greater fitness than Non-Participators (p < 0.050), but there were no significant differences in fitness between Consistent Participators and Drop-Outs (p > 0.050) or Non-Participators and Drop-Outs (p > 0.050). CONCLUSION: Participation in sport during childhood and adolescence is associated with greater fitness in adulthood, compared to individuals who never participate or those that cease participation in adolescence. A simple dichotomous question regarding sports participation over the childhood and adolescent period can be implemented to predict better fitness outcomes in young adulthood. Childhood and adolescence could be an opportune stage in life for parents, schools and governments to facilitate participation in sport and prevent drop out, as it may have an impact on long term risk reduction, with associated health and economic benefits.

Association between sleep quality and pain in young amateur athletes / Asociación entre calidad del sueño y dolor en jóvenes atletas amateurs / Associação entre qualidade do sono e dor em jovens atletas amadores

ABSTRACT Introduction: It has been shown that there is a close association between sleep quality and pain. In young athletes, sleep disorders and pain have a particularly high prevalence; however, the relationship between them has not been widely studied. Objective: To study the association between sleep quality and pain in young athletes. Methods: A cross-sectional study was conducted in which 71 young amateur athletes (39 males) were included. The mean age was 16.9 ± 1.2 years, with 6.5 ± 3.2 years of sports practice and 5.2 ± 1.2 hours of training per week. Sleep quality was evaluated using the Pittsburgh Sleep Quality Index (PSQI). The participants were classified according to sleep quality, as PSQI-I = without sleep disorders, PSQI-II = requiring medical assistance and PSQI-III = requiring medical assistance and treatment. Also, pain intensity was assessed on the Numerical Rating Scale, both at rest (NRSr) and during sports activity (NRSs), along with pain duration. Results: The individuals classified as PSQI-III presented higher NRSr (Mdn = 2.0; IQR = 4.0 vs. Mdn = 0.0; IQR = 2.0; p = 0.04) and higher NRSs (Mdn = 4.0; IQR = 5.0 vs. Mdn = 0.0; IQR = 2.0; p = 0.03) than the individuals classified as PSQI-I. No differences were observed in relation to pain duration. The PSQI score was positively but weakly associated with NRSr (rs = 0.24, p=0.046) and NRSs (rs = 0.27, p = 0.03) but not with pain duration. Conclusion: Young athletes with lower levels of sleep quality show higher levels of pain at rest and during sports practice. Therefore, sleep quality and pain should be considered in the routine assessment of young athletes, by technical and health teams. Level of evidence III; type of study: Cross-sectional .

RESUMEN Introducción: Se demostró que existe estrecha relación entre calidad del sueño y dolor. En atletas jóvenes, los disturbios del sueño y dolor tienen prevalencia bastante alta, sin embargo, la relación entre ellos no fue ampliamente estudiada. Objetivo: Estudiar la asociación entre calidad del sueño y dolor en atletas jóvenes. Métodos: Fue realizado un estudio transversal, en el cual fueron incluidos 71 atletas jóvenes amateurs (39 hombres). El promedio de edad fue de 16,9 ± 1,2 años, con 6,5 ± 3,2 años de práctica deportiva y 5,2 ± 1,2 horas de entrenamiento por semana. La calidad del sueño fue evaluada por medio del Índice de Calidad del Sueño de Pittsburgh (PSQI). Los participantes fueron clasificados de acuerdo con la calidad del sueño, PSQI-I= sin disturbios del sueño, PSQI-II= requiere atención médica y PSQI-III= requiere atención médica y tratamiento. Además, la intensidad del dolor fue evaluada en la Escala de Evaluación Numérica en reposo (EANr) y durante la actividad deportiva (EANe), juntamente con la duración del dolor. Resultados: Los individuos clasificados como PSQI-III presentaron mayor valor en el EANr (Mdn = 2,0; IQR = 4,0 vs. Mdn = 0,0; IQR = 2,0; p = 0,04) y EANe mayores (Mdn = 4,0; IQR = 5,0 vs. Mdn = 0,0; IQR = 2,0; p = 0,03) que los individuos clasificados con PSQI-I. No fue observada ninguna diferencia con relación a la duración del dolor. El puntaje del PSQI fue positivo y con débil asociación a EANr (rs = 0,24, p=0.046) y EANe (rs = 0,27, p = 0,03), pero no con la duración del dolor. Conclusión: Los atletas jóvenes con niveles más bajos de calidad del sueño tienen niveles más elevados de dolor en reposo y durante la práctica deportiva. Por lo tanto, la calidad del sueño y el dolor deben ser considerados por los equipos técnicos y de salud en la evaluación rutinaria de atletas jóvenes. Nivel de evidencia III;Tipo de estudio: Transversal.

RESUMO Introdução: Demonstrou-se que existe estreita associação entre qualidade do sono e dor. Em atletas jovens, distúrbios do sono e dor têm prevalência bastante alta, no entanto, a relação entre eles não foi amplamente estudada. Objetivo: Estudar a associação entre qualidade do sono e dor em atletas jovens. Métodos: Foi realizado um estudo transversal, no qual foram incluídos 71 atletas jovens amadores (39 homens). A média de idade foi de 16,9 ± 1,2 anos, com 6,5 ± 3,2 anos de prática esportiva e 5,2 ± 1,2 horas de treinamento por semana. A qualidade do sono foi avaliada por meio do Índice de Qualidade do Sono de Pittsburgh (PSQI). Os participantes foram classificados de acordo com a qualidade do sono, PSQI-I = sem distúrbios do sono, PSQI-II = requer atendimento médico e PSQI-III = requer atendimento médico e tratamento. Além disso, intensidade da dor foi avaliada na Escala de Avaliação Numérica em repouso (EANr) e durante a atividade esportiva (EANe), juntamente com a duração da dor. Resultados: Os indivíduos classificados como PSQI-III apresentaram maior valor no EANr (Mdn = 2,0; IQR = 4,0 vs. Mdn = 0,0; IQR = 2,0; p = 0,04) e EANe maiores (Mdn = 4,0; IQR = 5,0 vs. Mdn = 0,0; IQR = 2,0; p = 0,03) do que os indivíduos classificados com PSQI-I. Nenhuma diferença foi observada com relação à duração da dor. O escore do PSQI foi positivo e com fraca associação a EANr (rs= 0,24, p=0.046) e EANe (rs= 0,27, p = 0,03), mas não com a duração da dor. Conclusão: Atletas jovens com níveis mais baixos de qualidade do sono têm níveis mais elevados de dor em repouso e durante a prática esportiva. Portanto, a qualidade do sono e a dor devem ser consideradas pelas equipes técnicas e de saúde na avaliação rotineira de atletas jovens. Nível de evidência III; Tipo de estudo: Transversal.

Subconcussive Head Impacts and Neurocognitive Function Over 3 Seasons of Youth Football.

OBJECTIVE: To determine the association between repetitive subconcussive head impacts and neurobehavioral outcomes in youth tackle football players. METHODS: Using helmet-based sensors, we measured head impacts for 3 consecutive seasons of play in 29 male players age 9-11. Cumulative impact g's were calculated. Players completed a battery of outcome measures before and after each season, including neuropsychological testing, vestibular-ocular sensitivity, and self- and parent-reported measures of symptoms and attention-deficit hyperactivity disorder (ADHD). RESULTS: Average cumulative impact over 3 seasons was 13 900g. High-intensity hits predicted worse change for self-reported social adjustment (P = .001). Cumulative impact did not predict change in any of the outcome measures. History of ADHD, anxiety, and depression predicted worse change for self-reported symptoms and social adjustment, independent of head impacts. When players were stratified into 3 groups based on cumulative impact across all 3 seasons, differences in outcome measures existed prior to the start of the first season. These differences did not further increase over the course of the 3 seasons. CONCLUSION: Over 3 consecutive seasons of youth tackle football, we found no association between cumulative head impacts and neurobehavioral outcomes. Larger sample sizes and longer follow-up times would further assist in characterizing this relationship.

Injuries in youth football and the relationship to player maturation: An analysis of time-loss injuries during four seasons in an English elite male football academy.

A better insight into injuries in elite-youth football may inform prevention strategies. The purpose of this prospective cohort study was to investigate the frequency, incidence, and pattern of time-loss injuries in an elite male football academy, exploring injuries in relation to age and maturation status. Across four consecutive playing seasons, playing exposure and injuries to all academy players (U'9 to U'21) were recorded by club medical staff. Maturation status at the time of injury was also calculated for players competing in U'13 to U'16 aged squads. Time-loss injury occurrence and maturation status at time of injury were the main outcome measures. A total of 603 time-loss injuries were recorded, from 190 different players. Playing exposure was 229 317 hours resulting in an overall injury rate of 2.4 p/1000 h, ranging from 0.7 p/1000 h (U'11) to 4.8 p/1000 h (U'21). Most injuries were traumatic in mechanism (73%). The most common injury location was the thigh (23%), and the most common injury type was muscle injury (29%) combining to provide the most common injury diagnosis; thigh muscle injury (17%). In U'13-U'16 players, a higher number of injuries to early-maturing players were observed in U'13-U'14 players, while more injuries to U'15-U'16 players occurred when classed as "on-time" in maturity status. Maturation status did not statistically relate to injury pattern; however, knee bone (not-fracture) injuries peaked in U'13 players while hip/groin muscle injuries peaked in U'15 players.

Short and long versions of a 12-week netball specific neuromuscular warm-up improves landing technique in youth netballers.

OBJECTIVE: To investigate the efficacy of two 'NetballSmart', netball specific warm-ups in improving landing technique measures in New Zealand secondary school netball players. DESIGN: Multi-site cluster experimental trial. PARTICIPANTS: 77 youth participants, mean ± SD age = 15.8 ± 0.9 were recruited from secondary school netball teams. SETTING: 12 teams from 6 schools performed either the NetballSmart Dynamic Warm-up (NSDW) (n = 37); or Power warm-up (PWU) (n = 40), three times a week for 12 weeks. All players within a school (2 teams) were assigned the same warm-up, avoiding treatment contamination. MAIN OUTCOME MEASURES: A series of unilateral and bilateral drop vertical jumps on to a portable force plate were completed by all participants. Measures included peak vertical ground reaction force (GRF) for single-leg and bilateral landings; frontal plane projection angle (FPPA) for right and left single-leg landings and Landing error scoring system (LESS) for bilateral landings. Paired t-tests were used to assess mean differences pre and post the warm-up. Generalised linear mixed effects models were developed to evaluate the effects between the NSDW and PWU groups. RESULTS: Significant improvements were found in all the landing technique outcome measures for both warm-up groups (ES Range- GRF = -0.6 to -1.1; FPPA = 0.8 to 1.2; LESS = -1.6 to-3.2; p < 0.05). Results of mixed effects models revealed that there was only a significantly greater improvement in LESS for the PWU group (ß = -0.30, p = 0.001). CONCLUSION: Results show both warm-ups can improve landing technique measures in youth secondary school netball players. It is recommended that coaches should consider implementing one of the two warm-ups in their netball programmes. Their choice of warm-up will likely be dependent on their environment and time demands.

High Thoracic Kyphosis and Backward Trunk Inclination Angles in the Single-Leg Standing Position Associate With Medial Elbow Injuries in Youth Baseball Players: A Cross-Sectional Study.

CONTEXT: Baseball pitching is a coordinated movement involving the spine. A previous study indicated that increased thoracic kyphosis angle in a standing position was a risk factor for medial elbow injuries in youth baseball players. However, spinal alignments in single-leg standing and their relationships with medial elbow injuries, scapular alignment, or hip joint range of motion are unclear. OBJECTIVE: To examine the difference in spinal alignment between standing and single-leg standing positions in youth baseball players and analyze their relationship with elbow injuries, scapular alignment, or hip joint range of motion. DESIGN: Cross-sectional study. SETTING: University laboratory. PARTICIPANTS: There were 51 youth baseball players with medial epicondylar fragmentation (medial elbow injury group) and 102 healthy youth baseball players (control group). MAIN OUTCOME MEASURES: Thoracic kyphosis, lumbar lordosis, and trunk inclination angles during standing and single-leg standing, forward scapular posture, and hip joint range of motion. RESULTS: In the single-leg standing position, the thoracic kyphosis and backward trunk inclination angles were significantly higher in the medial elbow injury group than in the control group (P = .016 and P = .046, respectively). In the standing position, no significant difference was observed between both groups. The thoracic kyphosis angle in single-leg standing was positively correlated with the bilateral forward scapular posture in the medial elbow injury (P = .008 and P < .001 on the throwing and nonthrowing sides, respectively) and control (P = .010 and P = .032 on the throwing and nonthrowing sides, respectively) groups. CONCLUSIONS: High thoracic kyphosis and backward trunk inclination angles are characteristics during single-leg standing in youth baseball players with medial elbow injuries. Spinal alignment measurement in single-leg standing may be useful for identifying youth baseball players who are at risk for sustaining medial elbow injury.

Bilateral difference between lower limbs in children practicing laterally dominant vs. non-laterally dominant sports.

Bilateral asymmetry in lower-limb power and dynamic balance has been associated with increased risk of sport injury, whereas there is a lack of research examining this asymmetry for child athletes. Twenty-eight fencers (19 boys and 9 girls, aged 9.71 ± 1.08 years) and 28 Taekwondo athletes (19 boys and 9 girls, aged 9.71 ± 1.08 years) were examined on the single-leg jump and Star Excursion Balance Test (SEBT) performance. A mixed model design ANOVA (2 [Sex: Boys, Girls] × 2 [Sport group: Fencing, Taekwondo] × 2 [Limb: Dominant, Non-dominant Leg]) was conducted to examine for difference for each test. There was a significant main effect of limb on hop and triple hop distance (p < 0.05). A significant limb by sex interaction (p = 0.000) was shown for the single-leg countermovement jump (CMJ) performance, wherein a bilateral difference was only shown in boys. In SEBT, a main effect (p = 0.007) of limb was identified for posterolateral (PL) reach distance. A limb by sex interaction (p = 0.009) was also shown for posteromedial (PM) reach distance, wherein a bilateral difference was only shown in girls. These findings suggest that child athletes in both laterally dominant and non-laterally dominant sports showed inter-limb asymmetry of leg power and dynamic balance. Sex should be an important consideration when evaluating bilateral difference of leg power and dynamic balance for child athletes.

Effect of Plyometric Training on Sport Performance in Adolescent Overhead Athletes: A Systematic Review.

CONTEXT: Plyometric training has been shown to be beneficial in adolescent overhead athletes. However, existing research on the effects of plyometrics on sport performance has been limited. OBJECTIVE: To systematically review the current literature to investigate whether plyometric training intervention improves upper- and lower-body sport performance. DATA SOURCES: Two electronic databases (MEDLINE and Web of Science) were searched using specific Medical Subject Headings (MeSH) terms up to February 2019, and hand-searching was performed by looking to relevant studies that were cited in other studies. STUDY SELECTION: A total of 932 items were identified and were further assessed for the eligibility in the systematic review. For a study to be eligible, each of the following inclusion criteria had to be met: (1) participants were aged 13 to 18 years and selected from a sports or athletic population and the study (2) involved the evaluation of a plyometric training intervention with an aim to improve sports performance; (3) must have included a control intervention and/or control group; (4) included a quantitative objective measure of sport performance variables concerning throwing, jumping, running, and sprinting; and (5) was published in English. STUDY DESIGN: Systematic review. LEVEL OF EVIDENCE: Level 3. DATA EXTRACTION: A first screening was conducted based on title and abstract of the articles. In the second screening, the full text of the remaining articles was evaluated for the fulfillment of the inclusion criteria. RESULTS: A total of 14 studies were included in this review. The methodological quality of the included studies ranged from low to moderate. There is moderate evidence that plyometric training intervention improves throwing and jumping performances. There is also preliminary evidence that plyometric training intervention improves sprint performance. CONCLUSION: The current evidence suggests that sport performance consisting of throwing capacity, jumping ability, and sprint performance significantly improved due to plyometric training interventions in adolescent overhead athletes.

Decreased Physical Activity and Sleep, Not Sport Specialization, Predict Illness in Middle School Athletes.

BACKGROUND: The relationships between sport specialization, physical activity, sleep, and illness in younger athletes are unknown. Therefore, the purpose of this study was to evaluate the independent effects of sport specialization, sleep, and physical activity on illness in middle school athletes. HYPOTHESIS: Decreased sleep, decreased physical activity, and higher levels of sport specialization will be associated with an increased risk of illness among middle school athletes. STUDY DESIGN: Prospective cohort study. LEVEL OF EVIDENCE: Level 4. METHODS: Parents of middle school-aged children reported baseline sport specialization (low, moderate, or high) as well as sleep duration, physical activity, and illnesses every week throughout the academic year. A mixed-effects logistic regression model was used to assess the association between illness and specialization while accounting for sleep and physical activity for the prior week as fixed effects and each individual as a random effect. RESULTS: A total of 233 children (mean age, 12.1 ± 1.2 years; 61% male) participated, of whom 41%, 25%, and 34% were categorized as low, moderate, and high specialization, respectively. The proportion of individuals who experienced illness did not differ by specialization level (low, 76%; moderate, 70%; high, 59%; P = 0.064). In the multivariable model, the odds of illness compared with the low specialization group was not significantly different for moderate (odds ratio [OR], 0.93; 95% CI, 0.70-1.23; P = 0.61) or high specialization (OR, 0.76; 95% CI, 0.56-1.03; P = 0.073). A decreased risk of illness was associated with greater prior week sleep (OR, 0.79; 95% CI, 0.69-0.91; P < 0.001) and physical activity (OR, 0.94; 95% CI, 0.92-0.96; P < 0.001). CONCLUSION: Sport specialization is not associated with an increased risk of illness among middle school athletes, while increased sleep duration and physical activity appear to reduce the risk of illness. CLINICAL RELEVANCE: Interventions to promote physical activity and improve sleep may reduce the risk of illness in early adolescent athletes.

Long-term effectiveness of a fundamental motor skill intervention in Belgian children: A 6-year follow-up.

The aim of this study was (1) to examine the long-term effectiveness of the "Multimove for Kids" program, a 30-week fundamental motor skill intervention (approximately 1 hour per week) for typically developing children between 3 and 8 years, and (2) to determine the influence of participation in organized sports on motor competence (MC) six years after the intervention. Of the 992 children who took part in the "Multimove" program, 399 (intervention group: N = 228, control group: N = 171) were tested again at 6-year follow-up. MC was measured with the Test of Gross Motor Development, 2nd Edition. To examine the long-term impact of "Multimove" on MC, and the effect of participation in organized sports a latent growth curve analysis was conducted. After the 30-week intervention, the intervention group outperformed the control group (ß = 5.57, P < .001). However, when the entire study period, including the 6-year follow-up, was considered, the intervention group made less progress in MC than the control group (ß = -0.41, P < .05). Looking at the engagement in organized sports, it was found that years of experience before the intervention had no significant influence on the evolution of MC over time, whereas a positive effect was observed for children's average sports participation (h/week) during the 6-year retention period (ß = 0.14, P < .001). Finally, children practicing predominantly object control-oriented sports during retention obtained slightly better MC scores at follow-up (ß = 0.01, P < .01). The "Multimove" intervention does not have a long-term effect on the development of MC. However, participation in organized sports has a positive influence on MC evolution over time.

Short- and Long-Term Stroboscopic Training Effects on Visuomotor Performance in Elite Youth Sports. Part 1: Reaction and Behavior.

PURPOSE: Recent research suggests that stroboscopic training is an effective tool to improve visual and visuomotor performance. However, many studies were limited by small samples, short training interventions, inexperienced athletes, and an exclusive focus on short-term effects. This first part of the study evaluates the short- and long-term effects of stroboscopic training on visuomotor reaction speed in elite athletes. METHODS: Forty-five young elite badminton athletes participated in this study, of which 32 (13.7 yr) were included in the final data analysis. Participants were assigned to an intervention (stroboscopic vision) or control group (normal vision). Both groups performed identical badminton-specific training drills implemented into the regular training schedule. Before and after a 10-wk training period and after a 6-wk retention interval, athletes performed a laboratory reaction test to determine EMG onset and visuomotor reaction time (VMRT). In addition, a field test investigated stroboscopic training effects on the quality of ball-racquet contact and net drop performance. RESULTS: VMRT decreased immediately after stroboscopic training (pre, 251 ms; post, 238 ms; P = 0.005, d = 0.63), and reactions remained significantly faster after the retention interval (retention, 241 ms; P = 0.041, d = 0.50). Analyses on EMG onset data suggested these adaptations were attributable to the premotor rather than the motor time. VMRT remained unchanged in the control group (pre, 252 ms; post, 256; retention, 253 ms; P > 0.99). Field test performance improvements were observed for the quality of ball-racquet contact and net drop performance; however, changes were not different between groups. CONCLUSIONS: Stroboscopic training induced short- and long-term accelerations of visuomotor reaction speed in elite badminton players. Stroboscopic eyewear may be an effective training tool to accelerate visuomotor reactions in highly skilled athletes.

The role of growth, maturation and sporting environment on the development of performance and technical and tactical skills in youth basketball players: The INEX study.

In this paper, we outline a systematic testing programme developed to help identify excellence in youth basketball players. We examine the links between biological maturation and training experience with anthropometry, body composition, physical performance, technical and tactical skills from five age-cohorts, and characterize, in detail, facets of their environment. In total, 238 young basketball players aged 11-15 years, clustered into five age-cohorts (11, 12, 13, 14, 15 years) were recruited. We assessed measures across three domains: (1) biological [anthropometry, body composition, biological maturation and physical performance]; (2) skill/game proficiency [technical skills and tactical skills]; and (3) contextual [family support, coach knowledge and competence and club context]. The data were analysed using one-way ANOVAs and multivariate analysis of covariance adjusting for biological maturation and training experience. We report significant differences favouring older basketball players on most biological and skill/game proficiency variables. However, differences between age-cohorts in physical performance and technical skills were mitigated after controlling for the effects of both covariates. In conclusion, our findings highlight the important role of both biological maturation and training experience on youth basketball players' performance and development. We discuss the implications of these findings for research as well as for athletes, parents, coaches and clubs.

Motor Deficits in Youth with Concussion History: Issues with Task Novelty or Task Demand?

The present study expands previous work on eye-hand decoupling deficits in youth with concussion history. It examines whether deficits can be linked to difficulties adapting to new task constraints or meeting ongoing task demands. Data from 59 youth with concussion history (M=11 months post-concussion) and 55 no history controls were analyzed. All 114 participants (M=12.5 yrs.) performed two touchscreen-based eye-hand coordination tasks: A standard task with vision and motor action in alignment, and an eye-hand decoupling task with both spatially decoupled, with twenty trials per task condition. First (trial 1-4), middle (trial 9-12), and last (trial 17-20) trial blocks were analyzed in each condition across groups, as well as first and last blocks only. The latter analysis showed in the first block longer response times in the concussion history group in the eye-hand decoupling condition due to a general slowdown of the reaction times across blocks and a trend for higher movement times. Our findings suggest that youth with concussion history have difficulty to adapt to new task constraints associated with complex skill performance during a short series of trials. These results are relevant for athletic trainers, therapists and coaches who work with youth with concussion history.

Uninjured Youth Athlete Performance on Single-Leg Hop Testing: How Many Can Achieve Recommended Return-to-Sport Criterion?

BACKGROUND: Current anterior cruciate ligament reconstruction (ACLR) guidelines utilize single-leg hop tests (SLHTs) to assist in return-to-sport decision making. A limb symmetry index (LSI) of ≥90% is often required; however, after ACLR, most youth athletes cannot achieve this standard. Reporting the performance of age-matched normative controls will allow clinicians to compare post-ACLR performance with noninjured peers, improving the utility of SLHTs. The purpose of this study was to report hop test LSI within healthy youth athletes and determine whether athlete performance surpasses post-ACLR requirements. HYPOTHESIS: The LSI for the majority of healthy youth athletes will be ≥90%. STUDY DESIGN: Cross-sectional cohort study. LEVEL OF EVIDENCE: Level 3. METHODS: Each participant performed a single hop (SH), triple hop (TrH), crossover hop (CrH), and timed hop (TiH). A 3-trial mean was utilized to calculate an LSI (nondominant/dominant leg [self-reported kicking leg]) for each hop. The frequency of pass/fail at ≥90% LSI was calculated. Pearson correlation coefficients analyzed the relationship between the different hops, and a 2-way analysis of variance determined the effects of age and sex on LSI. RESULTS: A total of 340 participants (54% male; mean age, 10.9 ± 1.5 years; range, 8-14 years) were included. The mean LSI was >95% for each SLHT (SH, 97.9% [SD, 0.7]; TrH, 96.6% [SD, 0.6]; CrH, 96.8% [SD, 0.8]; TiH, 96.5% [SD, 0.6]). When analyzed as a test battery, only 45% of participants achieved this standard. Significantly weak to moderate correlations existed among hop tests (P < 0.01; r = 0.342-0.520). Age and sex had no effect on LSI (P < 0.05). CONCLUSION: While the mean LSI in our sample was >95% for each individual hop test, participant performance across all SLHT components varied, such that less than half of healthy athletes could achieve ≥90% LSI across all hops. CLINICAL RELEVANCE: Current guidelines require ≥90% LSI on SLHTs. The majority of healthy youth athletes could not achieve this standard, which questions the validity of this LSI threshold in youth athletes after ACLR.

Achieving a desired training intensity through the prescription of external training load variables in youth sport: More pieces to the puzzle required.

Identifying the external training load variables which influence subjective internal response will help reduce the mismatch between coach-intended and athlete-perceived training intensity. Therefore, this study aimed to reduce external training load measures into distinct principal components (PCs), plot internal training response (quantified via session Rating of Perceived Exertion [sRPE]) against the identified PCs and investigate how the prescription of PCs influences subjective internal training response. Twenty-nine school to international level youth athletes wore microtechnology units for field-based training sessions. SRPE was collected post-session and assigned to the microtechnology unit data for the corresponding training session. 198 rugby union, 145 field hockey and 142 soccer observations were analysed. The external training variables were reduced to two PCs for each sport cumulatively explaining 91%, 96% and 91% of sRPE variance in rugby union, field hockey and soccer, respectively. However, when internal response was plotted against the PCs, the lack of separation between low-, moderate- and high-intensity training sessions precluded further analysis as the prescription of the PCs do not appear to distinguish subjective session intensity. A coach may therefore wish to consider the multitude of physiological, psychological and environmental factors which influence sRPE alongside external training load prescription.

Inter-limb asymmetries are associated with decrements in physical performance in youth elite team sports athletes.

Actually, there is scarce literature looking for the relationship between inter-limb asymmetries and performance in youth elite team sports. The main purpose of this cross-sectional study was to examine the relationships between inter-limb asymmetries and physical performance in youth elite team-sports players. A secondary objective was to evaluate the presence of between-sexes differences in inter-limb asymmetries in elite youth team sports players. Eighty-one young elite team-sports athletes (age: u-14 to u-18) performed the star excursion balance test in the anterior direction (SEBT ANT), a single leg vertical countermovement jump test (SLCMJ), the one leg hop test for distance (OLHT), a 30 m sprint test, and the V-cut test. Inter-limb asymmetries were calculated for SEBT ANT, SLCMJ and OLHT. Pearson r was used to analyse the relationships between inter-limb asymmetries and physical performance. Results showed significant (p < 0.05) but small (r = 0.26) relationships between SLCMJ asymmetries and 30 m sprint time for the total group. Significant negative correlations with small to moderate magnitude of correlation were also found between SLCMJ asymmetries and SLCMJ performance on the lowest performing limb for the total group (p < 0.05; r = -0.26), males (p < 0.01; r = -0.48) and females (p < 0.05; r = -0.30). Moreover, significant negative correlations with moderate and large magnitude were also present between OLHT asymmetries and OLHT performance on the lowest performing limb for the total group (p < 0.01; r = -0.44), males (p < 0.01; r = -0.56) and females (p < 0.01; r = -0.64). No correlations were observed between asymmetries and either the V-cut test or SEBT ANT performance. No correlation were observed between SEBT ANT asymmetries and physical performance. In addition, when comparing asymmetry values between sexes there were no significant differences in vertical (p = 0.06) and horizontal (p = 0.61) jumping tests. However, there were significant differences in asymmetry between sexes in the ANT SEBT (p = 0.04). In conclusion, the current study indicated that jumping asymmetries were associated with decrements in sprint speed and jumping performance. Therefore, assessing inter-limb asymmetries would be recommended to improve training interventions for youth elite team-sports athletes.