Reliability and validity of field-based fitness tests in youth soccer players

This study aimed to establish between-day reliability and validity of commonly used field-based fitness tests in youth soccer players of varied age and playing standards, and to discriminate between players without (“unidentified”) or with (“identified”) a direct route to professional football through their existing club pathway. Three-hundred-and-seventy-three Scottish youth soccer players (U11–U17) from three different playing standards (amateur, development, performance) completed a battery of commonly used generic field-based fitness tests (grip dynamometry, standing broad jump, countermovement vertical jump, 505 (505COD) and T-Drill (T-Test) change of direction and 10/20 m sprint tests) on two separate occasions within 7–14?days. The majority of field-based fitness tests selected within this study proved to be reliable measures of physical performance (ICC?=?0.83–0.97; p?p?2 (7)?=?101.646, p?相似文献   

A Coding System to Quantify Powerful Actions in Soccer Match Play: A Pilot Study

Purpose: The powerful activity profile of elite soccer match play has not been documented appropriately to inform specific maximal power assessment and development criteria. The aims of the current study were to develop a reliable soccer-specific powerful action (SSPA) notational analysis coding system that could be used to compare frequency and durations of powerful actions during elite youth soccer match play. Methods: Sixteen elite male English Premier League (EPL) Academy players (19 ± 1 yrs) were recorded by an individual camera during 16 competitive EPL U18 and U21 games. Video footage was analyzed using performance analysis software and SSPAs were coded according to the following categories: initial acceleration, leading acceleration, sprint, unilateral jump and bilateral jump. Results: The SSPA coding system demonstrated very good inter- and intra-rater reliability (kappa coefficients ≥ 0.827). Elite youth EPL soccer players undertook significantly more initial (31 ± 9) and leading (37 ± 12) accelerations than sprints (8 ± 3; p = .014, d = 1.7, and p < .001, d = 1.7, respectively) and jumps (6 ± 5; p = .002, d = 1.7 and p < .001, d = 1.7, respectively). Players performed a significantly greater number of initial and leading accelerations with action durations below 1.5 s compared to above 1.5 s (p = .001, d = 1.6, and p = .002, d = 1.4), respectively. Conclusions: Our SSPA coding system provides a reliable observational instrument for quantifying the frequency and duration of powerful actions performed during elite soccer match play. In our sample of elite youth soccer players, horizontal accelerations of short duration (< 1.5 s) from different starting speeds appear the most dominant powerful action in elite youth soccer match play.     

Optimising technical skills and physical loading in small-sided basketball games

Abstract

Differences in physiological, physical, and technical demands of small-sided basketball games related to the number of players, court size, and work-to-rest ratios are not well characterised. A controlled trial was conducted to compare the influence of number of players (2v2/4v4), court size (half/full court) and work-to-rest ratios (4x2.5 min/2x5 min) on the demands of small-sided games. Sixteen elite male and female junior players (aged 15–19 years) completed eight variations of a small-sided game in randomised order over a six-week period. Heart rate responses and rating of perceived exertion (RPE) were measured to assess the physiological load. Movement patterns and technical elements were assessed by video analysis. There were ～60% more technical elements in 2v2 and ～20% more in half court games. Heart rate (86 ± 4% & 83 ± 5% of maximum; mean ± SD) and RPE (8 ± 2 & 6 ± 2; scale 1–10) were moderately higher in 2v2 than 4v4 small-sided games, respectively. The 2v2 format elicited substantially more sprints (36 ±12%; mean ±90% confidence limits) and high intensity shuffling (75 ±17%) than 4v4. Full court games required substantially more jogging (9 ±6%) compared to half court games. Fewer players in small-sided basketball games substantially increases the technical, physiological and physical demands.     

对影响青少年运动员跳远踏板起跳准确性因素的探讨研究

在跳远比赛中,起跳是关键技术,踏板的准确性决定着运动员试跳的成绩,影响起跳的因素很多,其中踏跳的准确性是一个很重要的因素。据有关青少年比赛资料统计,在比赛中试跳犯规或不上板的情况占试跳次数的60%左右,还有运动员前三轮试跳失败而被淘汰,这说明在青少年的训练中,对助跑速度与踏板衔接准确性与稳定性的技术重视不够;为了提高青少年跳远训练的实效性,本文通过对我省青少年跳远运动员的助跑速度准确性的研究,来探研跳远运动员助跑踏跳的准确性。     

Space occupation near the basket shapes collective behaviours in youth basketball

This study aimed to analyse how youth basketball players explored numerical overloads during shot attempts by measuring their space occupation across specific court areas. Four process-tracing variables measured how the number of attackers (NA), number of defenders (ND), interpersonal distance between attacker and the closest defender (ID) and distance between attacker and the basket (DBkt) impacted on the performance outcome (converted shot; missed shot; ball possession lost). Ten competitive games involving 13 U14 teams were video recorded and players’ displacements were digitised. The associations between performance outcomes and the process-tracing measures were assessed using standardised mean differences and a cross-correlation function. A multinomial logistic regression was used to calculate the odds ratio (OR) for each of the three possible outcomes. Results revealed that when shot attempts occurred at larger ID and at smaller DBkt, the possibilities to obtain a converted shot increased. The numerical overload of defenders near the scoring target was predominantly associated with offensive success. Also, the possibility of attackers to lead the spatial relation of movements with the defenders, near the scoring target, appeared as a prominent strategy to succeed. In sum, basketball teams that exhibit potential to adapt their collective behaviours to local changes in the environment might be closer to achieving successful outcomes.     

Does self-determined motivation interact with environmental contexts to influence moderate-to-vigorous physical activity during a girls’ youth sport camp?

ABSTRACT

Objective: To explore whether basketball player’s self-determined motivation interacts with environmental contexts and coach training to influence percentage time in moderate-to-vigorous physical activity (%MVPA). Methods: A secondary analysis of data from 76 girls (mean ± SD, 10.5 ± 1.0 years) was conducted. Players were classified as high self-determined motivation (HSDM) or low self-determined motivation (LSDM) and randomised to trained (intervention) or untrained (control) coaches. Training included 2 workshops on strategies for activity-promoting practices. Girls were exposed to environmental contexts (practices and games) led by a trained/untrained coach (depending on arm) and one without coaches (free time) daily. Girls wore accelerometers each day. Using mixed random-effects models, the influence of motivation, context and training on %MVPA was analysed. Results: Trained coaches’ practices were associated with the greatest %MVPA with no difference between HSDM and LSDM players (38.28 ± 1.77%; 37.64 ± 1.80%; p = 0.66). HSDM players had significantly greater %MVPA versus LSDM players during untrained coaches’ practices (23.58 ± 1.77%; 20.51 ± 1.78%; p = 0.03). During games with trained coaches, HSDM players had greater %MVPA compared to LSDM players (23.79 ± 1.76%; 18.56 ± 1.74%; p < 0.001). No between-group difference in %MVPA during free time was found (12.85 ± 0.82%; 13.39 ± 0.84%; p = 0.64). Conclusion: The impact of individual differences in self-determined motivation on %MVPA during practices was attenuated when coaches were trained to implement activity-promoting practices.     

Sport-specific biomechanical responses to an ACL injury prevention programme: A randomised controlled trial

Anterior cruciate ligament (ACL) injury prevention programmes have not been as successful at reducing injury rates in women’s basketball as in soccer. This randomised controlled trial (ClinicalTrials.gov #NCT02530333) compared biomechanical adaptations in basketball and soccer players during jump-landing activities after an ACL injury prevention programme. Eighty-seven athletes were cluster randomised into intervention (6-week programme) and control groups. Three-dimensional biomechanical analyses of drop vertical jump (DVJ), double- (SAG-DL) and single-leg (SAG-SL) sagittal, and double- (FRONT-DL) and single-leg (FRONT-SL) frontal plane jump landing tasks were tested before and after the intervention. Peak angles, excursions, and joint moments were analysed using two-way MANCOVAs of post-test scores while controlling for pre-test scores. During SAG-SL the basketball intervention group exhibited increased peak knee abduction angles (p = .004) and excursions (p = .003) compared to the basketball control group (p = .01) and soccer intervention group (p = .01). During FRONT-SL, the basketball intervention group exhibited greater knee flexion excursion after training than the control group (p = .01), but not the soccer intervention group (p = .11). Although women’s soccer players exhibit greater improvements in knee abduction kinematics than basketball players, these athletes largely exhibit similar biomechanical adaptations to ACL injury prevention programmes.     

Prediction of shot success for basketball free throws: Visual search strategy

Abstract

In ball games, players have to pay close attention to visual information in order to predict the movements of both the opponents and the ball. Previous studies have indicated that players primarily utilise cues concerning the ball and opponents' body motion. The information acquired must be effective for observing players to select the subsequent action. The present study evaluated the effects of changes in the video replay speed on the spatial visual search strategy and ability to predict free throw success. We compared eye movements made while observing a basketball free throw by novices and experienced basketball players. Correct response rates were close to chance (50%) at all video speeds for the novices. The correct response rate of experienced players was significantly above chance (and significantly above that of the novices) at the normal speed, but was not different from chance at both slow and fast speeds. Experienced players gazed more on the lower part of the player's body when viewing a normal speed video than the novices. The players likely detected critical visual information to predict shot success by properly moving their gaze according to the shooter's movements. This pattern did not change when the video speed was decreased, but changed when it was increased. These findings suggest that temporal information is important for predicting action outcomes and that such outcomes are sensitive to video speed.     

Biomechanical mechanisms of jumping performance in youth elite female soccer players

ABSTRACT

We aimed to determine key biomechanical parameters explaining age-related jumping performance differences in youth elite female soccer players. Multiple biomechanical parameters from countermovement (CMJ) squat (SJ) and drop (DJ) jump testing of elite female soccer players (n = 60) within the same national training centre were analysed across ages 9-11y, 12-14y and 15-19y. Effects of age group and jump type on jump height were found, with the older jumping higher than the younger groups in all jumps (P < 0.05). For DJ, higher reactive strength index was found for older, compared to each younger group (P < 0.001). For CMJ and SJ, peak power was the most decisive characteristic, with significant differences between each group for absolute peak power (P < 0.0001) and body-weight-normalised peak power in CMJ (57 ± 7W/kg, 50 ± 7W/kg, 44.7 ± 5.5W/kg; P < 0.05) and between the older and each younger group in SJ (56.7 ± 7.1W/kg, 48.9 ± 7.1W/kg, 44.6 ± 6W/kg; P < 0.01). Age-related differences in jumping performance in youth elite female soccer players appear to be due to power production during standing jumps and by the ability to jump with shorter ground contact times during reactive jumps.     

浅谈篮球意识的培养

通过分析篮球比赛失利的原因,意识到篮球意识在篮球教学比赛实践中的重要性,提出培养队员篮球意识的途径及培养篮球意识应注意的问题。     

Anthropometric,physiological and maturational characteristics in selected elite and non-elite male adolescent basketball players

Abstract

We investigated the anthropometric, physiological and maturation characteristics of young players (13–14 years old) associated with being successful in basketball. Body parameters were measured (stature, total body mass, skinfolds and lengths) and physiological capacities were assessed by endurance, sprint (20 m), jump and dribbling tests. Chronological age (CA) was recorded and maturity estimated using predicted age at peak height velocity (APHV). Anthropometric analysis indicated that elite players were taller, heavier and had a higher percentage of muscle. Further, physiological testing showed that these elite players perform better in jump, endurance, speed and agility tests (especially in the agility and ball tests). In addition, these skills are correlated with point average during the regular season. More basketball players born in the first semester of the year are selected and there is a predominance of early-maturing boys among those selected for the elite team. Those who are more mature have advantages in anthropometric characteristics and physiological test results. In conclusion, around puberty, physical and physiological parameters associated with maturity and CA are important in determining the success of basketball players. These findings should be taken into account by trainers and coaches, to avoid artificial bias in their selection choices.     

Plasticity of human handedness: Decreased one-hand bias and inter-manual performance asymmetry in expert basketball players

Abstract

Athletes frequently have to adapt their skills to fast changes of play, often requiring the flexible execution of a particular movement skill with either hand. To assess the influence of sport-specific expertise and extensive sport training on human laterality, a video analysis of regular basketball games was performed for professional, semi-professional, and amateur players to investigate how non-dominant hand use and proficiency change with increasing expertise. Our results showed that the right-hand (i.e. dominant hand) bias in basketball players is reduced with increasing expertise (i.e. competitive level). Accordingly, we found that professional players use their non-dominant hand more often and with greater success than semi-professional and amateur players. This was true for most of the basketball-specific skills. Based on these results, we assume that increasing amounts of bilateral practice can lead to a shift in task-specific manual preference towards a higher use of both hands in competition, as well as to a higher proficiency for non-dominant hand actions in particular. From an applied perspective, the more frequent use and higher proficiency of the non-dominant hand in professional basketball players, compared with amateurs, suggests that the context-specific and skilled use of the non-dominant hand is crucial for successful play at higher competitive levels in the sport of basketball.     

The effects of plyometric jump training on physical fitness attributes in basketball players: A meta-analysis

BackgroundThere is a growing body of experimental evidence examining the effects of plyometric jump training (PJT) on physical fitness attributes in basketball players; however, this evidence has not yet been comprehensively and systematically aggregated. Therefore, our objective was to meta-analyze the effects of PJT on physical fitness attributes in basketball players, in comparison to a control condition.MethodsA systematic literature search was conducted in the databases PubMed, Web of Science, and Scopus, up to July 2020. Peer-reviewed controlled trials with baseline and follow-up measurements investigating the effects of PJT on physical fitness attributes (muscle power, i.e., jumping performance, linear sprint speed, change-of-direction speed, balance, and muscle strength) in basketball players, with no restrictions on their playing level, sex, or age. Hedge's g effect sizes (ES) were calculated for physical fitness variables. Using a random-effects model, potential sources of heterogeneity were selected, including subgroup analyses (age, sex, body mass, and height) and single training factor analysis (program duration, training frequency, and total number of training sessions). Computation of meta-regression was also performed.ResultsThirty-two studies were included, involving 818 total basketball players. Significant (p < 0.05) small-to-large effects of PJT were evident on vertical jump power (ES = 0.45), countermovement jump height with (ES = 1.24) and without arm swing (ES = 0.88), squat jump height (ES = 0.80), drop jump height (ES = 0.53), horizontal jump distance (ES = 0.65), linear sprint time across distances ≤10 m (ES = 1.67) and >10 m (ES = 0.92), change-of-direction performance time across distances ≤40 m (ES = 1.15) and >40 m (ES = 1.02), dynamic (ES = 1.16) and static balance (ES = 1.48), and maximal strength (ES = 0.57). The meta-regression revealed that training duration, training frequency, and total number of sessions completed did not predict the effects of PJT on physical fitness attributes. Subgroup analysis indicated greater improvements in older compared to younger players in horizontal jump distance (>17.15 years, ES = 2.11; ≤17.15 years, ES = 0.10; p < 0.001), linear sprint time >10 m (>16.3 years, ES = 1.83; ≤16.3 years, ES = 0.36; p = 0.010), and change-of-direction performance time ≤40 m (>16.3 years, ES = 1.65; ≤16.3 years, ES = 0.75; p = 0.005). Greater increases in horizontal jump distance were apparent with >2 compared with ≤2 weekly PJT sessions (ES = 2.12 and ES = 0.39, respectively; p < 0.001).ConclusionData from 32 studies (28 of which demonstrate moderate-to-high methodological quality) indicate PJT improves muscle power, linear sprint speed, change-of-direction speed, balance, and muscle strength in basketball players independent of sex, age, or PJT program variables. However, the beneficial effects of PJT as measured by horizontal jump distance, linear sprint time >10 m, and change-of-direction performance time ≤40 m, appear to be more evident among older basketball players.     

The relationship between functional potential and field performance in elite female wheelchair basketball players

The functional classification system for wheelchair basketball is based on an analysis of the players' functional resources through field-testing and game observation. Under this system, players are assigned a score of 1 to 4.5. The aim of this study was to determine if the wheelchair basketball player classification system reflects the existing differences in performance of elite female players. During the World Championship for Wheelchair Basketball in Sydney 1998, eight teams were videotaped for three 40-min games for a total of 120?min per team. Fifty-nine female players (Class I [1 and 1.5 points] n?=?12; Class II [2 and 2.5 points] n?=?20; Class III [3 and 3.5 points] n?=?13; Class IV [4 and 4.5 points] n?=?14) were retained for a detailed performance analysis by means of the Comprehensive Basketball Grading System (CBGS). Two-way analysis of variance showed high point players to perform better compared with low point players for the majority of variables determining the quality of game performance. A lack of significant differences between two adjacent classes was explained on the basis of the methodological approach, the class–position relationship in this sample, and the performance level of women's wheelchair basketball. We conclude that the performance of elite female wheelchair basketball players is dependent on functional ability.     

Short-term optimal load training vs a modified complex training in semi-professional basketball players

This study investigated the effects on neuromuscular performance of a 6-week Optimal Load Training (OLT) and a novel modified Complex Training (MCT) (complex pairs: the same exercise using a moderate and an OL) in basketball players, in-season. Eighteen male athletes were randomly assigned to one of the protocols. Anthropometric measurements were taken to evaluate body composition. Lower- and upper-body maximum dynamic strength, countermovement jump (CMJ), standing long jump (SLJ), 10-m sprint and change of direction (COD) were also assessed. Moderate-to-large strength gains (presented as percentage change ± 90% confidence limits) were obtained for half-squat (OLT: 10.8 ± 5.3%; MCT: 17.2 ± 11.6%) and hip thrust (OLT: 23.5 ± 17.7%; MCT: 28.2 ± 19.0%). OLT athletes achieved likely small improvements in sprint (1.6 ± 1.6%) and COD (3.0 ± 3.2%). Players in the MCT attained likely moderate improvements in COD (3.0 ± 2.0%) and possibly small in SLJ (2.5 ± 4.6%). No protocol relevantly affected CMJ or body composition. An ANCOVA test revealed unclear between-group differences. In conclusion, both protocols increased basketball players’ strength without the use of heavy loads (> 85% 1RM) and without impairing sprint, CMJ and SLJ performance. These findings suggest that basketball strength and conditioning professionals may use either method to counteract strength losses during the season.     

Functional capacities and sport-specific skills of 14- to 15-year-old male basketball players: Size and maturity effects

Abstract

The aim of the study was to estimate the influence of body size and pubertal status on variation in functional capacities and sport-specific skills of 59 youth basketball players aged 14.0–15.9 years. Height and mass were measured and stage of pubic hair was assessed at clinical examination. Six tests of functional capacity were evaluated: squat jump, countermovement jump, 60-s sit-ups, 2-kg standing medicine ball throw, hand grip strength, and 20-m multi-stage shuttle run. Four basketball skills were tested (shooting, passing, dribbling, and defensive movements). Comparisons between basketball players of different sexual maturity status were performed using analysis of covariance (controlling for chronological age). Functional capacities and basketball skills appeared to be largely independent of pubertal status especially after controlling for variation in body size. Results of multiple linear regressions indicated chronological age as a significant predictor for four items, while maturity status was a significant predictor for only one item. The influence of body mass was negative for two functional indicators (jumping, multi-stage shuttle run) and two basketball skills (dribbling, defensive movements), but positive for two functional tests of upper body strength (hand grip, ball throw). Height was positively correlated with two specific skills (passing, defensive movements), while a combination of tallness and heaviness was associated with a disadvantage on three functional capacities and two sport-specific skills.     

Decrements in knee extensor and flexor strength are associated with performance fatigue during simulated basketball game-play in adolescent,male players

This study quantified lower-limb strength decrements and assessed the relationships between strength decrements and performance fatigue during simulated basketball. Ten adolescent, male basketball players completed a circuit-based, basketball simulation. Sprint and jump performance were assessed during each circuit, with knee flexion and extension peak concentric torques measured at baseline, half-time, and full-time. Decrement scores were calculated for all measures. Mean knee flexor strength decrement was significantly (P < 0.05) related to sprint fatigue in the first half (R = 0.65), with dominant knee flexor strength (R = 0.67) and dominant flexor:extensor strength ratio (R = 0.77) decrement significantly (P < 0.05) associated with sprint decrement across the entire game. Mean knee extensor strength (R = 0.71), dominant knee flexor strength (R = 0.80), non-dominant knee flexor strength (R = 0.75), mean knee flexor strength (R = 0.81), non-dominant flexor:extensor strength ratio (R = 0.71), and mean flexor:extensor strength ratio (R = 0.70) decrement measures significantly (P < 0.05) influenced jump fatigue during the entire game. Lower-limb strength decrements may exert an important influence on performance fatigue during basketball activity in adolescent, male players. Consequently, training plans should aim to mitigate lower-limb fatigue to optimise sprint and jump performance during game-play.     

Association of different types of playing surfaces with bone mass in growing girls

The aim of this cross-sectional study was to compare bone mass in young female athletes playing ball games on different types of playing surfaces. About 120 girls, 9–13 years of age (10.6 ± 1.5 years old Tanner I–III) were recruited and divided into prepubertal and pubertal groups. The sample represented 3 groups of athletes: soccer (N = 40), basketball (N = 40), and handball (N = 40); and 6 different playing surfaces (soccer – ground, soccer – artificial turf, basketball – synthetic, basketball – parquet, handball – synthetic, and handball – smooth concrete). Total and regional body composition (bone mass, fat mass, and lean mass) were measured by dual-energy X-ray absorptiometry (DXA). The mechanical properties of the surfaces (force reduction, vertical deformation, and energy return) were measured with the Advanced Artificial Athlete (Triple A) method. The degree of sexual development was determined using Tanner test. The pubertal group showed that soccer players on the ground, basketball players on synthetic, and handball players on smooth concrete had higher values of bone mineral content (BMC) and bone mineral density (BMD) (P < 0.05) than the soccer players on the artificial turf, basketball players on parquet, and handball players on synthetic. In conclusion, a hard playing surface, with less vertical deformation and force reduction, and greater energy return, is associated with higher levels of BMD and BMC in growing girls, regardless of the sport they practice.     

第12届全运会辽宁青年女篮技术统计分析

采用文献资料法、录像观察法和数理统计法,对辽宁青年女篮在第12届全运会上的6场比赛的过程和攻防技术指标进行统计分析,旨在正视辽宁青年女篮的现状,找出其优势和不足,并针对问题提出建议。