Under-17 Research Articles

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

ABSTRACT 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.

Match injuries in English schoolboy rugby union

ObjectiveThis study describes the incidence, severity and burden of match injuries in schoolboy rugby union in England, across three age groups: under-13 (U13), under-15 (U15) and under-18 (U18).MethodsData regarding 574...

The Effect of Integrative Training Program on Youth Soccer Players’ Power Indexes

Integrative neuromuscular training (INT) is commonly employed for preventing injuries, yet there is a scarcity of studies examining its impact on the physical capabilities of young athletes. This study sought to explore the influence of a brief, in-season INT intervention on the performance of adolescent soccer players. The participants included thirty-one U15 (under 15 years old) soccer players who were randomly assigned to either the control group (CG) (engaged solely in soccer training, n = 14, 14.6 ± 0.6 years) or the exercise group (EG) (where INT was incorporated into traditional soccer training, n = 17, 14.1 ± 0.6 years). Early or late maturers were excluded from the study. The INT program lasted for 5 weeks (two sessions per week) and mainly included single-leg exercises. At the commencement and conclusion of the intervention program, measurements were taken for acceleration (10 m), speed (30 m), jumping ability (squat jump, SJ, and countermovement jump, CMJ), and change of direction ability (COD) (Illinois agility test). The data analysis employed a two-way repeated-measures ANOVA. The INT program resulted in enhanced performance for the EG in SJ (28.4–32.3, p &lt; 0.001, η2 = 0.463), CMJ (30.6–35.3, p &lt; 0.001, η2 = 0.426), and COD ability (18.11–17.64, p = 0.003, η2 = 0.545). No changes in performance were observed in the CG. The results suggest that the addition of a short-duration in-season INT program in U15 soccer players can induce positive adaptations in their performance.

Description of the Collective Behavior in Competition of Young Soccer Players Under-16 (U-16), Under-17 (U-17), Under-19 (U-19), and Under-23 (U-23), Considering the Areas of the Pitch and Phases of the Game.

Nieto, S, Echeazarra, I, Errekagorri, I, and Castellano, J. Description of the collective behavior in competition of young soccer players under-16 (U-16), under-17 (U-17), under-19 (U-19), and under-23 (U-23), considering the areas of the pitch and phases of the game. J Strength Cond Res 38(4): 714-723, 2024-The objective was to employ an integrated observational-notational record to describe collective behavior (CB) in competition matches of young soccer players from 4 teams, U-16, U-17, U-19, and U-23, playing for a professional soccer club academy. A total of 1,481 possessions were registered. Collective behavior, captured by GPS devices, was described with the variables: depth, surface area, stretch index, length, and width. In addition, from the notational analysis, the behavior depending on the area of the field (Z1, Z2, Z3, and Z4) and ball possession (POS), nonball possession (nPOS), and set pieces phases were contextualized. A 2-tailed analysis of variance was applied to compare the CB of the teams. Results show that: (a) in all ages/categories, CB varied significantly in and without the possession of the ball and was conditioned by the area of the pitch where the ball was; (b) CB showed higher values with the ball and greater variability without it; and (c) depending on the age, CB presented differences with larger effect sizes in depth and length, in and without the possession of the ball, in Z1 and Z2. Integrating positional data to the moment of play and areas of the field could help a more accurate analysis of the competition to better understand the CB evolution of young soccer players.

Head Acceleration Events in Male Community Rugby Players: An Observational Cohort Study across Four Playing Grades, from Under-13 to Senior Men

ObjectivesThe aim of this study was to examine the cumulative head acceleration event (HAE) exposure in male rugby players from the Under-13 (U13) to senior club level over 4 weeks of matches and training during the 2021 community rugby season.MethodsThis prospective, observational cohort study involved 328 male rugby players. Players were representative of four playing grades: U13 (N = 60, age 12.5 ± 0.6 years), U15 (N = 100, age 14.8 ± 0.9 years), U19 (N = 78, age 16.9 ± 0.7 years) and Premier senior men (N = 97, age 22.5 ± 3.1 years). HAE exposure was tracked across 48 matches and 113 training sessions. HAEs were recorded using boil-and-bite instrumented mouthguards (iMGs). The study assessed the incidence and prevalence of HAEs by ages, playing positions, and session types (match or training).ResultsFor all age grades, weekly match HAE incidence was highest at lower magnitudes (10–29 g). Proportionally, younger players experienced higher weekly incidence rates during training. The U19 players had 1.36 times the risk of high-magnitude (> 30 g) events during matches, while the U13 players had the lowest risk compared with all other grades. Tackles and rucks accounted for the largest HAE burden during matches, with forwards having 1.67 times the risk of > 30 g HAEs in rucks compared with backs.ConclusionsThis study provides novel data on head accelerations during rugby matches and training. The findings have important implications for identifying populations at greatest risk of high cumulative and acute head acceleration. Findings may guide training load management and teaching of skill execution in high-risk activities, particularly for younger players who may be exposed to proportionally more contact during training and for older players during matches.

The Body Composition Effects on Physical Tests and On-Court Game Performance of U-14 Elite Portuguese Basketball Players

The purpose of this study was to clarify the effect of body composition, particularly body fat percentage (BF%) and fat-free mass (FFM), on physical fitness and players’ on-court performance in U-14 elite Portuguese basketball players. A total of 166 male basketball players (age, 13.80 ± 0.38 years) and 131 female basketball players (age, 13.57 ± 0.55 years) from under-14 (U-14) elite regional teams were evaluated. Differences between body composition groups, regarding physical tests and performance-related variables, adjusted for years at age peak velocity (YAPHV), were evaluated using ANCOVA tests, for male and female players. Results showed that: (i) low body fat male players jumped significantly higher and had more relative jumping power, were faster, and had better game performance than higher body fat male players, (ii) higher fat-free mass male players revealed significantly higher upper body strength and gained more rebounds than other players, (iii) higher body fat female players threw the medicinal ball further than other female players, and (iv) higher fat-free mass female players had significantly more upper body strength and jumped significantly lower than low fat-free mass female players. In conclusion, BF% seems to be oppositely associated with physical fitness and on-court performance in male basketball players, and FFM seems to be related to upper body strength in both sexes. Coaches should promote interventions that target lower BF% and ideal FFM mass values to improve physical and on-court performance in youth basketball.

Self-Refereeing System in Ultimate during the Joint Junior Ultimate Championship in Three Different Divisions—A Different Way to Promote Fair-Play?

In ultimate games governed by the World Flying Disc Federation (WFDF), all competitors also take on the role of referee. The players discuss disputed calls with each other during the game, and then follow rules designed for these situations to determine how the play continues. The number one rule of the sport is to respect the spirit of the game (SOTG), which encourages competitive play while preserving mutual respect and minimizing the risk of injury. The use of SOTG in ultimate in the framework of self-arbitration as a moral practice aligns well with other tools of critical pedagogy. For this study, the SOTG scores of the WFDF Joint Junior Ultimate Championship (JJUC 2022) were analyzed. A total of 1009 players from 19 countries competed in 434 self-refereed games (29 national teams in the WJUC Under-20 (U20) tournament and 20 teams in the EYUC Under-17 (U17) tournament). All the scores from the individual criteria correlated well with the overall scores, but for the most part, they did not correlate with each other. Our experience with the scoring system has highlighted the importance of participants understanding the meaning of the results and how they may lead to a constructive reflection to improve exceptions, including scores representing fouls and rules knowledge. The findings provide important information for physical education teachers, coaches, and sport consultants and may be of use to design SOTG programs that could foster the experience of sportsmanship and to facilitate the ethical conduct of athletes in either recreative or in competitive contexts.

The incidence of anterior cruciate ligament injury in youth and male soccer athletes: an evaluation of 17,108 players over two consecutive seasons with an age-based sub-analysis.

To evaluate the incidence of anterior cruciate ligament (ACL) injuries in male athletes from professional soccer clubs over two consecutive seasons (2018-2019) with a sub-analysis based on age category: under-13 (U-13), under-15 (U-15), under-17 (U-17), and under-20 (U-20) years. A total of 17,108 young male soccer players were retrospectively reviewed from sixty-three professional clubs in the four highest Brazilian soccer divisions. Data regarding the number of athletes and the number of ACL injuries confirmed by magnetic resonance imaging (MRI) exams in the 2018 and 2019 seasons were collected. Incidence of ACL injury were compared by season, age category (under-13; under-15; under 17; and under-20), demographic region, and club division. Clubs from all regions of Brazil participated in the study. A total of 336 primary ACL injuries were diagnosed over the two seasons (8,167 athletes during the 2018 season and 8,941 athletes during the 2019 season) among all athletes, which corresponds to 2% of the included athletes. There were 11 cases (0.3%) in the under-13, 53 cases (1.3%) in the under-15, 107 cases (2.5%) in the under-17, and 165 cases (3.8%) in the under-20 age category. There was a higher incidence of ACL injury in the older age groups (p < 0.001). A total of 336 ACL injuries were identified in 17,108 youth soccer players from 63 professional clubs with an overall incidence of 2% over 2 seasons of competition. ACL injury rate ranged from 0.3% to 3.8% and was higher in the older and more competitive club divisions. IV.

Relationships between training load, peak height velocity, muscle soreness and fatigue status in elite-level young soccer players: a competition season study

BackgroundThis study aimed to compare training load parameters, delayed onset muscle soreness (DOMS), and fatigue status between season periods (1st and 2nd halves) in U14 soccer players and to analyze the relationships between training load parameters based on season periods (1st and 2nd halves) with peak height velocity (PHV), DOMS, and fatigue status in under-14 (U14) young elite soccer players. Additionally, it was intended to analyze if fatigue, DOMS and PHV could explain training load parameters across the season.MethodsTwenty U14 players that competed in the national league participated in this study. The players were monitored during the whole season (26 weeks), and evaluations were carried out at the end of the in-season. Anthropometric and body composition parameters and the maturity offset of each player were utilized to compute each player's age at PHV. Players reported their levels of DOMS and fatigue status using Hooper index questionnaires. The internal load was monitored using the rating of perceived exertion (RPE). Acute weekly internal load (AW), chronic weekly internal load (CW), acute: chronic workload ratio (ACWR), training monotony (TM), and training strain (TS) were also obtained.ResultsThe main results showed that TM was higher in the 2nd half, while CW, AW and DOMS were higher in the 1st half of the season. Moreover, the main correlations showed a positive correlation between PHV and TS (2nd half of the season) and between fatigue and TM (1st half of the season).ConclusionIn conclusion, variations in well-being status and PHV cannot explain the variations in internal training loads in elite U14 soccer players. In addition, internal training load indices during the first half of the competitive season can promote a fundamental base for progression loads during the second period of the competitive season.

Relative age effects in track-and-field: Identification and performance rebalancing.

Introduction: Relative Age Effect (RAE) consists of a biased distribution of the dates of birth in a same-age group. Objectives: This study aimed to investigate Relative Age Effect among French athletes in different track-and-field events, and propose a corrective adjustment method to highlight the true potential of an athlete with respect to his/her relative age. Methods: 358,610 performances from 2009 to 2019 of female and male athletes between 12 and 21years old were collected. Relative age distributions of performances were analyzed by level of competitiveness ("All," "Top50%," "Top10%" where "all" represents all athletes, top50% and top10% represent the best 50% and 10% of athletes per age category respectively) and age category, with chi-square and odd-ratio statistics. A linear relationship between distribution of performances and age leads to a calibration coefficient allowing to rebalance the performance by considering the effect of Relative Age Effect. Validation is obtained by Wilcoxon statistical test on actual athlete data. Results: Relative Age Effect is present in all types of events. It is larger when the level of competitiveness increases. In male 100m sprint, 1year difference between two athletes birth date represents an average gain of 931.01ms (6.5%) in the U13 (Under 13years old) and 229.65ms (1.9%) in the U17 (Under 17years old) categories. Our validated rebalancing methods allows to compensate for the biases induced by the relative age effect. By comparing the rebalanced performance and the realised performance of each athlete, we cannot say that they are significantly different. On average, there is no significant difference between these two performances. Conclusion: This study showed that there is a relative age effect among young French athletes, with an even greater effect as the level of competition increases. Thanks to the rebalancing method that has been validated, performances can now be better appreciated according to category and event.

Comparison among U-17, U-20, and Professional Female Soccer in the GPS Profiles during Brazilian Championships

The purpose of this study was to compare and characterize the physical demand of official matches among under-17 (U-17), under-20 (U-20), and professional (Pro) female soccer players. All matches were from the U-17, U-20, and Pro National Brazilian Championships. Fourteen Pro matches, nine U-20 matches, and four U-17 matches were analyzed. The external load was measured by the global positioning system (GPS) and the internal workload was assessed by the ratings of perceived exertion (RPE) multiplied by the duration of the match. The activity profiles measured were total distance covered (km), total sprint distance (m) (speed > 18 km·h-1), number of accelerations and decelerations (between 1 and 2 m·s-2 and >3 m·s-2), and top speed (km·h-1). For the analysis, we standardized all the metrics (except the top speed) by the time (in minutes) played. The Pro group presented higher sprint distances, number of accelerations and decelerations, and top speeds, compared to U-20 and U-17. There was no difference in the total distance among groups, and there was no difference in any GPS metrics between U-20 and U-17. The RPE was higher in Pro and U-17, compared to U-20; however, the workload-RPE was higher in Pro, compared to both U-17 and U-20 groups. These findings provide important information for the evolution of physical performance according to age categories in elite female soccer players.

Performance factors that negatively influence shooting efficiency in women's basketball.

The purpose of the present study was to examine the influence of selected factors (possession duration, game quarter, defensive pressure, shooting distance from the basket, and heart rate level) on shooting efficiency on Under-19 (U19) and senior level of women's basketball competition (second division). The analysis procedures included five U19 and six senior-level games, containing 224 and 252 shooting attempts, respectively. Binary logistic regression identified the opponent's defensive pressure and shooting distance from the basket as significant predictors of shooting efficiency in both categories. When defensive pressure was high, the chance for the missed shot was 3.5 (95% CI; 1.43-8.52) and 3.19 (95% CI; 1.4-7.26) times more likely than it was under the minimum defensive pressure for U19 and senior category, respectively. Shooting efficiency significantly decreased when the horizontal distance from the basket increased. In U19, a chance for a missed shot was 4.63 (95% CI; 2-10.712) and 5.15 (95% CI; 1.91-13.86) times higher for medium and long-distance (respectively), compared to short-range shooting. In the senior category, the chance for the missed shot was 3.9 (95% CI; 1.83-8.31) and 3.27 (95% CI; 1.43-7.52) times higher for medium and long-distance (respectively) when compared to a short distance. The possession duration, game quarter, and heart rate level were identified as insignificant predictors. Therefore, the aforementioned findings suggest that basketball players and coaches may benefit from designing training sessions where the defender puts pressure on the shooting player as in a real game situation and balanced the frequency of shooting from different distances from the basket.

Ankle Joint Dorsiflexion Reference Values in Non-Injured Youth Federated Basketball Players: A Cross-Sectional Study.

(1) Background: The aim of the present study was to establish ankle joint dorsiflexion reference values among youth federated basketball players. (2) Methods: Cross-sectional study. The participants were basketball players who belonged to youth basketball developmental teams (female and male) from under-12 (U12) to under-17 (U17) categories. Ankle joint dorsiflexion range of motion was evaluated with the weight-bearing lunge test through the Leg Motion system. The distance achieved was recorded in centimeters. (3) Results: 693 basketball players who met the eligibility criteria and volunteered to participate were included in the study. The mean (SD) of ankle joint dorsiflexion was 10.68 (2.44) cm and the reference values were: excessive hypomobility < 6.09 (0.54) cm; hypomobility 6.09 (0.88) cm–8.43 (0.77) cm; normal 8.44 (0.77)–13.11 (0.79) cm; hypermobility 13.11 (0.74)–15.44 (0.86) cm; and excessive hypermobility >15.44 (0.86) cm. (4) Conclusions: This study provides ankle joint dorsiflexion reference values in youth basketball players from 12 to under 17 years old.

A randomized open-labeled study to examine the effects of creatine monohydrate and combined training on jump and scoring performance in young basketball players.

ABSTRACTBackgroundCreatine monohydrate (CrM) supplementation has been shown to be an effective and safe nutritional supplement to improve performance; however, the impact of CrM supplementation in young basketball players is less clear. This study evaluated the effects of CrM supplementation during a strength and conditioning training (SCT) program on lower-limb strength parameters and performance in under-16 (U16) basketball players.MethodsTwenty-three male U16 basketball players participated in this study (14.3 ± 0.4 years; BMI: 20.7 ± 2.2 kg∙m−2). The players were randomly assigned to either a CrM group (n = 12) that ingested 0.1 g·kg−1·day−1 of CrM or to a non-supplemented control group (n = 11, CON). The athletes participated in an 8-week SCT program consisting of two lower-limb resistance-training sessions and two plyometric sessions per week. Squat jump (SJ), drop jump (DP), countermovement jump (CMJ), and Abalakov (ABK) jump power tests as well as basketball performance (points and minutes per game) were measured before, during and/or after the intervention. Data were analyzed using a general linear model with repeated measures with independent Student’s t-test pairwise comparisons.ResultsThe results (95% confidence interval for mean change from baseline) show that there were significant differences for all variables for CrM and CON, respectively: SJ (cm): 2.6 – 6.4, P < 0.01 and 2.2–5.1 P < 0.01; DJ (cm): 2.5–5.6, P < 0.01, and 1.8–4.4, P < 0.01; CMJ (cm): 0.3–0.8, P < 0.01, and 0.2–0.5, P < 0.01; ABK (cm): 2.8–5.5, P < 0.01 and 0.7–2.6, P = 0.003. A significant group x time interaction (p = 0.003, ηp2 = 0.342) was observed in ABK performance. No significant group x time effects were seen in squat jump (p = 0.449, ηp2 = 0.028), drop jump (p = 0.143, ηp2 = 0.099), or counter movement jump (p = 0.304, ηp2 = 0.05). A significant interaction effect was also observed in points per game (p = 0.049, ηp2 = 0.149), while a non-significant but medium effect was seen in minutes per game (p = 0.166, ηp2 = 0.094).ConclusionsCrM supplementation in conjunction with resistance and plyometric training increased the lower-limb ABK power and scoring performance in U16 basketball players.

Training Load, Maturity Timing and Future National Team Selection in National Youth Basketball Players.

Despite its importance to the management of training stress, monotony and recovery from exercise, training load has not been quantified during periods of intensity training in youths. This study aimed to (1) examine and quantify the training load (TL) in youth national team basketball players during a 2-week training camp according to maturity timing and (2) determine which parameters were related to under-18 (U18) national team selection. Twenty-nine U-16 national team basketball players underwent an anthropometric assessment to determine maturity timing. Players were categorised by maturity timing (early vs. average), whilst TL parameters during a 2-week training camp (i.e., 21 sessions) prior to FIBA U16 European Championship were used for group comparison and to predict future U-18 national team selection. The early-maturing players, who were taller and heavier (p < 0.05), experienced greater training strain in week 1 (p < 0.05) only. Irrespective of maturity timing, training loads in week 2 were predictive of onward selection for the U-18 national team. Conclusion: Based on present findings, practitioners are encouraged to develop their athletes’ ability to tolerate high weekly loads, but also to be mindful that athletes’ perceived exertion during national team training may be influenced by maturity timing.

Eight Weeks of Self-Resisted Neck Strength Training Improves Neck Strength in Age-Grade Rugby Union Players: A Pilot Randomized Controlled Trial.

Greater neck strength is associated with fewer head and neck injuries. Neck-strengthening programs are commonly burdensome, requiring specialist equipment or significant time commitment, which are barriers to implementation. Completing a neck-strengthening program will increase isometric neck strength in age-group rugby players. A pilot randomized controlled exercise intervention study. Level 2. Twenty-eight U18 (under 18) male regional age-group rugby union players were randomized (intervention n =15/control n = 13). An 8-week exercise program was supervised during preseason at the regional training center. Control players continued their "normal practice," which did not include neck-specific strengthening exercises. The 3-times weekly trainer-led intervention program involved a series of 15-second self-resisted contractions, where players pushed maximally against their own head, in forward, backward, left, and right directions. Peak isometric neck strength (force N) into neck flexion, extension, and left and right side flexion was measured using a handheld dynamometer. Postintervention between-group mean differences (MDs) in isometric neck strength change were adjusted for baseline strength and favored the intervention for total neck strength (effect size [ES] = 1.2, MD ± 95% CI = 155.9 ± 101.9 N, P = 0.004) and for neck strength into extension (ES = 1.0, MD ± 95% CI = 59.9 ± 45.4 N, P = 0.01), left side flexion (ES = 0.7, MD ± 95% CI = 27.5 ± 26.9 N, P = 0.05), and right side flexion (ES = 1.3, MD ± 95% CI = 50.5 ± 34.4 N, P = 0.006). This resource-efficient neck-strengthening program has few barriers to implementation and provides a clear benefit in U18 players' neck strength. While the present study focused on adolescent rugby players, the program may be appropriate across all sports where head and neck injuries are of concern and resources are limited. Greater neck strength is associated with fewer head and neck injuries, including concussion. Performing this neck exercise program independently, or as part of a whole-body program like Activate, an interactive guide for players and coaches, could contribute to lower sports-related head and neck injuries.

Effect of bio-banding on physiological and technical-tactical key performance indicators in youth elite soccer

ABSTRACT Bio-banding has been introduced to reduce the impact of inter-individual differences due to biological maturation among youth athletes. Existing studies in youth soccer have generally examined the pilot-testing application of bio-banding. This is the first study that investigated whether bio-banded (BB) versus chronological age (CA) competition affects reliable physiological and technical-tactical in-game key performance indicators (KPIs) using a randomized cross-over repeated measures design. Sixty-five youth elite soccer players from the under-13 (U13) and under-14 (U14) age category and with maturity offsets (MO) between −2.5 and 0.5 years, competed in both a BB and CA game. For statistical analysis, players were divided into four sub-groups according to CA and MO: U13MOlow (CA ≤ 12.7, MO ≤ −1.4), U13MOhigh (CA ≤ 12.7, MO > −1.4), U14MOlow (CA > 12.7, MO ≤ −1.4), U14MOhigh (CA > 12.7, MO > −1.4). The two-factor mixed ANOVA revealed significant (p < .05) interactions between competition format and sub-group for the KPIs high accelerations ( = .176), conquered balls ( = .227) and attack balls ( = .146). Especially, U13MOhigh (i.e. early maturing players) faced a higher physiological challenge by having more high accelerations (|d| = 0.6) in BB games. Notably, U14MOlow (i.e. late maturing players) had more opportunities to show their technical-tactical abilities during BB games with more conquered balls (|d| = 1.1) and attack balls (|d| = 1.6). Affected KPIs indicate new challenges and learning opportunities during BB competition depending on a player’s individual maturity status. Bio-banding can beneficially be applied to enhance the talent development of youth elite soccer players.

Effects of Combined Plyometric and Short Sprints Training on Athletic Performance of Male U19 Soccer Players.

This project investigated adding 8 weeks of biweekly plyometric and short sprints training into standard training in elite youth soccer players. An experimental group (EG, n = 18, age: 17.6 ± 0.6 years, body mass: 67.6 ± 5.8 kg, height: 1.75 ± 0.06 m, and body fat: 11.5 ± 1.6%) and control group (CG, n = 18, age: 17.5 ± 0.6 years, body mass: 68.8 ± 3.6 kg, height: 1.77 ± 0.04 m, and body fat: 11.7 ± 1.2%) participated. Pre-intervention and post-intervention measures were squat-jump (SJ), countermovement-jump (CMJ), standing long jump (SLJ), 5 and 20 m sprints, change-of-direction ability (4 × 5 m sprint test [S 4 × 5 m] and sprint 9-3-6-3-9 m with backward and forward running [SBF]), repeated change of direction (RCOD), and static balance (the stork balance test). For all parameters, significant (p < 0.001, > 0.10) time and interaction (group × time) effects were observed. For three parameters (SBF, RCOD fastest time, and SLJ) no significant group effects were observed. The EG consistently showed a significantly higher performance level than the CG and a higher amount of effect sizes d (EG: drange: 1.27–2.61; CG: drange: 0.13–0.79) as an indicator for the development of performance between pre-intervention and post-intervention measures. Adding biweekly plyometric and short sprint training to standard training improves the athletic performance of young soccer players. Such plyometric and short sprint training conditioning can be highly recommended as part of the annual short training program for male elite under-19 (U19) soccer players.

What Will We Do? The Action Plan From a Brazilian Professional Football Club Youth Academy Facing the COVID-19 Pandemic.

In 2020, the world was affected by the COVID-19 pandemic, which remains a major challenge for most countries today. In Brazil, football clubs' youth academies have faced a disruption of their regular activities. In order to study how the learning cultures of a Brazilian professional football club youth academy have been changed, and the alternatives created by the club's staff within this context, this perspective article aims to analyze how they have structured the Under-15 (U15) team learning culture during social isolation due to the COVID-19 pandemic. Through document and thematic analysis on a Brazilian professional football club's youth academy program, we promoted a dialogue between the process of adaptation to remote theoretical-tactical teaching with the learning theory proposed by Hodkinson and collaborators. The main theme of analysis of this study was the remote structure of the theoretical-tactical learning and physical training. Challenged with the need to transpose face-to-face activities into a learning culture based on remote communication, the U15 team coaching staff created a process to prescribe physical training, and to teach and discuss football tactical issues with young players during the period of social isolation. This perspective article shows that it is possible for sports institutions to create programs for the development of young athletes within the social isolation/distancing context, considering both theoretical-tactical learning and physical training processes. The adaptation to remote environments as structures for the learning culture seems a challenge, but is also a good alternative for young players to develop their interpretation and perception of football theoretical-tactical issues.

Hamstring and Quadriceps Muscle Strength in Youth to Senior Elite Soccer: A Cross-Sectional Study Including 125 Players.

Increasing age, high quadriceps strength, and low hamstring muscle strength are associated with hamstring strain injury in soccer. The authors investigated the age-related variation in maximal hamstring and quadriceps strength in male elite soccer players from under-13 (U-13) to the senior level. A total of 125 elite soccer players were included from a Danish professional soccer club and associated youth academy (first tier; U-13, n = 19; U-14, n = 16; U-15, n = 19; U-17, n = 24; U-19, n = 17; and senior, n = 30). Maximal voluntary isometric force was assessed for the hamstrings at 15° knee joint angle and for the quadriceps at 60° knee joint angle (0° = full extension) using an external-fixated handheld dynamometer. Hamstring-to-quadriceps strength (H:Q) ratio and hamstring and quadriceps maximal voluntary isometric force levels were compared across age groups (U-13 to senior). Senior players showed 18% to 26% lower H:Q ratio compared with all younger age groups (P ≤ .026). Specific H:Q ratios (mean [95% confidence interval]) were as follows: senior, 0.45 (0.42-0.48); U-19, 0.61 (0.55-0.66); U-17, 0.56 (0.51-0.60); U-15, 0.59 (0.54-0.64); U-14, 0.54 (0.50-0.59); and U-13, 0.57 (0.51-0.62). Hamstring strength increased from U-13 to U-19 with a significant drop from U-19 to the senior level (P = .048), whereas quadriceps strength increased gradually from U-13 to senior level. Elite senior soccer players demonstrate lower H:Q ratio compared with youth players, which is driven by lower hamstring strength at the senior level compared with the U-19 level combined with a higher quadriceps strength. This discrepancy in hamstring and quadriceps strength capacity may place senior-level players at increased risk of hamstring muscle strain injuries.