How Young is "Too Young" to Start Training?

Allostatic load score and lifestyle factors in the SWAN cohort: A longitudinal analysis

Objectives

Allostatic load (AL) has been used to assess chronic stress. Previous studies have assessed associations between lifestyle factors and the AL. However, those studies have yet to evaluate associations longitudinally. Thus, the effect of lifestyle factors on the AL changes over time remains to be determined.

Study design

A longitudinal analysis was designed.

Methods

Our study included 1976 women identified from the Study of Women's Health Across the Nation (SWAN) who had completed at least seven waves of measurements since baseline. The Poisson mixed effects model was used to model AL and to assess how lifestyle factors affected AL over time.

Results

At baseline, the mean AL score was 2.44 (range 0-11). On average, the AL score increased by 3 % (ORs = 1.03, 95 % CI [1.01, 1.05]) per wave over time. For lifestyle factors, women who smoked cigarettes over time had higher AL than those who never smoked. On the other hand, women who ever drank alcohol at baseline, had leisure physical activity over time, and had at least average sleep quality at baseline, and had lower AL than their counterparts. We also identified a statistically significant interaction between alcohol drinking and time (P < 0.01). Furthermore, we generated a healthy score using the four lifestyle factors above to assess the potential accumulative effect of lifestyle factors on AL. We found that the AL increased by 16 % for each additional unhealthy lifestyle factor (ORs = 1.16, 95%CI: 1.12, 1.2).

Conclusions

This study demonstrates that lifestyle factors can influence the increase of AL over time.

A systematic review and network meta-analysis on the effectiveness of exercise-based interventions for reducing the injury incidence in youth team-sport players. Part 2: an analysis by movement patterns

The objectives of this network meta-analysis were: (a) to estimate and compare the pooled effects of some injury prevention programs (IPPs) whose exercise-based components were categorized using a movement pattern-specific taxonomy on reducing overall and some specific body regions (lower extremity, thigh, knee, and ankle) injury incidences in youth team sport athletes and (b) to explore the individual effects of these components on the injury incidence rates (IIRs) previously mentioned. Searches were performed in PubMed, Web of Science, SPORTDiscus, and Cochrane Library. Eligible criteria were: exercise-based interventions comprised of exercises involving athletic motor skill competencies and evaluated against a control group, overall IIRs were reported, and youth (≤19 years old) team sport players. For the current analysis, a taxonomy based on movement patterns was employed for exercise component identification (upper body pushing and pulling; lower body concentric and eccentric; core; mechanics; acceleration; and lower body stability). Pooled effects were calculated by frequentist random effects pairwise and network meta-analyses. Nineteen studies were included. Most of the IPPs exhibit risk reduction when compared to their control groups on overall, lower extremity, and ankle injuries. Interventions comprised of lower body concentric and eccentric, core, mechanics, and lower body stability exercises were the most effective measures for reducing these injuries. None of the IPPs demonstrated to be effective for reducing thigh injuries, and contradictory results were found for knee injuries. Individual analysis at component level revealed that the lower body (bilateral and unilateral, concentric, and eccentric) component was the only one associated with a significant reduction on overall injuries. Indirect evidence suggests that interventions incorporating lower body concentric and eccentric, core, mechanics, and lower body stability exercises might be the most effective for reducing overall, lower extremity, and ankle injuries in youth team sports.

A Kinetic Enhanced Tuck Jump Assessment Exposes Residual Biomechanical Deficits in Female Athletes 9 Months Post Anterior Cruciate Ligament Reconstruction

ABSTRACT

Kember, LS, Riehm, CD, Schille, A, Slaton, JA, Myer, GD, and Lloyd, RS. Residual biomechanical deficits identified with the tuck jump assessment in female athletes 9 months after ACLR surgery. J Strength Cond Res 38(12): 2065-2073, 2024-Addressing biomechanical deficits in female athletes after anterior cruciate ligament reconstruction (ACLR) is crucial for safe return-to-play. The tuck jump assessment (TJA) is used to identify risks associated with ACL injury, yet its fundamental analyses lack the ability to explore landing forces. Kinetic asymmetries during the TJA were assessed in athletes with ACLR (n = 38) and matched healthy controls (n = 21) using discrete time-point analysis and statistical parametric mapping (p < 0.05). The ACLR group performed fewer jumping cycles with distinct kinetic differences, including longer ground contact time (g = 1.45), larger peak center of mass displacement (g = 1.29), and lower peak vertical ground reaction force (VGRF) (g = -2.05) and relative leg stiffness (g = -1.51). Greater interlimb kinetic asymmetries were evident in the ACLR group for VGRF (g = 0.84), relative leg stiffness (g = 0.85), average loading rate (g = 0.84), peak braking force (g = 0.85), and time of braking (g = 0.80) and propulsive peaks (g = 1.04). Moderate differences in VGRF favored the uninvolved limb of the ACLR group for the majority (2-100%) of the stance phase of TJA (d = -0.52). Distinct jump-landing strategies between ACLR athletes and healthy controls were revealed during the TJA, which may indicate compromised stretch-shortening cycle function. Findings highlight the need for targeted rehabilitation to foster greater kinetic symmetry in jump-landing performance and underscore the importance of longitudinal and progressive monitoring for optimized return-to-play outcomes in athletes after ACLR.

Interlimb kinetic asymmetries during the tuck jump assessment are more exposed following kinetic stabilization

OBJECTIVE

To analyse interlimb kinetics and asymmetries during the tuck jump assessment (TJA), before and after kinetic stabilization, to identify injury risk in healthy female athletes.

DESIGN

Cross-sectional study.

SETTING

Laboratory.

PARTICIPANTS

Twenty-five healthy females (age 21.0 ± 1.83 yrs; height 1.68 ± 0.06 m; body mass 69.4 ± 10.7 kg).

MAIN OUTCOME MEASURES

Kinetics were measured during 10-s trials of the TJA and absolute asymmetries compared, before and after kinetic stabilization using paired sample t-tests. Statistical parametric mapping (SPM) compared vertical ground reaction force (VGRF) data for each limb during the jumping cycles before and after stabilization.

RESULTS

Small to moderate increases in interlimb asymmetries were observed after stabilization for VGRF, relative vertical leg stiffness, average loading rate, total and propulsive impulse, peak braking and propulsive force (p < 0.05). SPM revealed significant interlimb differences between 77-98% and 83-99% of ground contact for the jumping cycles pre- and post-stabilization respectively.

CONCLUSIONS

Larger asymmetries were evident after kinetic stabilization, with increased VGRF in the non-dominant limb. We speculate that participants sacrificed interlimb landing symmetry to achieve kinetic stability, which may reflect a primal landing strategy that forgoes movement quality. Assessing lower limb biomechanics using the TJA should involve examining kinetic stability and interlimb kinetic asymmetries.

Biological maturation, contextual factors, and future career in basketball: A possible interrelationship?

This study aimed to analyse the relationship between the maturational state and contextual factors with future basketball career success in Under-16 (U16) Portuguese youth preparing for the U16 European Basketball Championships. Eighty-five Under-15 (U15) and U16 male basketball players (height: 189.7 ± 6.53 cm; body mass: 81.1 ± 9.96 kg; the age of peak height velocity: 13.3 ± 0.7 y) were selected by the Portuguese national coaching staff to participate in a national team training camp in 2016, 2017, and 2018 years. A binary logistic regression was employed to identify the influence of maturation, born quartile, demographic, geographic and economic characteristics, and sport career (i.e., drop out during first season and chance of playing professionally). Early maturing players were typically classified as inside players. Training experience and predicted adult height, and type of first club were able to predict players who dropped out during their first season at senior level (both p < 0.01). No variables were able to predict who played in a professional league during their first season at senior level. Practitioners should use these data to consider how national level basketball players are identified and developed, but also keep in mind of their specific contextual factors.

National Strength and Conditioning Association Position Statement on Weightlifting for Sports Performance

ABSTRACT

Comfort, P, Haff, GG, Suchomel, TJ, Soriano, MA, Pierce, KC, Hornsby, WG, Haff, EE, Sommerfield, LM, Chavda, S, Morris, SJ, Fry, AC, and Stone, MH. National Strength and Conditioning Association position statement on weightlifting for sports performance. J Strength Cond Res XX(X): 000-000, 2022-The origins of weightlifting and feats of strength span back to ancient Egypt, China, and Greece, with the introduction of weightlifting into the Olympic Games in 1896. However, it was not until the 1950s that training based on weightlifting was adopted by strength coaches working with team sports and athletics, with weightlifting research in peer-reviewed journals becoming prominent since the 1970s. Over the past few decades, researchers have focused on the use of weightlifting-based training to enhance performance in nonweightlifters because of the biomechanical similarities (e.g., rapid forceful extension of the hips, knees, and ankles) associated with the second pull phase of the clean and snatch, the drive/thrust phase of the jerk and athletic tasks such as jumping and sprinting. The highest force, rate of force development, and power outputs have been reported during such movements, highlighting the potential for such tasks to enhance these key physical qualities in athletes. In addition, the ability to manipulate barbell load across the extensive range of weightlifting exercises and their derivatives permits the strength and conditioning coach the opportunity to emphasize the development of strength-speed and speed-strength, as required for the individual athlete. As such, the results of numerous longitudinal studies and subsequent meta-analyses demonstrate the inclusion of weightlifting exercises into strength and conditioning programs results in greater improvements in force-production characteristics and performance in athletic tasks than general resistance training or plyometric training alone. However, it is essential that such exercises are appropriately programmed adopting a sequential approach across training blocks (including exercise variation, loads, and volumes) to ensure the desired adaptations, whereas strength and conditioning coaches emphasize appropriate technique and skill development of athletes performing such exercises.

The Risk Factors Associated with Grip Lock Injuries in Artistic Gymnasts: A Systematic Review

Artistic gymnastics (AG) is a sport that demands grace, strength, and flexibility, leading to a broad spectrum of injuries. The dowel grip (DG) is widely used by gymnasts to securely hold onto the high bar or uneven bars. However, incorrect usage of the DG can result in grip lock (GL) injuries. This systematic review aims to (1) identify studies that have investigated the risk factors related to GL injuries among gymnasts and (2) synthesize the key evidence. A comprehensive electronic search was conducted in the following databases: PubMed, ScienceDirect, Elsevier, SportDiscus, and Google Scholar, covering the period from their inception until November 2022. The data extraction and analysis were independently completed by two investigators. A total of 90 relevant studies were initially identified, out of which seven clinical trials met the eligibility criteria. For the quantitative synthesis, five studies were included. The details extracted from each article include: the sample characteristics (number, gender, age, and health status), the study design, the instrumentation or intervention used, and the final results. Our results revealed that the underlying causes of the risk factors of GL injuries were the irregular checking of the dowel grip and the mating surface of the bar, the tearing of the dowel of the leather strap, and the use of the dowel grip in different competition apparatuses. In addition, GL injuries may occur either as severe forearm fractures or mild injuries. Excessive flexion of the forearm and overpronation of the wrist during rotational movements, such as the swing or backward/forward giant circle, may increase the possibility of GL injury on the high bar. Future studies should focus on GL injury prevention strategy and rehabilitation protocol for GL injuries. Further high-quality research is required to establish the validity of these findings.

Increased Risk of Concomitant Meniscal Injuries in Adolescents With Elevated Body Mass Index After Anterior Cruciate Ligament Tear: A Systematic Review

PURPOSE

To investigate existing studies examining the association between body mass index (BMI) and outcomes of anterior cruciate ligament reconstruction (ACLR) in adolescent patients.

METHODS

A literature search was conducted on PubMed and Embase. Studies examining associations between BMI and outcomes after ACLR in adolescents were included. Quality assessment was performed. Data on patient age, sex, study design, time of follow-up, sample size, graft type, concomitant injuries (meniscal injury, surgical procedures), clinical outcomes (revision ACLR, postoperative weight gain, post-traumatic osteoarthritis [PTOA], range of motion [ROM]), and functional outcome (muscle strength) were extracted.

RESULTS

Eleven papers of Levels II-IV evidence were included. Five studies found positive correlations between BMI and risk of concomitant meniscal injuries. Two of them reported young patients with elevated BMI having 1.6 times greater odds of requiring meniscectomy (P < .01) and 1.031 times greater odds of requiring concomitant surgeries (P = .011). One study showed significant positive association of postoperative weight gain by time (r = 0.28, P < .01), with smaller increase in the overweight and obese groups compared with the normal-weight group. One study demonstrated greater cartilage breakdown in young patients with overweight and obesity postsurgery, contributing to PTOA (r = 0.42, P = .009). There was no clinically important difference in postoperative ROM and muscle strength. Four studies reviewed the association between BMI and revision ACLR risk, but results were heterogeneous and a firm conclusion cannot be drawn.

CONCLUSIONS

Adolescents with elevated BMI are more likely to have concomitant meniscal injuries and surgical procedures after ACL tear. There is some weak evidence of the association of elevated BMI with PTOA and slight postoperative weight gain post-ACLR. There may not be any clinically significant association of obesity with post-operative muscle strength and ROM, and current studies are inconclusive regarding the impact of BMI on revision ACLR risk.

LEVEL OF EVIDENCE

Level IV, systematic review of Level II-IV studies.

Mind the gap! A survey comparing current strength training methods used in men's versus women's first team and academy soccer

PURPOSE

Much less is known about strength and conditioning (S&C) practice in women's versus men's soccer. The aim of this study was to compare S&C practice between coaches working in men's or women's soccer, at first team or academy level, worldwide.

METHODS

A total of 170 participants, who were involved with S&C support at their soccer club (in Europe, USA and South America, within men's or women's first team or academy settings) completed a comprehensive online survey, designed to evaluate (i) their academic qualifications and S&C coaching experience; and their preferred methods for (ii) physical testing; (iii) strength and power development; (iv) plyometric training; (v) speed development; and (vi) periodization.

RESULTS

Women's academies had fewer weekly in-season S&C sessions than men's academies (1.6±0.6 vs. 2.3±0.9, p=0.005). Relatively, fewer women's academy S&C coaches (6%) used Olympic weightlifting movements than men's academy S&C coaches (32%, p=0.030). Relatively, more women's academy coaches (47%) used the Nordic hamstring exercise (NHE) compared to men's academy coaches (15%, p=0.006), but relatively more women's vs. men's first team coaches (61% vs. 38%, p=0.028) and women's vs. men's academy (61% vs. 38% coaches, p=0.049) utilised rating of perceived exertion-based load prescriptions.

CONCLUSION

Notable differences in S&C practice exist between coaches of men's and women's soccer squads, particularly at academy level. Fewer weekly S&C sessions in women academy players may have implications for physical development, while the greater use of subjective load prescriptions in both academy and first team women's squads may lead to sub-optimal performance gains.

Effects of Integrative Neuromuscular Training on Motor Performance in Prepubertal Soccer Players

ABSTRACT

Menezes, GB, Alexandre, DR, Pinto, JC, Assis, TV, Faigenbaum, AD, and Mortatti, AL. Effects of integrative neuromuscular training on motor performance in prepubertal soccer players. J Strength Cond Res 36(6): 1667-1674, 2022-The present study examined the effects of integrative neuromuscular training (INT) on motor performance in prepubertal soccer players. Subjects were randomly assigned to the experimental group (INT; n = 20, age: 8.2 ± 1.2 years; body mass: 28.4 ± 6.4 kg; height: 1.3 ± 0.1 m) or the control group (CON; n = 18, age: 8.5 ± 1.3 years; body mass: 32.8 ± 8.9 kg; height: 1.3 ± 0.1 m). Integrative neuromuscular training program was performed twice per week during the 12-week training intervention. Balance, flexibility, countermovement vertical jump height (CVJH), sprint speed, and change of direction speed (CODS) were assessed in both groups at baseline, sixth week and 12th week. A mixed model repeated measures analysis of variance was used to examine the group changes in performance for each variable. There was a time effect for balance in the INT from pre to 12th weeks (p < 0.001, g = 0.72), and from 6th to 12th weeks (p = 0.005, g = 0.34). An interaction effect for balance was also observed between INT and CON after the 12th week. A time effect in flexibility was observed in INT from baseline to 6th and 12th weeks (p = 0.02; g = 0.45 and p < 0.001; g = 0.71) and from 6 to 12th weeks (p = 0.003; g = 0.24). There was a time effect in CVJH, from baseline to 12th week and from 6th to 12th weeks (p < 0.05; g = 0.34 and g = 0.53, respectively). There was no significant between-group speed performance change. A time effect was found in CODS in INT, but only from baseline to 12th week (p = 0.02; g = 0.31). There were significant improvements in the percent change (Δ%) from baseline to 12 weeks (p < 0.05) for balance, flexibility, and CVJH in INT. These findings indicate that the addition of an INT program to soccer practice can improve selected motor performance skills in prepubertal soccer players.

Selection Process for Romanian Children in Handball Based on Coordinative Abilities: A Questionnaire Survey

According to the reviewed literature, the selection system in handball is quite complex and requires new approaches from trainers based on the current and modern requirements of this game. This paper investigated the importance of coordinative ability development in handball in the selection process for young Romanian children (10–12 years old). The results were obtained from a sociological questionnaire survey, for which 109 handball coaches, 34 female and 75 male, were questioned. The mean age was 40.71 years (SD = ±5.32) with a range of 31–51 years for female coaches and 40.3 years (SD = ±7.53) with a range of 30–62 years for male coaches. Their experience in handball coaching varied from 10 to 30 years, with 19.88 (SD = ±5.05) years of experience on average for female coaches and 19.09 (SD = ±5.26) years of experience on average for male coaches. The answers delivered depended on the experience and knowledge the coaches had and difficulties they had encountered over the years. Data are presented using a variety of appropriate descriptive statistics, including frequencies, percentages, and mean and standard variation. Obtained data were modeled using a one-way analysis of variation (ANOVA). The questionnaire format was three-to-five-point Likert scale. As a general overview, in the opinion of the surveyed specialists, the Romania selection process for handball does not meet their expectations, and the development level of coordinative abilities in 10–12 year-old children is medium to weak. A total of 61.76% female and 58.66% male coaches stressed the importance of developing coordination abilities to optimize the selection process of children for handball games, opening up a new approach in modern training methods for performance achievement. The obtained results from this paper questionnaire can be used by coaches as a different approach to the handball training process, considering that handball is a game mainly based on coordination.

A Glimpse of the Sports Nutrition Awareness in Spanish Basketball Players

Basketball is a team sport, with many fans and practitioners worldwide from all ages and levels. In all cases, players accumulate high levels of fatigue, and there is also limited time to recover between games or practices. In particular, nutrition plays a key role in optimizing performance and recovery. However, it is typical to observe erroneous nutritional behaviors among basketball players. It has been theorized that these behaviors are influenced by habits acquired based on the individual’s knowledge. Therefore, the main aim of this study was to conduct a descriptive research of the sports nutrition knowledge and practices in a sample of Spanish basketball players, from athletes under 18 years old (n = 69) to nonprofessional (n = 14) and professional adult players (n = 21). The sample was comprised of 49 men and 55 women. This was a transversal, cross-sectional, observational and descriptive study. All participants (n = 104) completed an anonymous online survey in order to analyze their sports nutrition knowledge and practices. In view of the obtained results, we can conclude that the knowledge of sport-specific nutrition in players under 18 years old, as well as non-professional and professional adult basketball players, is insufficient through all the categories and levels. The lack of professional support and time management difficulties were identified as some of the main barriers.

Rethinking physical exercise training in the modern era of cystic fibrosis: A step towards optimising short-term efficacy and long-term engagement

Exercise is considered as an important component of the package of care delivered to people with cystic fibrosis (pwCF). However, despite the well-known short-term physiological and psychological benefits, training effects are heterogenous and the transfer of structured exercise programmes to the daily life of pwCF is challenging. Training concepts and strategies developed over the last decades must be adapted to consider the aging population of pwCF with associated comorbidities, and also a new generation of young pwCF that are healthier than ever. In the present review we propose a new framework for optimising the choice among available exercise training procedures and we provide a theoretical and scientifically justified rationale for considering and testing new exercise training modalities. We propose a multidisciplinary approach, considering various physiological, psychological and logistical factors, with the aim to increase effects of exercise training and build positive long-term exercise behaviour.

Effects of Integrative Neuromuscular Training and Detraining on Countermovement Jump Performance in Youth Volleyball Players

ABSTRACT

Nunes, ACCA, Cattuzzo, MT, Faigenbaum, AD, and Mortatti, AL. Effects of integrative neuromuscular training and detraining on countermovement jump performance in youth volleyball players. J Strength Cond Res 35(8): 2242-2247, 2021-The purpose of this study was to analyze the effect of integrative neuromuscular training (INT) on countermovement vertical jump height (CVJH) performance in youth volleyball players before and after a detraining period. Thirty-two novice volleyball players were cluster randomized into 2 groups: intervention group-INT (age: 13.1 ± 0.4 years; body mass: 55.3 ± 12.1 kg; and height: 161.1 ± 6.4 cm) and control group-CON (age: 12.8 ± 0.7 years; body mass: 51.8 ± 13.6 kg; and height: 160.1 ± 10.7 cm). The subjects were evaluated for somatic maturation (years from peak height velocity) and for CVJH performance at 4 time points during the 20-week study period: baseline, 6 weeks of INT, 12 weeks of INT, and 8 weeks after INT (detraining). The analysis used repeated-measures analysis of variance and Bonferroni post hoc test to identify possible differences in the CVJH delta in both groups. Spearman correlation was performed to verify the association between the values of the vertical jump tests and maturational levels found. The INT showed a significant improvement in the CVJH from baseline to 12 weeks and maintained training-induced gains after detraining period (p > 0.001). Significant increase in CVJH was found in the percentage of change (Δ%) from baseline to 6 weeks (p < 0.005), 12 weeks (p < 0.001), and detraining (p < 0.001) in INT compared with the CON. The results of this study indicate that INT was able to improve CVJH performance in novice youth volleyball players and these gains were sustained during the detraining period. These findings indicate that regular participation in supervised INT can enhance jumping performance in young volleyball players, and that this type of neuromuscular program may be particularly beneficial for youth with limited fundamental motor skill performance.

A Pedagogical Approach to Integrative Neuromuscular Training to Improve Motor Competence in Children: A Randomized Controlled Trail

Font-Lladó, R, López-Ros, V, Montalvo, AM, Sinclair, G, Prats Puig, A, and Fort-Vanmeerhaeghe, A. A pedagogical approach to integrative neuromuscular training to improve motor competence in children: a RCT. J Strength Cond Res 34(11): 3078-3085, 2020-To assess the effectiveness of a pedagogical approach to an integrative neuromuscular training (INT) program as a warm-up in physical education (PE) lessons in healthy children: (a) to improve the level of motor competence (MC) and (b) to master fundamental motor skills (FMS) patterns, considering the baseline MC level and the time spent when performing different motor tasks. One hundred ninety students (7.43 ± 0.32 years; 52% girls) were included in this randomized controlled trail and grouped up according to MC basal levels (L1-L4). Motor competence and FMS patterns (CAMSA protocol) were assessed before and after the intervention in a group-based INT warm-up (n = 97) and a group-based conventional warm-up (n = 93). The INT program improved MC (p < 0.001; d = 0.71) and FMS (p < 0.001, d = 0.52). The independent predictors of MC change were: baseline MC level (β = -196; p < 0.012), time spent to perform the task (β = -0.235 p < 0.003), and participation in the INT program (β = 0.201; p < 0.005), explaining 71% of its variability. The INT warm-up shows correlations between improvements in MC in relation to time reduction (L1 p = 0.016, d, L2 p = 0.001, and L4 = 0.001) and FMS patterns (L1 p < 0.001, L2 p < 0.003, L3 p < 0.005, and L4 < 0.001) Moreover, only L3, it showed correlation between changes in time and FMS mastery (p = 0.001). Our results showed that a pedagogical approach to an INT program developed as a warm-up in primary school PE lessons can improve MC and FMS patterns in all subjects, independent of the initial MC level. More interestingly, only in L3, the improvement in MC can be explained by the balance in time required to perform the task and the level of improvement in FMS patterns.

Selected Musculoskeletal Issues in Adolescents

Musculoskeletal care of the adolescent patient involves unique knowledge of their rapidly changing physical and psychological health. In this article, the importance of preventing early sports specialization is elucidated, and an encouragement of the safety and necessity of resistance training in adolescents is undertaken. It also explores two common conditions, one affecting the immature skeleton (apophysitis), and one affecting the improperly developed muscular system (patellofemoral syndrome), both of which are diagnosed clinically, and require little advanced imaging. Finally, a brief overview of relative energy deficiency in sport is given.

Part II: Comparison of Crossfit-Related Injury Presenting to Sports Medicine Clinic by Sex and Age

OBJECTIVE

To examine CrossFit-related injuries based on sex and age.

DESIGN

Retrospective case series.

SETTING

A tertiary-level pediatric sports medicine clinic.

PARTICIPANTS

CrossFit athletes.

MAIN OUTCOME MEASURES

CrossFit-related injuries by sex (males vs females) and age groups (≤19 years vs >19 years) using a χ analysis with P = 0.05, odds ratio (OR), and 95% confidence interval (95% CI).

RESULTS

Among injured CrossFit athletes, female athletes sustained lower extremity injuries more frequently than male athletes (P = 0.011; OR, 2.65; 95% CI, 1.25-5.65). In observed CrossFit injuries, shoulder injuries were more frequently observed in male athletes compared with female athletes (P = 0.049; OR, 2.79; 95% CI, 0.98-7.95). Additionally, a greater proportion of CrossFit athletes aged 19 years and younger suffered trunk/spine injuries than those older than 19 years (P = 0.027; OR, 2.61; 95% CI, 1.10-6.21) in injured CrossFit athletes.

CONCLUSIONS

The current results indicated sex- and age-specific susceptibility to CrossFit-related injuries based on body parts and diagnoses. The presented information may be useful to develop a safer exercise program, especially for pediatric and adolescent CrossFit participants.

The stretch-shortening cycle efficiency is dependent on the maturational stage

Abstract Maturation interferes with physiological and mechanical aspects of muscle contraction. The aim of the present study was to compare the efficiency of the stretch-shortening cycle (SSC) between different maturation stages. One hundred forty six young people, with 72 boys and 74 girls, were recruited to participate in the study. Sexual maturation was measured and the group was stratified into adolescents (> 3 auto-tanner) and children (<2 auto-tanner). Squat jump (SJ) and countermovement jump (CMJ) performance were measured to measure reactive force (RF) capacity, eccentric utilization ratio (EUR) and pre-stretch augmentation (PSAP). The children did not present statistical difference between SJ and CMJ (t(55)= -1.93; ∆ = -0.61; 95% CI = -1.24 to -0.02; p = 0.058), while the adolescents presented higher performance of CMJ (t(89)= -12.28; ∆ = -2.44; 95% CI = -2.84 to -2.05; p <0.001). In addition, adolescents had higher RF performance (t(144)= 5.18; p <0.0001; 95% CI = 2.53 to 1.13), PSAP (t(144)= 4.38; p <0.0001; 95% CI = 14.00 to 5.29) and EUR (t(144)= 4.38; p <0.0001; 95% CI = 0.14 to 0.05). We conclude that more mature young people have better SSC utilization.

Effects of Plyometric Training on Physical Performance of Young Male Soccer Players: Potential Effects of Different Drop Jump Heights

PURPOSE

To compare the effects of plyometric drop jump (DJ) training against those induced by regular soccer training and assess the transference effect coefficient (TEC) of DJs ("trained exercises") performed from 20- (DJ20) and 40-cm (DJ40) height boxes with respect to different physical qualities (jumping, linear and change of direction speed, kicking, endurance, and maximal strength) in youth male soccer players.

METHODS

Participants were randomly divided into a control group (n = 20; age: 13.5 [1.9] y) and a DJ training group (n = 19; age: 13.2 [1.8] y), and trained for 7 weeks. A 2-way analysis of variance for repeated measures with the within-subject factor time (preintervention and postintervention) and between-subject factor group (intervention vs control) was performed. To calculate the TECs between the trained exercises (DJ20 and DJ40) and the physical tests, the ratio between the "result gains" (effect size [ES]) in the analyzed physical qualities and the result gains in the trained exercises were calculated. The TECs were only calculated for variables presenting an ES ≥ 0.2.

RESULTS

Significant improvements (ES = 0.21-0.46; P < .05) were observed in the DJ training group, except in linear sprint performance. The control group improved only the maximal strength (ES = 0.28; P < .05). Significant differences were observed in all variables (ES = 0.20-0.55; P < .05) in favor of the DJ training group, except for maximal strength (group × time interaction).

CONCLUSIONS

A plyometric training scheme based on DJs was able to significantly improve the physical performance of youth male soccer players. Overall, greater TECs were observed for DJ40 (0.58-1.28) than DJ20 (0.55-1.21).

Virtual Reality As a Training Tool to Treat Physical Inactivity in Children

Lack of adequate physical activity in children is an epidemic that can result in obesity and other poor health outcomes across the lifespan. Physical activity interventions focused on motor skill competence continue to be developed, but some interventions, such as neuromuscular training (NMT), may be limited in how early they can be implemented due to dependence on the child's level of cognitive and perceptual-motor development. Early implementation of motor-rich activities that support motor skill development in children is critical for the development of healthy levels of physical activity that carry through into adulthood. Virtual reality (VR) training may be beneficial in this regard. VR training, when grounded in an information-based theory of perceptual-motor behavior that modifies the visual information in the virtual world, can promote early development of motor skills in youth akin to more natural, real-world development as opposed to strictly formalized training. This approach can be tailored to the individual child and training scenarios can increase in complexity as the child develops. Ultimately, training in VR may help serve as a precursor to "real-world" NMT, and once the child reaches the appropriate training age can also augment more complex NMT regimens performed outside of the virtual environment.

Injury prevention in male youth soccer: Current practices and perceptions of practitioners working at elite English academies

Forty-one practitioners inclusive of physiotherapists, sports scientists and strength and conditioning coaches from the academies of elite soccer clubs in the United Kingdom completed an on-line questionnaire which examined their: (1) background information; (2) perceptions of injury occurrence and risk factors; (3) screening and return to play; and (4) approach to designing and delivering injury prevention programmes with a response rate of 55% (41/75). Contact injuries were the most common mechanism reported and players between 13-16 years of age were perceived to be at the greatest risk. Pertinent risk factors included: reduced lower limb and eccentric hamstring strength, proprioception, muscle imbalances, and under developed foundational movement skills. Joint range of motion, jump tests, the functional movement screen, overhead and single leg squats were the most utilised screening methods. Training modalities rated in order of importance included: resistance training, flexibility development, agility, plyometrics and balance training. Training frequency was most commonly once or twice per week, during warm-ups, independent sessions or a combination of both. Injury prevention strategies in this cohort appear to be logical; however, the classification of injury occurrence and application of screening tools to identify "at risk" players do not align with existing research. The frequency and type of training used may also be insufficient to elicit an appropriate stimulus to address pertinent risk factors based on current recommendations.

Resistance Training in Youth: Laying the Foundation for Injury Prevention and Physical Literacy

CONTEXT

The rising incidence of physical activity- and sports-related injuries has prompted the present-day investigation of resistance training as a potential means of injury prevention and physical literacy development among youth.

EVIDENCE ACQUISITION

Relevant studies on the topics of athlete development, physical literacy, resistance training, and injury prevention in children and adolescents were reviewed (PubMed and Sports Discus, 1982-2016). Recommendations from consensus guidelines and position statements applicable to resistance training and injury prevention in youth, in addition to young athlete development, were reviewed. Additionally, hand searches, expert requests, article reference lists, and gray literature were utilized and reviewed for pertinent content.

STUDY DESIGN

Clinical review.

LEVEL OF EVIDENCE

Level 4.

RESULTS

Youth throughout the physical activity spectrum are at risk for physical activity- and sports-related injury. Of highest priority are early specializers, physically inactive youth, and young girls, owing to increased injury rates. Resistance training among these at-risk populations has been shown to reduce injury risk by up to 68% and improve sports performance and health measures, in addition to accelerating the development of physical literacy. Recent recommendations, position statements, and national initiatives advocate for the incorporation of resistance training with qualified instruction among these groups.

CONCLUSION

Resistance training in addition to free play and other structured physical activity training can serve as a protective means against injury and a positive catalyst for the development of physical literacy to offset the impact of diminishing physical activity and early sport specialization in today's youth.

National Strength and Conditioning Association Position Statement on Long-Term Athletic Development

There has recently been a growing interest in long-term athletic development for youth. Because of their unique physical, psychological, and social differences, children and adolescents should engage in appropriately prescribed exercise programs that promote physical development to prevent injury and enhance fitness behaviors that can be retained later in life. Irrespective of whether a child is involved in organized sport or engages in recreational physical activity, there remains a need to adopt a structured, logical, and evidence-based approach to the long-term development of athleticism. This is of particular importance considering the alarmingly high number of youth who fail to meet global physical activity recommendations and consequently present with negative health profiles. However, appropriate exercise prescription is also crucial for those young athletes who are physically underprepared and at risk of overuse injury because of high volumes of competition and an absence of preparatory conditioning. Whether the child accumulates insufficient or excessive amounts of exercise, or falls somewhere between these opposing ends of the spectrum, it is generally accepted that the young bodies of modern day youth are often ill-prepared to tolerate the rigors of sports or physical activity. All youth should engage in regular physical activity and thus should be viewed as "athletes" and afforded the opportunity to enhance athleticism in an individualized, holistic, and child-centered manner. Because of emerging interest in long-term athletic development, an authorship team was tasked on behalf of the National Strength and Conditioning Association (NSCA) to critically synthesize existing literature and current practices within the field and to compose a relevant position statement. This document was subsequently reviewed and formally ratified by the NSCA Board of Directors. A list of 10 pillars of successful long-term athletic development are presented, which summarize the key recommendations detailed within the position statement. With these pillars in place, it is believed that the NSCA can (a) help foster a more unified and holistic approach to long-term athletic development, (b) promote the benefits of a lifetime of healthy physical activity, and

Physical characteristics of elite adolescent female basketball players and their relationship to match performance

There were two aims of this study: first, to investigate physical fitness and match performance differences between under-16 (U16) and under-18 (U18) female basketball players, and second, to evaluate the relationship between physical fitness and game-related performances. Twenty-three young, female, elite Spanish basketball players (16.2 1.2 years) participated in the study. The sample was divided into two groups: U16 and U18 players. The average scores from pre- and post-season physical fitness measurements were used for subsequent analyses. Anthropometric variables were also measured. To evaluate game performance, game-related statistics, including the number of games and minutes played, points, rebounds, assists, steals and blocks per game, were recorded for every competitive match in one season. When anthropometric and physical performance variables were compared between groups, the U18 group demonstrated significantly (p<0.05) higher values in upper (+21.2%) and lower (+27.11%) limb strength compared to the U16 group. Furthermore, no significant differences between groups were observed in match performance outcomes. Only two performance variables, steals and assists per game, correlated significantly with jump capacity, speed, agility, anaerobic power, repeated sprint ability and aerobic power (p ≤ 0.005). These findings can help optimize training programs for young, elite female basketball players.

A Comparison of Athletic Movement Among Talent-Identified Juniors From Different Football Codes in Australia: Implications for Talent Development

Woods, CT, Keller, BS, McKeown, I, and Robertson, S. A comparison of athletic movement among talent-identified juniors from different football codes in Australia: implications for talent development. J Strength Cond Res 30(9): 2440-2445, 2016-This study aimed to compare the athletic movement skill of talent-identified (TID) junior Australian Rules football (ARF) and soccer players. The athletic movement skill of 17 TID junior ARF players (17.5-18.3 years) was compared against 17 TID junior soccer players (17.9-18.7 years). Players in both groups were members of an elite junior talent development program within their respective football codes. All players performed an athletic movement assessment that included an overhead squat, double lunge, single-leg Romanian deadlift (both movements performed on right and left legs), a push-up, and a chin-up. Each movement was scored across 3 essential assessment criteria using a 3-point scale. The total score for each movement (maximum of 9) and the overall total score (maximum of 63) were used as the criterion variables for analysis. A multivariate analysis of variance tested the main effect of football code (2 levels) on the criterion variables, whereas a 1-way analysis of variance identified where differences occurred. A significant effect was noted, with the TID junior ARF players outscoring their soccer counterparts when performing the overhead squat and push-up. No other criterions significantly differed according to the main effect. Practitioners should be aware that specific sporting requirements may incur slight differences in athletic movement skill among TID juniors from different football codes. However, given the low athletic movement skill noted in both football codes, developmental coaches should address the underlying movement skill capabilities of juniors when prescribing physical training in both codes.

Sports Specialization, Part II: Alternative Solutions to Early Sport Specialization in Youth Athletes

Context:

Many coaches, parents, and children believe that the best way to develop elite athletes is for them to participate in only 1 sport from an early age and to play it year-round. However, emerging evidence to the contrary indicates that efforts to specialize in 1 sport may reduce opportunities for all children to participate in a diverse year-round sports season and can lead to lost development of lifetime sports skills. Early sports specialization may also reduce motor skill development and ongoing participation in games and sports as a lifestyle choice. The purpose of this review is to employ the current literature to provide evidence-based alternative strategies that may help to optimize opportunities for all aspiring young athletes to maximize their health, fitness, and sports performance.

Evidence Acquisition:

Nonsystematic review with critical appraisal of existing literature.

Study Design:

Clinical review.

Level of Evidence:

Level 4.

Conclusion:

Based on the current evidence, parents and educators should help provide opportunities for free unstructured play to improve motor skill development and youth should be encouraged to participate in a variety of sports during their growing years to influence the development of diverse motor skills. For those children who do choose to specialize in a single sport, periods of intense training and specialized sport activities should be closely monitored for indicators of burnout, overuse injury, or potential decrements in performance due to overtraining. Last, the evidence indicates that all youth should be involved in periodized strength and conditioning (eg, integrative neuromuscular training) to help them prepare for the demands of competitive sport participation, and youth who specialize in a single sport should plan periods of isolated and focused integrative neuromuscular training to enhance diverse motor skill development and reduce injury risk factors.

Strength of Recommendation Taxonomy (SORT):

B.

Citius, Altius, Fortius: beneficial effects of resistance training for young athletes: Narrative review

The motto of the Olympic Games is Citius, Altius, Fortius which is Latin for 'Faster, Higher, Stronger'. It is a clarion call to all competitors, including the youngest, to engage in training strategies that prepare athletes to be the best in the world. Existing research indicates that various forms of resistance training can elicit performance improvements in young athletes. Stronger young athletes will be better prepared to learn complex movements, master sport tactics, and sustain the demands of training and competition. An integrative training programme grounded in resistance training and motor skill development can optimise a young athlete's potential to maximise their athletic and sporting performance, while reducing the risk of a sports-related injury. Resistance training may be especially important for modern-day young athletes who are more likely to specialise in one sport at an early age at the expense of enhancing general physical fitness and learning diversified sport skills. Structured interventions that include qualified instruction; targeted movement practice; and strength and conditioning activities that are developmentally appropriate, progressive and technique driven are needed to attain a level of athleticism that is consistent with the Olympic motto.

Training the developing brain part II: cognitive considerations for youth instruction and feedback

Growing numbers of youth participating in competitive, organized physical activity have led to a concern for the risk of sports-related injuries during important periods of human development. Recent studies have demonstrated the ability of integrative neuromuscular training (INT) to enhance athletic performance and reduce the risk of sports-related injuries in youth. Successful implementation of INT necessitates instruction from knowledgeable and qualified instructors who understand the unique physical, cognitive, and psychosocial characteristics of the youth to provide appropriate training instruction and feedback. Principles of a classical theory of cognitive development provide a useful context for discussion of developmentally appropriate methods and strategies for INT instruction of youth. INT programs that consider these developmentally appropriate approaches will provide a controlled efficacious environment for youth to improve athletic performance and reduce risk of sports-related injury, thus promoting a healthy active lifestyle beyond an individual's formative years.

The back squat: A proposed assessment of functional deficits and technical factors that limit performance

Fundamental movement competency is essential for participation in physical activity and for mitigating the risk of injury, which are both key elements of health throughout life. The squat movement pattern is arguably one of the most primal and critical fundamental movements necessary to improve sport performance, to reduce injury risk and to support lifelong physical activity. Based on current evidence, this first (1 of 2) report deconstructs the technical performance of the back squat as a foundation training exercise and presents a novel dynamic screening tool that incorporates identification techniques for functional deficits that limit squat performance and injury resilience. The follow-up report will outline targeted corrective methodology for each of the functional deficits presented in the assessment tool.

Train the Brain: Novel Electroencephalography Data Indicate Links between Motor Learning and Brain Adaptations

EEG differences were examined between part and whole practice in the learning of a novel motor task. Recording was done at 4 sites (i.e., O1, O2, C3, and C4) on 30 participants who performed a novel mirror star tracer task. Individuals were randomly assigned to 3 groups: whole practice, part practice, and control (no practice). Whole practice is defined as practicing a skill in its entirety. Part practice is defined as practicing separate, independent parts of the skill, and gradually combining those parts with parts that are dependent on one another. Each group was assessed during a pretest and posttest. EEG data was analyzed using a 2×2×2×3 (trials×hemisphere×site×practice) repeated measures mixed model ANOVA for each of the wave bands (lower alpha, upper alpha, lower beta, upper beta). All participants performed the task faster as no practice effect was found across the three groups; however the part practice group exhibited a significant decrease in errors. Reduced activation in the occipital and central sites was observed for lower alpha in the posttest compared to the pretest, for all participants. Hemispheric differences were present for all wavebands, with greater activation in the left hemisphere independent of practice type. The results of our study indicate that task learning was likely associated with the observed changes in the lower alpha waveband. Further, a concomitant behavior between the hemispheric lateralization of alpha and beta waveforms was observed. These results have implications for athlete training and rehabilitation. They indicate the utility of EEG for learning assessment in athletes. They also indicate learning strategies with a partial movement focus may be a beneficial strategy to support the development of complex sport skills training and rehabilitation strategies focused on reacquisition of skills prior to sport reintegration.