Relationship Between Anthropometric and Physiological Characteristics in Youth Soccer Players

Reliability and validity of a reactive agility test with soccer goalkeeper-specific movements for adolescents

BACKGROUND

There is a lack of objective measures and assessments of goalkeeping proficiency and performance in the literature. Furthermore, no reports have focused on adolescent goalkeepers (under the age of 15). The aim of this study was to determine the reliability and validity of the Goalkeeper Reactive Agility Test for Adolescents (GRATA).

METHODS

Content validity was assessed by seven experts and the Item-Content Validity Index (I-CVI) was calculated. We used similar settings to an agility test for college-aged goalkeepers, although the number of repetitions and running direction of the latter parts of the test were modified (number of repetitions: from 3 to 2; running direction: from forward to backward). Eighty-five adolescent male goalkeepers (age: 13.4 years) performed the test three times. The intraclass correlation coefficient (ICC) was used for relative reliability and the standard error of measurement (SEM) and the smallest worthwhile change (SWC) for absolute reliability.

RESULTS

The I-CVI was 0.86, above the acceptable level of 0.78. The mean running time of the GRATA was 11.98 s. The ICC value was 0.91 (P<0.01; 95% confidence interval [95% CI]: 0.87-0.94), the SEM 0.26 s and the SWC 0.17 s.

CONCLUSIONS

Our results demonstrate that the GRATA has sufficient reliability and content validity in adolescent GKs.

Effects of the Core Training Program on Functional Movement Screen, Skill Performance, Competitive State Anxiety, and Trait Sport-Confidence of College Football Players

OBJECTIVES The purpose of the present study was to investigate the effects of a core training program on functional movement screen, skill performance, competitive state anxiety, and trait sport confidence of college football players.METHODS College football players were divided into core training (<i>n</i>=25) and control (<i>n</i>=16) groups. Core training was conducted for a total of 12 weeks of 2 sessions per week with 50 minutes per session. Pre, mid (6 weeks), and post (12 weeks) tests measured functional movements, and skill performance such as dribbling, agility, speed, momentum and competitive state anxiety, trait sport-confidence. For analysis of study results, descriptive statistics, and two-way ANOVA with repeated measures were used.RESULTS The study results showed overall improvements for the core training group in functional movement test scores, skill performance, and competitive state anxiety, trait sport-confidence. In addition, the core training group also showed significant improvement in the total factors, except for hurdle step, and rotary stability.CONCLUSION In conclusion, data shows a core training program improves functional movement screen scores, skill performance, competitive state anxiety, and trait sport-confidence of college football players.

Body Composition Interactions with Physical Fitness: A Cross-Sectional Study in Youth Soccer Players

This study aimed to: (i) analyze fat mass and physical fitness variations among age-groups and playing positions, and (ii) explore the relationship between fat mass and physical fitness in youth male soccer players. A total of 66 players from under-16, under-17, and under-19 were tested. Body mass, skinfolds, countermovement jump (CMJ), single-leg triple hop jump (SLTH), bilateral triple hop jump (BTH), and yo-yo intermittent recovery Level 2 (YYIR-2) were assessed. A two- and one-way ANOVA were conducted, and the effect size was measured. Interactions were found in skin folds and fat mass. The under-19 group was taller, heavier, with a greater BMI and muscle mass than the under-16 group. They also exceeded the under-16 and under-17 in SLTH, BTH, and YYIRT-2. The under-17 group jumped higher and longer than under-16 group. Goalkeepers were taller and heavier than the midfielders. Central defenders were taller and had more muscle mass than midfielders and were heavier than the midfielders and wingers. The wingers jumped higher than the midfielders and showed better YYIRT-2. BMI was small correlated with YYIRT-2 and moderately with CMJ. Fat mass had a moderate negative correlation with CMJ and YYIRT-2. Muscle mass largely correlated with CMJ, UTH, very large with BTH and moderate with YYIRT-2. Summarily, with increasing age, better performances and body compositions were registered. Muscle mass better influences performance than body fat. Body composition can distinguish players positions.

The soccer goalkeeper profile: bibliographic review

OBJECTIVE

The main aim of this article was to review the existing scientific literature on the soccer goalkeeper.

METHOD

This article has reviewed the scientific literature related to the soccer goalkeeper as long as they offered specific information about this position on the field, including a total of 56 scientific articles.

RESULTS

The knowledge already recollected by authors to be able to apply it on training has been divided in the following chapters: anthropometric profile, conditional and performance profile (sprint, jump, agility, strength, aerobic capacity, mobility, and specific game technique), external load profile, and injury pathological profile.

CONCLUSION

The most noteworthy conclusions obtained are: 1) the higher the level of the team, the higher and heavier the goalkeepers; 2) in early ages (9-13 years) the training of goalkeepers is not well posed, since compared to the players are worse both in physical capacities and technique; 3) the aerobic capacity at long distances does not influence the performance of the goalkeeper; 4) the sprint, the jump, the agility, and the mobility are factors that determine the performance of the goalkeeper; 5) the goalkeepers are less likely to be injured than the field players, but there are certain typical injuries in the position that must be protected by a proper way of strengthening and technique.

Physical Fitness and Performance in Talented & Untalented Young Chinese Soccer Players

Sports performance is a complex process that involves many factors, including ethnic and racial differences. China's youth soccer is in a process of constant development, although information about the characteristics of its players and their methodological systems is scarce. The aim of this retrospective study was to characterize the physical fitness and the competitive performance of 722 Chinese players of three sports categories (8.0-9.9, 10.0-11.9 and 12.0-13.9 years), who were classified by their coaches as talented (n = 204) or untalented (n = 518). Players were assessed for anthropometry (body height, body mass, body mass index), lung capacity (Forced Vital Capacity), jumping performance (Squat Jump, Countermovement Jump and Abalakov tests), sprinting performance (10 m and 30 m Sprint tests), agility performance (Repeated Side-Step test) and flexibility (Sit & Reach test). A descriptive, comparative, correlational and multivariate analysis was performed. Competitive ranking was created in order to act as dependent variable in multiple linear regression analysis. Results indicate that Chinese players classified as talented have better motor performance than untalented ones. However, these differences are neither related nor determine the competitive performance of one group or the other.

Fluctuations of Training Load Variables in Elite Soccer Players U-14 throughout the Competition Season

Excessive daily training load (TL) can affect the musculoskeletal system health of youth elite soccer players. The purposes of this study were (i) to describe the TL and session rating of perceived exertion (s-RPE) throughout the competition season; (ii) to analyze the weekly (w) differences of acute (daily) workload (wAWL), chronic workload (wCWL), acute–chronic workload ratio, training monotony (wTM), and training strain (wTS) among three periods over the season (early-, mid-, and end-season) by playing position; and (iii) to compare the TL variables during competition periods for the whole team. Twenty young elite soccer players in the under-14 category participated in this study. The game positions were considered as six wide defenders and wide midfielders (WM), five central defenders and central midfielders, and four strikers (ST). Daily monitoring was continued for 26 weeks during a full competition season. According to the league schedule, the season was divided into three periods: early-season from w1 to w8, mid-season from w9 to w17, and end-season from w18 to w26. The main results were that the higher TLs were detected in the early- and mid-season. There was a wAWL and wCWL decrease for all playing positions from early- to mid- and end-season, but the wCWL change was significant only from early- to mid-season (p ≤ 0.05). For all playing positions but ST, there was a considerable wTM increase from early- to mid-season. When compared with all other playing positions in terms of wAWL and wCWL, WM showed significantly greater values (p ≤ 0.05). Throughout the season periods, all workload indicators showed a considerable reduction, although there was a significant increase in the three other workload-derived variables (all with p ≤ 0.05) and namely: (i) wACWLR from mid- to end-season; (ii) wTM from early- to mid- and end-season; and (iii) wTS from early- to mid-season. Daily training load and s-RPE had significant fluctuations during all macrocycles of the competition season (p ≤ 0.05). In addition, in the mid-season, wTM and wTS were higher. Training load monitoring (in terms of, e.g., wAWL, wCWL, and s-RPE) could be the key for coaches of soccer teams to prevent overtraining and injury, especially in U-14 players, who are more susceptible to being affected by high workload.

Assessment of diet quality and physical activity of soccer players aged 13 to 16, from the Principality of Asturias, Spain

INTRODUCTION

Diet and physical activity are factors that have key roles in childhood overweight and obesity prevention. Appropriate assessment of these factors is an essential task in public health.

OBJECTIVE

The main aims of the study are to assess body composition, physical activity, and adherence to Mediterranean diet of soccer players, aged 13 to 16 years old in Asturias, Spain. It also aims to evaluate the relationships between diet, physical activity, body composition, and personal characteristics.

METHODS

A cross-sectional descriptive survey approach was used involving children (n = 303) with a mean age of 14.15 years (SD = 1.06), and using the KIDMED and PAQ-A questionnaires to assess adherence to Mediterranean diet and level of physical activity, respectively. Body composition was represented using the participants' body mass index.

RESULTS

Approximately 23.1% of the participants were overweight or obese. With regards to adherence to Mediterranean diet, 54.8% of the participants had medium adherence, while 8.9% had low adherence. PAQ-A mean score was 2.69 (SD = 0.47). Excess weight was associated with being a goalkeeper (P = .001), higher PAQ-A (P = .011), and lower KIDMED scores (P = .032). Correlation analysis showed an inverse association between age and PAQ-A score (r = -0.122), and a direct association between KIDMED and PAQ-A scores (r = 0.152).

CONCLUSION

Participants had an adequate level of physical activity. However, they had an obesogenic profile similar to that of their age population, who were not soccer players. Actions to improve adherence to healthy diet practices are highly recommended.

Talent Identification in Youth Soccer: Prognosis of U17 Soccer Performance on the Basis of General Athleticism and Talent Promotion Interventions in Second-Grade Children

Several talent identification programs in elementary school have implemented motor diagnostics to introduce children to groups of sports, like game sports, or even to particular sports like soccer. However, as in most other sports, in youth soccer, the predictive value of such early testing is still unclear. This prospective study evaluated the midterm prognostic validity of generic motor performance tests. The sample consisted of male second-grade children, which had received a recommendation to participate in soccer. The talent screening campaign was a basic check comprising two anthropometric parameters, five physical fitness, and three motor competence diagnostics of the German Motor Test 6-18. The test data were collected from the participating elementary school classes of the years 2010 to 2014. The soccer competition performance of those children having completed the age of at least 15 years (n = 502) up to the end of the season 2019/2020 (2020, September 30) was recorded. This group of U17 players was then assigned individually to five different competition levels. The prognostic validity of the physical and physiological tests was determined using ANOVAs, odds ratios, and a regression path analysis. All diagnostic methods exhibited medium-to-high prognostic validity over the 8 year time span from the talent screening to the later soccer competitions in the adolescent age groups. For later success in soccer on the province level, the 6-min run (OR = 4.28), dynamic balance (OR = 4.04), and 20-m sprint (OR = 2.46), as well as the participation in the training center of the German Soccer Federation (OR = 5.67) and the diversity of club sport activities (OR = 3.56), were of particular importance.

Fluctuations in Well-Being Based on Position in Elite Young Soccer Players during a Full Season

The current study surveyed weekly and daily variations of well-being ratings relative to the Hooper Index (HI): fatigue (wFatigue), stress (wStress), delayed onset muscle soreness (wDOMS), and sleep quality (wSleep) during a soccer season based on players’ positions. The full-season was divided into three meso-cycles: Early season, week (W)1 to W7; Mid-season, W8 to W13, and End-season, W14 to W20. Twenty-six young players participated in the study (age, 15.5 ± 0.2 years; height, 172.9 ± 4.2 cm; body mass, 61.4 ± 5.6 kg; body fat, 8.6 ± 2.9%; VO_2max, 48.4 ± 2.4 mL.kg⁻¹·min⁻¹; maturity offset, 1.9 ± 0.3 years). Participants played in the same team and competed in Iran national under-16 competitions. Well-being status was monitored on training days using the HI questionnaire. The main result was a significant difference between well-being status 5 days before match day (MD) and 4 days before MD, compared to MD for all playing positions (p ≤ 0.001). The highest and lowest records occurred during End-season for wDOMS (strikers = 11.5 ± 8.4 arbitrary units (AU)), Early season (central defenders = 9.5 ± 0.7 AU) and for wFatigue (central midfielders = 11.4 ± 0.9 AU), and Early season (wide defenders = 9.7 ± 0.7 AU), respectively. Overall, the results showed a significant increase in wStress and wSleep for all players’ positions from Early- to End-season. The main application of this study is to make coaches aware of their players’ well-being fluctuations throughout the full season, especially in young elite soccer players, and to avoid injuries, overtraining, and overreaching as much as possible.

Vertical and Horizontal Asymmetries Are Related to Slower Sprinting and Jump Performance in Elite Youth Female Soccer Players

ABSTRACT

Bishop, C, Read, P, McCubbine, J, and Turner, A. Vertical and horizontal asymmetries are related to slower sprinting and jump performance in elite youth female soccer players. J Strength Cond Res 35(1): 56-63, 2021-Interlimb asymmetries have been shown to be greater during vertical jumping compared with horizontal jumping. Notable interlimb differences have also been established at an early age in male youth soccer players. Furthermore, given the multiplanar nature of soccer, establishing between-limb differences from multiple jump tests is warranted. At present, a paucity of data exists regarding asymmetries in youth female soccer players and their effects on physical performance. The aims of this study were to quantify interlimb asymmetries from unilateral jump tests and examine their effects on speed and jump performance. Nineteen elite youth female soccer players performed a single-leg countermovement jump (SLCMJ), single, triple, and crossover hops for distance, and a 20-m sprint test. Test reliability was good to excellent (intraclass correlation coefficient = 0.81-0.99) and variability acceptable (coefficient of variation = 1.74-5.42%). A 1-way analysis of variance highlighted larger asymmetries from the SLCMJ compared with all other jump tests (p < 0.05). Pearson's correlations portrayed significant relationships between vertical asymmetries from the SLCMJ and slower sprint times (r = 0.49-0.59). Significant negative relationships were also found between horizontal asymmetries during the triple hop test and horizontal jump performance (r = -0.47 to -0.58) and vertical asymmetries during the SLCMJ and vertical jump performance (r = -0.47 to -0.53). The results from this study highlight that the SLCMJ seems to be the most appropriate jump test for identifying between-limb differences with values ∼12% showing negative associations with sprint times. Furthermore, larger asymmetries are associated with reduced jump performance and would appear to be direction specific. Practitioners can use this information as normative data to be mindful of when quantifying interlimb asymmetries and assessing their potential impact on physical performance in youth female soccer players.

Examination of Physical Fitness Parameters Between Professional and Amateur Greek Soccer Players During the Transition Period

ABSTRACT

Bekris, E, Pidoulas, G, Pidoulas, P, Gissis, I, Katis, A, and Komsis, S. Examination of physical fitness parameters between professional and amateur Greek soccer players during the transition period. J Strength Cond Res 35(3): 776-781, 2021-The aim of the study was to compare physical fitness parameters between professional and amateur soccer players of different levels. The sample consisted of 381 soccer players divided in 4 experimental groups: first division professional players (n = 115), second division professional players (n = 70), third division semiprofessional players (n = 93), and amateur soccer players (n = 103). Players were tested for several physiological parameters at the end of the transition period. Analysis of variance showed significantly lower body fat and increased maximum oxygen consumption (V̇o2max) and velocity of maximum oxygen consumption (vV̇o2max) values for first division professional players compared with the other experimental groups (p < 0.05). Similarly, first division professional players showed higher performance during squat jump and countermovement jump test compared with the other experimental groups (p < 0.05). Significant differences on flexibility test were observed between amateur players and the other group (p < 0.05). The results of the study indicated that Greek soccer players at the highest level overcome in almost all the underexamination physiological parameters probably because of less absence from training and better implementation of training programs during the transition period.

The Relative Age Effect on Anthropometry, Body Composition, Biological Maturation and Motor Performance in Young Brazilian Soccer Players

The present study aimed to investigate the influence of months of birth on anthropometry, body composition, biological maturation, and motor performance in young Brazilian soccer players. Young Brazilian soccer players from the Under-13 (n = 50; 13.6 ± 0.3 years), Under-15 (n = 50; 15.5 ± 0.4 years), and Under-17 categories (n = 46; 17.7 ± 0.3 years) took part in this study. Athletes were divided according to chronological age, 1^st tertile (January to April); 2^nd tertile (May to August); and 3^rd tertile (September to December). Anthropometry, body composition, biological maturation, and motor performance variables were evaluated for all participants. There were no differences between the U-13, U-15, and U-17 categories regarding birth tertiles (p > 0.05). Differences between the ages and birth tertiles were observed for the stature, body mass, and lean body mass (p < 0.05). Moreover, differences were found in maturational status between the ages and birth tertiles (p < 0.05). In general, U-13 players showed lower values compared to U-15 and U-17 players in tests of motor performance. In addition, there was a difference in motor performance between the birth tertiles only for RSA variables. The months of birth influenced the stature, body mass, lean body mass, and repeated sprint ability in the U-13 and U-15 categories. Thus, care should be taken during the process of talent selection, as many young players could be underestimated due to their date of birth.

Associations of Body Composition, Maximum Strength, Power Characteristics with Sprinting, Jumping, and Intermittent Endurance Performance in Male Intercollegiate Soccer Players

The purpose of this study was to determine the relationships between body composition, strength, power characteristics, sprinting, jumping, and intermittent endurance performance in collegiate male players. Twenty-three players participated (19.7 ± 1.6 yrs; 71.8 ± 7.1 kg; 176.5 ± 5.1 cm). Measurements of interest in body composition included body fat percentage (BF%), lean body mass (LBM), and body mass (BM). Power characteristics were measured with an unloaded squat jump (SJ0) and loaded SJ at 20 kg (SJ20) and 40 kg (SJ40), and unloaded countermovement jump (CMJ0). Power assessments included peak power (PP) and PP allometrically scaled (PPa). Strength characteristics were assessed using isometric mid-thigh pull. Strength assessment included isometric peak force (IPF) and IPF allometrically scaled (IPFa). Performance measures included 10m and 20 m sprint time, CMJ0 jump-height, and Yo-Yo intermittent endurance test level 1 distance. Significant correlations ranging from moderate to very large were found for LBM and CMJ jump height (CM0 JH) (p = 0.01, r = 0.50); BF% and sprint times at 10 m (p = 0.03, r = 0.44) and 20 m (p = 0.02, r = 0.50). PP and PPa from SJ0 and CMJ0 were significantly correlated to 10m sprint time (p < 0.05, r = -0.45 to -0.53) and 20 m sprint time (p < 0.05, r = -0.40 to -0.49). Our findings agree with previous literature in that body composition and power characteristics are directly related to soccer-related performance.

Relationships Between Measures of Functional and Isometric Lower Body Strength, Aerobic Capacity, Anaerobic Power, Sprint and Countermovement Jump Performance in Professional Soccer Players

The purpose of this study was to assess a wide range of physiological and performance variables and investigate whether and to what extent these variables are associated with each other in soccer. Twenty-five male soccer players (25.1 ± 4.56 years; body mass, 75.2 ± 5.92 kg; body height, 180.6 ± 5.45 cm) performed: 5- and 30-m sprints (T5m and T30m, respectively), 1-repetition-maximum (1RM) half squat, maximal voluntary isometric contraction (MVIC) of the knee extensors, countermovement jump (CMJ) to obtain vertical jump height (CMJ_height) and power output (CMJ_power), the 10-s Wingate Anaerobic Test (WAnT) to obtain peak power (P_max), and the 20-m multi-stage shuttle run test (MST) to evaluate aerobic capacity. 1RM, MVIC, and P_max were normalized to body mass. Large negative correlations were found between sprint times and 1RM half back squat/BM (r = -0.510 to -0.570, r² = 0.260–0.325, both p < 0.01) and P_max/BM (r = -0.501, r² = 0.251, p < 0.01). T30m most strongly and negatively correlated with CMJ_height (r = -0.744, r² = 0.554, p < 0.001). WAnT-determined P_max showed a very large correlation between absolute P_max and knee-extensor MVIC (r = 0.827, r² = 0.684, p < 0.001) and large correlations between absolute P_max and 1RM half squat (r = 0.674, r² = 0.454, p < 0.001) and CMJ_power (r = 0.579, r² = 0.335, p < 0.01). We also identified a large inverse relationship between CMJ_height and T30m (r = -0.744, r² = 0.554, p < 0.001) and large positive correlation between CMJ_height and MVIC/BM (r = 0.702, p < 0.001). The results demonstrate that elite soccer players with greater lower body strength (quantified by the MVIC of the knee extensor and the 1RM half squat) show better sprint and CMJ performance, suggesting the incorporation of soccer-specific resistance training to develop lower body musculature and therefore maximize sprinting ability. The higher correlation coefficients found between T30m and the physiological and athletic measures compared with T5m promote the use of this sprint distance when assessing performance. The use of relative measures (normalized to body mass) is advisable when comparing strength variables with sprint and CMJ performance or anaerobic power. Considering the correlations of WAnT-determined P_max versus CMJ_power, coaches should administer tests that assess jumping and linear sprint performance rather than the cycling-specific WAnT.

Anthropometric and fitness associations in U17 Italian football players

BACKGROUND

The purpose of this study was to determine possible relationships between anthropometric characteristics and functional capacities in young football (soccer) players.

METHODS

Anthropometric characteristics, estimated peak height velocity (PHV), muscular endurance (sit-up), lower-limb power (countermovement jump, CMJ), sprint time over 5 and 15 m (T5 and T15), agility (Arrowhead agility test), repeated sprint ability (RSA), intermittent recovery capacity (Yo-Yo intermittent recovery test, Yo-Yo IR1) and technical skills (short dribbling tests) were assessed in a group of U17 players (N.=47) competing at regional level. Magnitude-based inferences were used for analyses.

RESULTS

Players with later PHV had greater muscle endurance (r [90% CIs] =0.41 [0.18; 0.59]) and CMJ (r=0.47 [0.25; 0.64]). Body mass, height and percentage of fat mass were positively associated to T5 and T15 (r=0.24-0.47). CMJ was moderately associated with agility, T5, T15 and Yo-Yo IR1 performance (r=-0.42 [-0.60; -0.19], -0.57 [-0.71; -0.38], 0.35[0.11; 0.54], respectively). Quickest players over 15 m were also the most agile and the most capable to perform intermittent recovery exercise (r=0.30-0.36). No significant correlations were found for RSA and other variables.

CONCLUSIONS

Body size is likely detrimental for power-related capacities (tallest and heaviest players reported the lowest sprint performance). Notwithstanding, sprint and jump were related to greater intermittent recovery performance. However, caution should be taken when generalizing our findings, given our reduced sample size. In addition, our observed correlations were of small-to-moderate magnitude, and therefore, future research should explore further determinants of functional capacities in these age-group players.

Speed of Thought and Speed of Feet: Examining Perceptual-Cognitive Expertise and Physical Performance in an English Football Academy

The world’s greatest professional football players are able to execute effective tactical decisions as well as fulfil various physical demands. However, the degree to which both are associated with greater potential in a football academy is unknown. Therefore, the aim of this study was to investigate decision-making skill and physical performance as contributing factors to coach potential rankings in an English football academy. Ninety-eight outfield academy players (Foundation Development Phase [FDP] under-9 to under-11 n = 40; Youth Development Phase [YDP] under-12 to under-16 n = 58) participated in the study. They engaged in 45 film-based simulations at two occlusion phases (e.g., the visual display is cut-off at a precise time during an action), firstly “during” and secondly “post” execution, to examine decision-making skill. Participants also completed four fitness tests to examine physical performance. A classification of “higher-potentials” (top third) and “lower-potentials” (bottom third) were applied through coach rankings. Independent t-tests compared the decision-making and physical performance tests. Higher-potentials made significantly more accurate decisions within the “post” phase within the FDP (P < 0.05) and the “during” phase within the YDP (P < 0.05). Additionally, higher-potentials were significantly faster for the 0–30 m sprint in both the FDP and YDP (P < 0.05), with higher-potentials within the YDP also significantly faster in the 0–10 m sprint (P < 0.05) and jumped significantly higher in the countermovement jump (P < 0.05). These findings indicated that greater football potential may be associated with superior perceptual-cognitive expertise and quicker sprint ability in both academy age phases, with a greater discriminatory function within the older cohort.

Variations of estimated maximal aerobic speed in children soccer players and its associations with the accumulated training load: Comparisons between non, low and high responders

The aim of this study was twofold: (i) to examine the variations of estimated maximal aerobic speed between non, low and high responders and (ii) to analyze the relationships between accumulated training load parameters and variations of maximal aerobic speed in children soccer players. Forty-four male soccer players were assessed three times during the early and mid-season (second to fifth month of the season) and were monitored daily over the period of analysis using the rating of perceived exertion (RPE), recording the training duration (in min) and calculating the session-RPE (sRPE). Pairwise comparisons revealed that maximal aerobic speed (MAS) was greater for the third assessment than the first (p-value [p] = 0.003; standardized effect of Cohen [d] = 0.355) and second (p = 0.013; d = 0.193) assessments. Large correlations were found between MAS and accumulated RPE, accumulated time, and accumulated sRPE. Moreover, non, low and high responders differed in ΔMAS (p<0.001) with the last group presenting the largest improvement in MAS. Results suggest that children with lower MAS baseline levels will improve more this capacity over the early and mid-season period compared to children with better baseline levels. Moreover, associations between accumulated training load and MAS were found, suggesting that the training effort can be related with aerobic capacity changes.

Influence of playing position and laterality in centripetal force and changes of direction in elite soccer players

The purpose of the present study was to: (a) assess centripetal force (CentF) and changes of direction (COD) in elite soccer players according to playing position (central defender, CD; lateral defender, LD; central midfielder, CM; lateral midfielder, LM; forward, FW), laterality (right-footed vs. left-footed) and field zone (central vs. lateral), and (b) analyze the relationship between anthropometric characteristics (age, weight, height, body mass and fat mass) and non-linear locomotion workload. Thirty professional soccer players (age: 26.57±5.56 years) were tracked during the 2017–2018 season during friendly, national and international matches (38 total games) using inertial measurement devices. CentF and COD were the variables extracted for analysis. A one-way ANOVA was used for playing position comparison, a t-test for laterality and field zone, and Pearson’s correlation coefficient to analyze relationships between anthropometric characteristics and dependent variables. There were differences by playing position in COD (556.33-to-412.18), R₂₀COD (484.36-to-354.81) and R₆₀COD (48.38-to-38.61) (p < .01; ω_p² = 0.03-to-0.05; CD>CM>LD>LM = FW); in COD_HIA (49.75-to-37.11), R₂₀COD_HIA (16.04-to-9.11) and R₆₀COD_HIA (10.64-to-9.11) (p < .01; ω_p² = 0.03-to-0.07; CM>FW>LM>CD = LD); in COD_SPRINT (14.56-to-8.40) and R₂₀COD_SPRINT (3.29-to-1.40) (p < .01; ω_p² = 0.03-to-0.04; FW = LM = CM>CD = LD); and in CentF_MAX both in clockwise (992.04-to-902.09N) and counterclockwise (999.24-to-872.61N) directions (p < .02; ω_p² = 0.02-to-0.07; FW = CD>CM = LM = LD). The highest values of counterclockwise CentF were performed by left-footed players in the central zone (p < .001; d = 0.71-to-1.44) and clockwise CentF by right-footed players (p < .001; d = 0.04-to-0.55) in the lateral field zone. Moderate correlations were found between age, body mass and high intensity/sprints COD and repeated COD ability (p < .05; r = 0.235-to-0.383). Therefore, team staff should consider anthropometric characteristics, playing position, laterality and field zone to individualize training workload related to non-linear locomotion in soccer.

Train Like You Compete? Physical and Physiological Responses on Semi-Professional Soccer Players

Background: Decision-making in soccer has repercussions and depends on the environment of training or competition. The demands on the players can reveal if the decision-making is similar or different from that required during competition. Objectives: The aim of this study was to assess the physical and physiological responses of players in training matches (TM) and official competition matches (CM) according to the playing position (external defenders, internal defenders, midfielders, and forwards/extremes). Methods: Twenty semi-professional male soccer players and 10 CM (n = 40) and 10 TM (n = 40) were studied using global positioning system technology, and paired and one-way ANOVA tests were carried out to compare physical (distances and number of sprints) and physiological (heart rates) responses with the factors a) match environments (TM and CM) and b) the playing position, respectively. Results: The results revealed that during CM, players covered higher total distance, partial distances, and sprints at different speeds (0–21 km/h) and produced higher physiological responses. Midfielders covered the greatest total distance in both TM (7227.6 m) and CM (11,225.9 m), in comparison to the other playing positions. However, forwards and extremes spent more time (56.8% of the CM [d = 0.78]) at 76% to 84% of their maximal heart rates. Conclusions: First, the physical and physiological responses in TM were significantly lower than in CM. Second, these responses were different according to the playing position, so this study was able to verify the exact amount of variation between the load produced in TM and CM. These results will help the coach and technical staff to design training tasks to complement the responses found in TM.

Somatotype and Body Composition in Young Soccer Players According to the Playing Position and Sport Success

Cárdenas-Fernández, V, Chinchilla-Minguet, JL, and Castillo-Rodríguez, A. Somatotype and body composition in young soccer players according to the playing position and sport success. J Strength Cond Res 33(7): 1904-1911, 2019-Soccer players undergo an evolution in their body composition throughout the growth and passage through the different base stages, that is, childhood, puberty, and adolescence. The aim of this study was to analyze the morphology and body composition of U14, U16, and U19 soccer players, taking into account in addition, their sport success endorsed through the regularity participation and their relation with the different playing positions occupied during competition (goalkeeper, external defender, central defender, midfielder, and forward/extreme). For that, a total of 174 male young soccer players were evaluated anthropometrically. Dominant somatotype of the players was, according to their playing position, meso-endomorphic in goalkeepers, central for external defenders, balanced ectomorph in central defenders, balanced mesomorph in the case of midfielders, and meso-ectomorph in forwards/extremes. Taking into account that sport performance is directly mediated by the body composition of athletes, the differences found suggest a marked specialization between the goalkeepers and forwards, establishing significant differences between them. Further studies would be needed to evaluate the influence of individual maturation development vs. sports training on the conformation of a certain anthropometric profile of a soccer player and its relation with the different playing positions occupied on the pitch during the game.

A Review of Countermovement and Squat Jump Testing Methods in the Context of Public Health Examination in Adolescence: Reliability and Feasibility of Current Testing Procedures

BACKGROUND

In the context of a public health physical fitness (PF) examination in adolescence, a countermovement jump (CMJ) and a squat jump (SJ) are two vertical jump (VJ) tests widely used to evaluate lower limb muscle strength and power, respectively. The main criticism of both the CMJ and SJ test is the lack of test standardization. Therefore, the objectives of this review are: (a) to gather information about both jumps; (b) to investigate whether it is possible to identify common procedures referred to in the CMJ and SJ technical execution, and (c) to design standard operating procedures (SOPs) to promote CMJ and SJ standardization in an adolescent population aged 12-18 years.

METHODS

The review partially adopted the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Statement (PRISMA). Due to growing attention in monitoring physical health through field tests in recent years, articles were collected using the PubMed, Web of Science, and Scopus databases from January 2009 to July 2019. Original articles in which CMJ or SJ were used to assess the muscular strength in adolescents were eligible for further analysis. Articles written in English was imposed as a limit.

RESULTS

A total of 117 studies met the inclusion criteria. The description of the CMJ and SJ test procedures was different within the literature, with discrepancies in the jump technique, number of jumps, and measurement devices used.

CONCLUSIONS

A lack of method standardization for both the CMJ and the SJ test was identified. Based on the literature, SOPs for both VJs were proposed. These are useful in the context of public health PF examination in adolescents, as they facilitate an unbiased comparison of jump performance data between published studies.

Muscle fitness and its association with body mass index in children and adolescents aged 7-18 years in China: a cross-sectional study

BACKGROUND

The present study was the first one aimed to investigate the current muscle fitness and its associated factors among children and adolescents in mainland China.

METHODS

From Nov 2013 to Jul 2014, 2283 children and adolescents aged 7-18 were recruited in Hainan and Shaanxi Provinces in China by cross-sectional design. Information on anthropometry and muscle fitness, measured by hand grip strength (GS), vertical jump (VJ) and sit-and-reach (SR), were collected. Analysis of covariance was performed by using general linear regression models to identify the association between BMI and muscle fitness.

RESULTS

The means of GS, VJ and SR in boys were 22.30 ± 11.55 kg, 22.93 ± 6.80 cm and 3.58 ± 7.31 cm, respectively, and in girls were 16.61 ± 6.87 kg, 18.11 ± 4.08 cm and 7.18 ± 5.72 cm, respectively. GS (from 8.26 kg in the 7-8-year-old group to 27.91 kg in the 17-18 group) and SR (from 1.75 cm in the-8-year-old group to 10.12 cm in the 17-18 group) increased with age (both p for trend < 0.001). Boys had higher GS and VJ, but significantly lower SR than girls in each age group (p < 0.001). After adjusting for age, sex, residential areas and study regions, GS increased with elevated BMI (compared with normal weight group, the regression coefficient for thinness and overweight/obesity were - 2.997(95%CI: -3.693 to - 2.301) and 1.220 (95%CI: 0.285 to 2.155), respectively. With the p values less than 0.001 and 0.011, respectively). For VJ, there was no difference found between normal weight group and overweight/obesity group (p = 0.550), but the thinness group had the lowest performance (regression coefficient = - 2.681, 95%CI from - 3.965 to - 1.397, p < 0.001). For SR, compared with normal weight group, the regression coefficients for thinness and overweight/obesity were - 1.313(95%CI: -2.228 to - 0.399) and - 1.623(95%CI: -3.216 to - 0.030) respectively, both p < 0.05.

CONCLUSIONS

Increased body weight may have a positive association with isometric muscle strength measured by grip strength, but a negative one with strength of lifting the body. Sex difference was also found in the performance of flexibility.

Changes Over a Decade in Anthropometry and Fitness of Elite Austrian Youth Soccer Players

Increases in physical (e.g., high-intensity running and sprinting), technical (e.g., passing rate), and tactical (e.g., player density) aspects made elite level soccer more challenging within the past years. The aim of the study was to evaluate whether these evolutions are also been reflected in changes in anthropometric and fitness characteristics between former (2002 to 2005) and current (2012 to 2015) elite Austrian youth development center (U13 to U14) and soccer academy (U15 to U18) players. A battery of anthropometric, general and soccer-specific fitness tests was conducted annually at the end of each year. Independent t-test and Cohen’s d (ES) were calculated to compare the two four-year periods (2530 vs. 2611 players) at each age group separately. Current players were significantly faster in 20 m sprint (ES = 0.26–0.50) and reaction test (ES = 0.15–0.39, except for U18), but less flexible at sit-and-reach (ES = –0.19 to –0.55), in all age categories. Whereas height (ES = 0.26–0.32), body mass (ES = 0.11–0.18) and countermovement jump (ES = 0.24–0.26) increased significantly at youth development center level, current academy players performed superior at shuttle sprint (ES = 0.21–0.59), hurdles agility run (ES = 0.24–0.49), and endurance run (ES = 0.11–0.20). These changes over time in speed, change-of-direction ability, lower-body power, coordination, and endurance were attributed to modern training approaches (e.g., modified games and change-of-direction drills) and modifications in selection politics (e.g., coaches favor speed and decision-making skills).

Maximum Oxygen Uptake of Male Soccer Players According to their Competitive Level, Playing Position and Age Group: Implication from a Network Meta-Analysis

The aim of the present meta-analysis was to compare the maximum oxygen uptake (VO2max) characteristics of male soccer players relative to their competitive level, playing position and age group and the interaction between them. The meta-analysis was based on 16 studies, employing 2385 soccer players aged 10-39 years. Higher-level soccer players showed greater (ES = 0.58 [95% CI 0.08-1.08], SE = 0.25, var = 0.06, z = 2.29, p = 0.022) VO2max performance with respect to their lower level counterparts. Furthermore, lower VO2max values in goalkeepers than defenders (ES = 1.31 (SE 0.46) [95% CI 0.41-2.21], var = 0.21, z = 2.84, p = 0.004) and midfielders (ES = 1.37 (SE 0.41) [95% CI 0.58 to 2.17], var = 0.16, z = 3.40, p = 0.001) were found. Thus, VO2max increased significantly with age (all, p < 0.01): Under 10 versus Under 11 years, Under 11 versus Under 12 years, Under 12 versus Under 13 years, Under 13 versus Under 14 years, Under 14 versus Under 15 years and Under 16-18 versus Under 20-23 years. VO2max performance is the most powerful discriminator between higher and lower-level soccer players. These findings indicate also the need for sports scientists and conditioning professionals to take the VO2max performance of soccer players into account when designing individualized position specific training programs.

Age-related differences in flexibility in soccer players 8-19 years old

BACKGROUND

Muscle flexibility is a main component of health-related fitness and one of the basic components of fitness for the performance in some sports. Sport and health professionals require the flexibility profile of soccer to define quantitative aims in the training of flexibility. The aim of this study was to identify age-related differences in lower extremity flexibility in youth soccer players.

METHODS

Seventy-two young male soccer players (age: 13.0 ± 3.1 y; body mass: 50.5 ± 15.3 kg; stature 158.2 ± 16.8 cm; BMI: 19.6 ± 2.6 kg/m2) completed this study. Measures of eleven passive hip (hip extension (HE), hip adduction with hip flexed 90°(HAD-HF90°), hip flexion with knee flexed (HF-KF) and extended (HF-KE), hip abduction with hip neutral (HAB) and hip flexed 90°(HAB-HF90°), hip external (HER) and internal (HIR) rotation), knee (knee flexion (KF)) and ankle dorsiflexion (ankle dorsiflexion with knee flexed (ADF-KF) and extended (ADF-KE)) ranges of motion (ROM) were taken. Descriptive statistics were calculated for hip, knee and ankle ROM measured separately by leg (dominant and non-dominant) and age-group (U10, U12, U14, U16 and U19). The data was analysed using a one-way analysis of variance (ANOVA) to examine the interaction of 11 ROM in the different players' age-group.

RESULTS

Generally, U10 and/or U12 soccer players obtain the highest mean value in almost all ROM evaluated (U10: HAD-HF [39.6° ± 4.3°], ADF-KE [32.3° ± 4.1°], HER [63.5° ± 5.6°] and HAB-HF90°[64.1° ± 7.5°]; U12: HE [17.7° ± 6.2°], HAB [35.6° ± 3.0], HIR [60.8° ± 4.7°] and KF [133.8° ± 7.1°]). Nonetheless, significant differences between the players' age-groups are just found in HAD-HF90°(p = .042; ES = .136), HAB (p = .001; ES = .252), HIR (p = .001; ES = .251), HER (p < .001; ES = .321) and HAB-HF90°(p < .001; ES = .376) ROM, showing a progressive and irregular decrease in these ROM until the U19 team.

CONCLUSION

The findings of this study reinforce the necessity of prescribing exercises aimed at improving HAD-HF90°  ROM in U16, HAB ROM in U14, HIR ROM in U16 and U19, HER ROM in U12 and U19, and HAB-HF90°  ROM in U16 and U19 players within everyday soccer training routines.

Functional performance, anthropometric parameters and contribution to team success among Italian "Serie A" elite goalkeepers during season 2016-2017

BACKGROUND

Soccer is the world's game, played by more than 120 million people. Different physical abilities, morphological and physiological characteristics are required for different playing positions. The purpose of this study is to describe anthropometric parameters and functional performances of goalkeepers, and these relationship with team success.

METHODS

The study population consisted of 92 professional goalkeepers from the Italian soccer "Serie A" league. Anthropometric measurements and indicators of performance of matches were obtained from the Italian soccer league. Goalkeepers were divided into first-choice and substitutes.

RESULTS

Goalkeepers who played at least one match were significantly older and heavier than those who did not play any game (P<0.0001). Minutes on the pitch, goals conceded, total saves and saves from both play sets and free kicks were significantly higher in the first-choice goalkeepers as compared to substitutes. However, by comparing first-choice with substitutes no significant differences for the ratio between goals against and saves by minutes played were observed. A significant positive correlation between points obtained by the team and ratio of goals conceded by minutes played (R=0.55; P<0.0001) as well as ranking position of the team achieved at the end of the season and the ratio of total saves by minutes played (R=0.51; P=0.001) was observed. A significant but inverse correlation between points obtained by the team and goal conceded was reported (R=-0.80; P<0.0001), as well as point obtained and ratio of total saves by minutes played (R=0.51; P=0.001). A lower ratio of goals conceded by minutes played was a significant predictor of total points achieved by the team (β=0.712, SE=0.15; P<0.0001). Finally, a higher ratio of goal conceded by minutes played was also associated with a higher probability of success for the team at the end of the season. Goalkeepers who completed the season with a ratio of goal against by minutes played greater than 57.5 minutes had an increased probability of leading their team to the first 6 positions of the final ranking (OR=24.7, 95% CI: 2.1-297.3; P=0.01).

CONCLUSIONS

Performance activities of the goalkeepers included in the rosters of the Italian soccer league significantly influenced the success of their team. A lower ratio of goals conceded by minutes played resulted to be the most significant predictor of overall team success. The present research extended previous research underlining the central role of goalkeeper for team success.

The effect of two different speed endurance training protocols on a multiple shuttle run performance in young elite male soccer players

There is not enough evidence on the impact of different speed endurance training regimes on footballers' ability to perform multiple shuttle run performance. This study examined the effect of 4 weeks of speed endurance maintenance (SEM) and speed endurance production (SEP) training on the 5-meter multiple shuttle run test (5-m MST) performance in young elite soccer players. A parallel two-groups, longitudinal design was used. Fifteen players were divided to either SEM (8 repetitions of 20-s all-out sprint interspersed with 40 s of recovery) or SEP (8 repetitions of 20-s all-out bout interspersed with 120 s of recovery) training group. SEM improved the ability to tolerate fatigue and maintained the performance development during the 5-m MST while SEP increased only the 1^st sprint showing, simultaneously, an increased fatigue index and performance decrement. The selection of which training regimes to prioritize should be based on the players' characteristics and individual game requirements Abbreviations: SEP: Speed Endurance Production; SEM: Speed Endurance Maintenance; PRE: Baseline; POST: End of experimental protocol; 5-m MST: 5-meters Multiple Shuttle Run Test; TD: Total Distance; FI: Fatigue Index; MSTdec: Percentage Decrement Score; BMI: Body Mass Index.

Talent identification for soccer: Physiological aspects

OBJECTIVES

Soccer coaches are always looking to discover the next star player, without investing the necessary resources, time, and effort into a player's development. In the modern era, talent identification in soccer seems to be a comparative process rather than a developmental process. This article will look at the physiological profiles of soccer players in the modern era and how testing and talent identification processes should coincide with this data.

DESIGN

An extensive literature search identifying the physiological attributes of soccer players that are required to compete at an elite level was conducted. An examination of the methods to test these attributes was also conducted.

METHODS

Studies were assigned into three areas to understand the physiological aspect of soccer: physiological testing methods, benchmark values, and correlations between different tests.

RESULTS

A testing battery was established to test the key physiological attributes of prospective youth soccer players. Benchmark levels were also identified to allow coaches to understand areas of improvement.

CONCLUSIONS

Using a physiological testing battery will allow teams to track their players' progress throughout their developmental years. This allows coaches to consistently identify a player's strengths and weaknesses, as well as allow players who may experience late maturation to still be identified.

Differences in Physical Performance According to the Competitive Level in Amateur Handball Players

Estibaliz, R, Fabio, N, Rodrigo, RC, Daniel, C, Josune, RN, and Javier Y. Differences in physical performance according to the competitive level in amateur handball players. J Strength Cond Res 34(7): 2048-2054, 2020-The aim of this study was to compare physical performance in amateur handball players of 2 different competitive levels. Thirty-four senior handball players were divided into 2 groups according to their competitive level (regional category: REG or national category: NAC). Although no significant differences were found between groups in any of the horizontal jump (HJ) or vertical jump (VJ) variables (p > 0.05), NAC players obtained a better performance in the repeated sprint ability (RSA) test (RSABest [the best attempt] and RSATT [the total time in the total of sprints] in 15 m and 30 m), in change of direction ability (CODA) and in the Yo-Yo Intermittent Recovery Test Level 1 (YYIR1) test (p < 0.01, effect size = -1.32 to 1.75, large). A significant association was observed between the body mass index (BMI) and the HJ or VJ capacity (r = -0.35 to -0.55, p < 0.01), the RSA15mBest and RSA30mBest (r = 0.41 to 0.59, p < 0.01), and YYIR1 distance (r = -0.54, p ≤ 0.05), and a also between the performance in the HJ or the VJ and the RSA15mBest and RSA30mBest, the CODA and the YYIR1, and between the RSA30mBest and the YYIR1 (r = -0.54, p ≤ 0.05). Specific strength and conditioning programs should aim toward improving RSA, CODA, and YYIR1, as these abilities may be needed at higher levels of competition. The programs also should aim toward improved HJ and VJ abilities, given their association with RSA, CODA, and YYIR1 performance. Moreover, maintaining an adequate BMI may aid players to sustain greater physical performance levels.

Anthropometric and physiological characteristics of male soccer players according to their competitive level, playing position and age group: a systematic review

INTRODUCTION

The aim of the present systematic review was to profile soccer players' anthropometric, physiological, and physical attributes relative to different competitive levels, playing positions and age groups.

EVIDENCE ACQUISITION

The systematic search was conducted using different databases and according to the Population/Intervention or Exposure/Comparison/Outcome(s) [PICO] criteria.

EVIDENCE SYNTHESIS

The present review shows that the somatotype characteristics, percentage (%) of body fat, maximal oxygen uptake (VO2max), repeated-sprint ability (RSA), running speed, strength, and muscular power of the lower limbs were the most powerful discriminators between male soccer players of different competitive levels, playing positions, and age groups. Specifically, higher VO2max, muscle strength, muscular power (vertical jump height), running speed (10-30 m) and agility, and lower % of body fat were identified in elite soccer players (higher-level) compared to all other competitive levels (i.e., lower-level: sub-elite, amateur, recreational). As for the competitive level differences, higher VO2max, mean anaerobic power, RSA and sprint performances (5 to 20 m), and lower % of body fat and lower limbs' explosive capabilities (countermovement jump [CMJ] and squat jump [SJ]) were found in outfielders (forwards, midfielders, and defenders) as compared to goalkeepers, from a very youth age (8 years old). Concerning age-related performance, it appears that physical performance increased significantly with age.

CONCLUSIONS

These data, together with the fact that each position, age category, and playing level has a different physiological background in male soccer players, demonstrate that training programs should be individualized to each position, playing level and age category, as is already done with goalkeepers.

The effects of game types on intensity of small-sided games among pre-adolescent youth football players

The aim of this study was to examine the effects of variations in pitch dimensions on pre-adolescent youth soccer players’ physiological responses during two different types of small-sided games (SSG). Sixteen young soccer players (age: 13.2 ± 0.6 years; body mass: 52.5 ± 7 kg; height: 163.4 ± 6 cm) participated in this study. They performed 4 vs. 4 stop-ball SSG (SB-SSG) vs. small-goals SSG (SG-SSG) with 4×4 min and 2 min of passive recovery in between, using 3 different pitch sizes (small: 10×15, medium: 15×20, and large: 20×25 m). Heart rate (HR), lactate concentration ([La-]), and rating of perceived exertion (RPE) were measured during each session. The results show that SB-SSG induced higher HR responses than SG-SSG for the 3 pitch sizes: for HR (167.2±3.0 vs. 164.5±3.0, 172.3±2.9 vs. 169.2±3.1, and 175.4±3.1 vs. 171.1±2.7 bpm; P<0.05, for small, medium, and large, respectively) and [La-] (7.1±1.0 vs. 6.5±1.04, 7.3±1.0 vs. 6.8±1.2, and 7.8±0.9 vs. 7.1±0.8 mmol·l^-1; P<0.05 on small, medium, and large pitches, respectively), whereas RPE scores were significantly higher during SB-SSG compared to SG-SSG (6.2±1.0 vs. 5.8±0.9; P<0.05, respectively) on the small pitch. In the present study higher physiological responses were observed in SSG in pre-adolescent young soccer players when using the stop-ball conditions in comparison with the small-goal rule for all pitch sizes – small, medium, and large. Stop-ball conditions in comparison with the small-goal rule for all pitch sizes – small, medium, and large.

Role of Vertical Jumps and Anthropometric Variables in Maximal Kicking Ball Velocities in Elite Soccer Players

Kicking is one of the most important skills in soccer and the ability to achieve ma ximal kicking velocity with both legs leads to an advantage for the soccer player. This study examined the relationship be tween kicking ball velocity with both legs using anthropometric measurements and vertical jumps (a squat jump (SJ); a countermovement jump without (CMJ) and with the arm swing (CMJA) and a reactive jump (RJ)). Anthropome tric measurements did not correlate with kicking ball velocity. Vertical jumps correlated significantly with kicking ball velocity using the dominant leg only (r = .47, r = .58, r = .44, r = .51, for SJ, CMJ, CMJA and RJ, respectively) . Maximal kicking velocity with the dominant leg was significantly higher than with the non-dominant leg (t = 18.0 4, p < 0.001). Our results suggest that vertical jumps may be an optimal test to assess neuromuscular skills involved in kicking at maximal speed. Lack of the relationship between vertical jumps and kicking velocity with the non-dominant leg may reflect a difficulty to exhibit the neuromuscular skills during dominant leg kicking.

Comparison of the Kinematic Patterns of Kick Between Brazilian and Japanese Young Soccer Players

Background

Kicking performance is the most studied technical action in soccer and lower limbs kinematics is closely related to success in kicking, mainly because they are essential in imparting high velocity to the ball. Previous studies demonstrated that soccer leagues in different countries exhibit different physical demands and technical requirements during the matches. However, evidencewhether nationality has any influence in the kinematics of soccer-related skills has not yet been reported. The nationality of the players is an aspect that might be also relevant to the performance in kicking.

Objectives

The aim of this study was to compare the lower limbs kinematic patterns during kicking, between Brazilian and Japanese young top soccer players.

Patients and Methods

Seven Brazilian (GA) and seven Japanese (GB) U-17 players performed 15 side-foot kicks each, with a distance of 20 m away from the goal, aiming a target of 1 × 1 m in upper corner, constrained by a defensive wall (1.8 × 2 m). Four digital video cameras (120 Hz) recorded the performance for further 3D reconstruction of thigh, shank and foot segments of both kicking and support limbs. The selected kicking cycle was characterized by the toe-off of the kicking limb to the end of the kicking foot when it came in contact with the ball. Stereographical projection of each segment was applied to obtain the representative curves of kicking as function of time for each participant in each trial. Cluster analysis was performed to identify the mean GA and GB curves for each segment. Silhouette coefficient (SC) was calculated, in order to determine the degree of separation between the two groups’ curves.

Results

Comparison between the median confidence intervals of the SC showed no differences between groups as regards lower limb patterns of movements. Task accuracy was determined by the relative frequency that the ball reached the target for all attempts and no differences were found (GA: 10.48 ± 14.33%; GB: 9.52 ± 6.51%; P = 0.88).

Conclusions

We conclude that lower limb kinematic patterns, in support and ball contact phases, are similar in young Brazilian and Japanese soccer players during free kicks when adopting the side-foot kick style.

Anthropometrics, Physical Performance, and Injury Characteristics of Youth American Football

BACKGROUND

Prior research has described the anthropometric and physical performance characteristics of professional, collegiate, and high school American football players. Yet, little research has described these factors in American youth football and their potential relationship with injury.

PURPOSE

To characterize anthropometric and physical performance measures, describe the epidemiology of injury, and examine the association of physical performance measures with injury among children participating within age-based divisions of a large metropolitan American youth football league.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

Demographic, anthropometric, and physical performance characteristics and injuries of 819 male children were collected over a 2-year period (2011-2012). Injury data were collected by the league athletic trainer (AT) and coaches. Descriptive analysis of demographic, anthropometric, and physical performance measures (40-yard sprint, pro-agility, push-ups, and vertical jump) were conducted. Incidence rates were computed for all reported injuries; rates were calculated as the number of injuries per 1000 athlete-exposures (AEs). Multinomial logistic regression was used to identify whether the categories of no injury, no-time-loss (NTL) injury, and time-loss (TL) injury were associated with physical performance measures.

RESULTS

Of the 819 original participants, 760 (92.8%) completed preseason anthropometric measures (mean ± SD: age, 11.8 ± 1.2 years; height, 157.4 ± 10.7 cm; weight, 48.7 ± 13.3 kg; experience, 2.0 ± 1.8 years); 640 (78.1%) players completed physical performance measures. The mean (±SD) 40-yard sprint and pro-agility measures of the players were 6.5 ± 0.6 and 5.7 ± 0.5 seconds, respectively; the number of push-ups and maximal vertical jump height were 16.5 ± 9.3 repetitions and 42.3 ± 8.4 cm, respectively. Players assigned to different teams within age divisions demonstrated no differences in anthropometric measures; 40-yard dash and pro-agility times differed significantly (P < .05) between players assigned to different teams. A total of 261 NTL and TL injuries were reported during 35,957 AEs (games: 22%, n = 7982 AEs; practices: 78%, n = 27,975 AEs). The overall incidence rate was 7.26 per 1000 AEs (95% CI, 6.37-8.14). Physical performance measures did not predict NTL or TL injuries (P > .05).

CONCLUSION

No practically meaningful differences existed in anthropometric or physical performance measures between teams within age-based levels of play. Findings suggest that age-only criterion for player groupings can evenly match in terms of physical performance.

Muscle Strength and Speed Performance in Youth Soccer Players

This study aimed to examine the relationship between maximum leg extension strength and sprinting performance in youth elite male soccer players. Sixty-three youth players (12.5 ± 1.3 years) performed 5 m, flying 15 m and 20 m sprint tests and a zigzag agility test on a grass field using timing gates. Two days later, subjects performed a one-repetition maximum leg extension test (79.3 ± 26.9 kg). Weak to strong correlations were found between leg extension strength and the time to perform 5 m (r = -0.39, p = 0.001), flying 15 m (r = -0.72, p < 0.001) and 20 m (r = -0.67, p < 0.001) sprints; between body mass and 5 m (r = -0.43, p < 0.001), flying 15 m (r = -0.75, p < 0.001), 20 m (r = -0.65, p < 0.001) sprints and agility (r =-0.29, p < 0.001); and between height and 5 m (r = -0.33, p < 0.01) and flying 15 m (r = -0.74, p < 0.001) sprints. Our results show that leg muscle strength and anthropometric variables strongly correlate with sprinting ability. This suggests that anthropometric characteristics should be considered to compare among youth players, and that youth players should undergo strength training to improve running speed.

Anthropometric and Somatotype Characteristics of Young Soccer Players: Differences Among Categories, Subcategories, and Playing Position

Considering that anthropometric parameters are important factors in the performance of the soccer players, the aim of this study was to explore the differences in anthropometric and somatotype characteristics of Italian young soccer players. Weight, height, body mass index, and somatotype of 112 young soccer players, grouped in Giovanissimi "A" (14 years), "B" (13 years), and "C" (12 years) as well as Allievi "B" (15 years) and "A" (16 years) and "Juniores" (older than 17 years), were evaluated. Statistical analysis tests were computed at p ≤ 0.05, and an analysis of variance for each somatotype was calculated to analyze the main effects and interactions of the factors: categories, subcategories, and playing position. Bonferroni's post hoc analysis was used to identify differences among mean values. Considering all subjects, we have found significant differences in categories, subcategories, and playing position between anthropometric values and a somatotype value of 2.8-3.8-2.9. Significant differences have found among goalkeepers and the others playing position in endomorphy (p ≤ 0.001) and with defenders and midfielders in ectomorphy (p < 0.01) components, whereas no differences in mesomorphy. Analyzing the interaction between subcategories and playing position factors, a significant effect was found only in the endomorphy component (p = 0.05). The analysis of anthropometric characteristic of Italian young soccer players indicates that players have high muscularity value and low adiposity. This study showed the presence of somatotype differences for playing position within categories also in the youngest categories and subcategories, in particular, in the endomorphy component. Young soccer players should be trained with more appropriate and specific training load to avoid the increased injury risk during adolescence.

Anthropometric factors related to sprint and agility performance in young male soccer players

Objective

To investigate the relationship between anthropometrics and sprint and agility performance and describe the development of sprint (acceleration) and agility performance in 10- to 16-year-old male soccer players.

Methods

One hundred and thirty-two participants were divided into three age groups, 10–12 years (mean 10.8±0.50), 13–14 years (mean 13.9±0.50), and 15–16 years (mean 15.5±0.24), with assessment of 20 m sprint with 10 m split time and agility performance related to body height and body mass within groups.

Results

In the 10- to 12-year-olds, there were no significant correlations between height, weight, and the performance variables, except for body mass, which was correlated to 10–20 m sprint (r=0.30). In the 13- to 14-year-olds, body height was significantly correlated with 10 m sprint (r=0.50) and 20 m sprint (r=0.52), as well as 10–20 m sprint (r=0.50) and agility performance (r=0.28). In the 15- to 16-year-old group, body height was correlated to 20 m (r=0.38) and 10–20 m (r=0.45) sprint. Body mass was significantly correlated to 10 m spring (r=0.35) in the 13- to 14-year-olds, as well as 20 m (r=0.33) and 10–20 m (r=0.35) sprint in the 15- to 16-year-olds.

Conclusion

Height and body mass were significantly correlated with sprint performance in 13- to 16-year-old male soccer players. However, the 10- to 12-year-olds showed no significant relationship between sprint performance and anthropometrics, except for a small correlation in 10–20 m sprint. This may be attributed to maturation, with large differences in body height and body mass due to different patterns in the growth spurt. The agility performance related to anthropometrics was insignificant apart from a moderate correlation in the 13- to 14-year-olds.

Anthropometric and physiological characteristics of Melanesian futsal players: a first approach to talent identification in Oceania

This study assessed the anthropometric and physiological characteristics of elite Melanesian futsal players in order to determine the best performance predictors. Physiological parameters of performance were measured in 14 Melanesian (MEL-G, 24.4±4.4 yrs) and 8 Caucasian (NMEL-G, 22.9±4.9) elite futsal players, using tests of jump-and-reach (CMJ), agility (T-Test), repeated sprint ability (RSA), RSA with change-of-direction (RSA-COD), sprints with 5 m, 10 m, 15 m, and 30 m lap times, and aerobic fitness with the 30-15 intermittent fitness test (30-15 IFT). The anthropometric data revealed significantly lower height for MEL-G compared with NMEL-G: 1.73±0.05 and 1.80±0.08 m, respectively; P = 0.05. The CMJ was significantly higher for MEL-G than NMEL-G: 50.4±5.9 and 45.2±4.3 cm, respectively; P = 0.05. T-Test times were significantly lower for MEL-G than NMEL-G: 10.47±0.58 and 11.01±0.64 seconds, respectively; P = 0.05. MEL-G height was significantly related to CMJ (r = 0.706, P = 0.01), CMJ_peakP (r = 0.709, P = 0.01) and T-Test (r = 0.589, P = 0.02). No significant between-group differences were observed for sprint tests or 30-15 IFT, including heart rate and estimated VO_2max. Between groups, the percentage decrement (%Dec) in RSA-COD was significantly lower in MEL-G than NMEL-G (P = 0.05), although no significant difference was noted between RSA and RSA-COD. Within groups, no significant difference was observed between %Dec in RSA or RSA-COD; P = 0.697. This study presents specific anthropometric (significantly lower height) and physiological (significantly greater agility) reference values in Melanesians, which, taken together, might help coaches and physical fitness trainers to optimize elite futsal training and talent identification in Oceania.