Physiological profile of Asian elite youth soccer players

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.

Quantification of training and match load in elite youth soccer players: a full-season study

BACKGROUND

The present study aimed to quantify training and match load in elite young soccer players over the course of an entire season.

METHODS

Using a longitudinal design, session-rate of perceived exertion (s-RPE) and its metrics [weekly acute workload (wAW), acute to chronic workload ratio (wACWR), training monotony and training strain] were examined in twenty-one elite young soccer players (mean±standard deviation; age, 16.1±0.2 years; height, 176.8±5.6 cm; body mass, 67.3±5.7 kg; BMI, 21.5±1.4 kg/m2; VO2max, 47.6±3.8 ml.kg-1.min-1) during the whole season containing 4 meso-cycles: Pre-season (Pre-S), Earlyseason (Ear-S), Mid-season (Mid-S), and End-season (End-S).

RESULTS

Repeated-measures analysis of variance examined variations in s-RPE load data across the 4 meso-cycles and 1-week of micro-cycle. Analyzing data revealed the End-S had a significant greater wAW compared to Early-S (p = 0.002, g = 0.96) and Mid-S (p < 0.001, g = 1.09). However, no differences between in-season periods were observed in wACWR (p = 0.524). The within-week variations revealed significant lower wAW in pre-match a day (MD-1) (p < 0.001), 1 day after match (MD+1) (p < 0.001) and 2 days after match (MD+2) (p < 0.001) compared to match day (MD) for overall team analysis. Additionally, analyses by playing position showed that fullbacks have a significant lower AW in MD+2 compared to MD (p < 0.029).

CONCLUSIONS

The periodization of training load indicated variations across the whole season in young elite players. The weekly micro-cycle perceived load could be identified as follows; there are higher training loads on MD-3 and MD-2 which was similar to intensities experienced by players throughout the match play and, furthermore, lower overall WL on the MD+1 and MD+2 in order to ensure the optimal recovery of the players.

Differences in gait and muscle strength of patients with acute and chronic anterior cruciate ligament injury

BACKGROUND

Anterior cruciate ligament (ACL) injury is one of the most common injuries of the area surrounding the knee. Muscle strength deficiency is observed following an ACL injury. Determining differences in muscle strength and gait between patients with acute and chronic ACL injury will provide crucial information for assessments and treatment plans.

METHODS

We evaluated 60 patients with ACL rupture. Patients were classified into acute and chronic groups. We compared measurements of anthropometric parameters, muscle strength, gait and functional questionnaire.

FINDINGS

The muscle strength of both knee extensors and flexors was higher in the chronic group than in the acute group. The muscle strength index for extensors was 57% in the acute group and 73% in the chronic group. However, the hamstring-to-quadriceps ratio for peak torque of the injured leg in the acute and chronic groups was similarly high at 98% and 101%, respectively. In gait, asymmetry in the hip and knee was observed in the acute group but not in the chronic group. The Knee Injury and Osteoarthritis Outcome Scores (KOOS) for symptoms, pain, activities of daily living, sports and recreational activities were higher in the chronic group than in the acute group.

INTERPRETATION

Compared with the acute group, the gait of the chronic group is more symmetrical, and the score of KOOS is also higher. The muscle training protocols could be strategically planned according to these differences. Patients with ACL injury are characterized high hamstrings-to quadriceps peak torque ratio.

[Effect of contextual factors in body composition of professional soccer players. A retrospective study]

Introduction

The requirements of physical demands in soccer have evolved in recent years, determining the need to investigate those aspects that condition athletic performance. The objective of this study was to describe the incidence of individualized training, company at meals, race, and demarcation on the anthropometric variables of professional soccer players since these four factors affect body composition, which is considered a predictor of performance and an indicator of lifestyle in these individuals. For this purpose, a retrospective study was developed in 51 professional players of the Spanish Football League Second Division B during the 2015/2016, 2016/2017, and 2017/2018 seasons. The anthropometric assessment was carried out under the technical standards of measurement recommended by the International Working Group of Kinanthropometry, adopted by the International Society for the Advancement of Kinanthropometry (ISAK). The results revealed that individualized training and company during meals were the factors that most influence exerted on the anthropometric variables that were collected. The values of fat mass and muscle mass, and the sum of fold measurements are sensitive to the effect of the intervention with these factors. The highest levels of interaction occurred between company during the meals and individualized training, and between demarcation and company during the meals. Considering body composition as an aspect to be taken into account in the development of performance, it should be considered that the application of certain training contents according to the individual characteristics and lifestyle of players are factors that may have a significant influence on professional soccer players.

The ball kicking speed: A new, efficient performance indicator in youth soccer

Success in different soccer skills like kicking depends on motor abilities achieved. Kicking is a soccer fundamental, which depends on many different and complex factors (technique, foot-ball interaction, ball flight, etc.). Therefore, it is important to identify players that are able to perform faster kicks using both dominant and non-dominant leg. The current study investigated some basic variables of different soccer kicking speed and their relevance to success in youth soccer academy. 119 players from the first and the second division participated to this study. They were randomly divided into age groups (U-15, U-17, and U19) and team status (first team, reserves). The diagnostic ability of the different ball kicking speed tests in capturing differences between first team players and reserves among different age categories were computed using the receiver operating characteristics analysis. Results demonstrated that first team players achieved better results when comparing to reserves in each category. In addition, differences were greater in the U-15 and the U-17 than in the U-19 age group. In conclusion, ball kicking speed could be one of the possible identification tools to evaluate players' success in youth soccer.

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.

Effect of strength and high-intensity training on jumping, sprinting, and intermittent endurance performance in prepubertal soccer players

The purpose of this study was to examine the effects of a 26-week on-field combined strength and high-intensity training on the physical performance capacity among prepubertal soccer players who were undertaking a competitive phase of training. Twenty-four prepubertal soccer players between the age of 8 and 9 years were randomly assigned to 2 groups: a control (C; n = 13) and an experimental group (S; n = 11). Both groups performed an identical soccer-training program, whereas the S group also performed combined strength and high-intensity training before the soccer-specific training. The 15-m sprint time (seconds), countermovement jump (CMJ) displacement, Yo-Yo intermittent endurance test (Yo-Yo IE), and Sit and Reach flexibility were each measured before (baseline) and after 9 (T2), 18 (T3), and 26 weeks (posttest) of training. There were no significant differences between the groups in any of the variables tested at baseline. After 26 weeks, significant improvements were found in the CMJ (6.72%; effect size [ES] = 0.37), Yo-Yo IE (49.57%, ES = 1.39), and Flexibility (7.26%; ES = 0.37) variables for the S group. Conversely, significant decreases were noted for the CMJ (-10.82%; ES = 0.61) and flexibility (-13.09%; ES = 0.94) variables in the C group. A significant negative correlation was found between 15-m sprint time and CMJ (r = -0.77) and Yo-Yo IE (r = -0.77) in the S group. Specific combined strength and high-intensity training in prepubertal soccer players for 26 weeks produced a positive effect on performance qualities highly specific to soccer. Therefore, we propose modifications to current training methodology for prepubertal soccer players to include strength and high-intensity training for athlete preparation in this sport.

Profile, correlation and structure of speed in youth elite soccer players

Speed, power and agility are important components of fitness and determine the level of success and performance in soccer. The aim of this study was to identify speed variables and to determine their mutual correlation and structure in youth elite soccer players. The research group consisted of players from the Czech U16 national team (n = 22, age = 15.6 ± 0.4 years). Speed variables were assessed using the following tests: a) linear speed: 5 m sprint (S5), 10 m sprint (S10) and 20 m flying sprint (F20); b) the agility: agility test 505 with turning on the dominant (A505D) and non-dominant legs (A505N) and the K-test (K) and c) ball velocity after an instep kick with the dominant (IKD) and non-dominant (IKN) legs. Significant dependence was found for S5 compared with S10, F20 vs. A505N, K vs. A505N (p < 0.01) and S10 vs. F20 (p < 0.05). The factor analysis revealed three components of the latent variable - speed. The first component consisted of linear sprint (S10, S20) and also partially consisted of maximum speed (F20). The second component was primarily composed of agility (A505D, A505N, K) and also included maximum speed (F20). The third independent component represented ball velocity after an instep kick (IKD, IKN). The speed variables in youth elite players exhibited significant heterogeneity from the perspective of performance, as determined by the monitored tests. The structure of the speed predisposition indicated that there were three components of speed. The results of our studies support the notion that each component of speed must be considered independently when designing training programmes.

Physiological response, time-motion characteristics, and reproducibility of various speed-endurance drills in elite youth soccer players: small-sided games versus generic running

PURPOSE

To quantify the physiological responses, time-motion characteristics, and reproducibility of various speed-endurance-production (SEP) and speed-endurance-maintenance (SEM) drills.

METHODS

Sixteen elite male youth soccer players completed 4 drills: SEP 1 v 1 small-sided game (SSG), SEP running drill, SEM 2 v 2 SSG, and SEM running drill. Heart-rate response, blood lactate concentration, subjective rating of perceived exertion (RPE), and time-motion characteristics were recorded for each drill.

RESULTS

The SEP and SEM running drills elicited greater (P < .05) heart-rate responses, blood lactate concentrations, and RPE than the respective SSGs (ES 1.1-1.4 and 1.0-3.2). Players covered less (P < .01) total distance and high-intensity distance in the SEP and SEM SSGs than in the respective running drills (ES 6.0-22.1 and 3.0-18.4). Greater distances (P < .01) were covered in high to maximum acceleration/deceleration bands during the SEP and SEM SSGs than the respective running drills (ES 2.6-4.6 and 2.3-4.8). The SEP SSG and generic running protocols produced greater (P < .05) blood lactate concentrations than the respective SEM protocols (ES 1.2-1.7). Small to moderate test-retest variability was observed for heart-rate response (CV 0.9-1.9%), RPE (CV 2.9-5.7%), and blood lactate concentration (CV 9.9-14.4%); moderate to large test-retest variability was observed for high-intensity-running parameters (CV > 11.3%) and the majority of accelerations/deceleration distances (CV > 9.8%) for each drill.

CONCLUSIONS

The data demonstrate the potential to tax the anaerobic energy system to different extents using speed-endurance SSGs and that SSGs elicit greater acceleration/ deceleration load than generic running drills.

H:q ratios and bilateral leg strength in college field and court sports players

One of the key components in sports injury prevention is the identification of imbalances in leg muscle strength. However, different leg muscle characteristics may occur in large playing area (field) sports and small playing area (court) sports, which should be considered in regular injury prevention assessment. This study examined the isokinetic hamstrings-to-quadriceps (H:Q) ratio and bilateral leg strength balance in 40 male college (age: 23.4 ± 2.5 yrs) team sport players (field sport = 23, soccer players; court sport = 17, volleyball and basketball players). Five repetitions of maximal knee concentric flexion and concentric extension were performed on an isokinetic dynamometer at two speeds (slow: 60°·s(-1) and fast: 300°·s(-1)) with 3 minutes rest between tests. Both legs were measured in counterbalanced order with the dominant leg being determined as the leg used to kick a ball. The highest concentric peak torque values (Nm) of the hamstrings and quadriceps of each leg were analyzed after body mass normalization (Nm·kg(-1)). Court sport players showed significantly weaker dominant leg hamstrings muscles at both contraction speeds (P < 0.05). The H:Q ratio was significantly larger in field players in their dominant leg at 60°·s(-1) (P < 0.001), and their non-dominant leg at 300°·s(-1) (P < 0.001) respectively. Sport-specific leg muscle strength was evident in college players from field and court sports. These results suggest the need for different muscle strength training and rehabilitation protocols for college players according to the musculature requirements in their respective sports.

Angiotensin-converting enzyme/vitamin D receptor gene polymorphisms and bioelectrical impedance analysis in predicting athletic performances of Italian young soccer players

We evaluated the association between 2 genetic polymorphisms known to be involved in fitness and performance, and anthropometric features, body composition, and athletic performances in young male soccer players with the goal of identifying genetic profiles that can be used to achieve maximal results from training. One hundred twenty-five medium-high-level male soccer players were genotyped for angiotensin-converting enzyme (ACE) I/D, and vitamin D receptor (VDR) FokI gene polymorphisms and scored for anthropometric measurements, body composition, and athletic performance. Body mass index, fat mass, fat-free mass, resistance, reactance, impedance, phase angle (PA), and body cell mass were measured. Athletic performance was evaluated by squat jump, countermovement jump (CMJ), 2-kg medicine ball throw, 10- and 20-m sprint time. We observed that the homozygous ff genotype of the VDR gene was significantly more represented in young soccer players than in a matched sedentary population. Values of reactance and PA were differently distributed in ACE and VDR genotypes with high mean values in subjects with DD (ACE) and FF (VDR) genotypes. No correlation was observed between ACE or VDR genotypes and 2-kg medicine ball throw, 10- and 20-m sprint times. The ID genotype of ACE was associated with the best performances in squat jump and CMJ. Our results suggest that determination of ACE and VDR genotypes might help select those young athletes harboring the most favorable genetic potential to succeed in soccer.

Comparação da performance funcional do membro inferior entre jovens futebolistas e jovens não treinados

INTRODUÇÃO: Em atletas, a utilização de testes de performance funcional permite avaliar com maior validade ecológica possíveis alterações do membro inferior observadas na prática desportiva. OBJETIVO: O objetivo do presente estudo consistiu na comparação da performance funcional do membro inferior entre jovens futebolistas e jovens não treinados. METODOLOGIA: A amostra foi constituída por 39 jovens do sexo masculino, divididos em dois grupos: um grupo composto por 19 futebolistas (idade = 16,8 ± 0,83 anos; peso = 69,8 ± 6,2 kg; altura = 176,6 ± 0,5 cm) e outro composto por 20 sujeitos não treinados (idade = 16,6 ± 0,8 anos; peso = 66,3 ± 11,0 kg; altura = 172,0 ± 0,8 cm). Para avaliação da performance funcional do membro inferior foram utilizados três testes: o Single-Leg Hop Test, o Quadrant Jump Test e o Hexagon Test. RESULTADOS: Os jovens futebolistas obtiveram melhor performance do que os jovens não treinados em ambos os membros inferiores no Single-Leg Hop Test (membro inferior direito: 124 ± 62 cm, membro inferior esquerdo: 127 ± 68 cm versus membro inferior direito: 99 ± 10 cm, membro inferior esquerdo: 97 ± 12 cm; p < 0.001), em ambas as direções, na execução do Hexagon Test (sentido dos ponteiros do relógio: 5,1 ± 0,6 s, sentido inverso: 4,9 ± 0,5 s versus sentido dos ponteiros do relógio: 6,0 ± 0,4 s, sentido inverso: 5,7 ± 0,4 s; p < 0.001) e no Quadrant Jump Test (32,4 ± 2,5 pontos versus 28,2 ± 2,5 pontos, p < 0.001). Dentro de cada grupo não foi encontrada diferença entre os dois membros inferiores no Single-Leg Hop Test, nem entre as duas direções do Hexagon Test. CONCLUSÕES: Os resultados do presente estudo indicam que jovens futebolistas apresentam melhor performance funcional do membro inferior do que jovens não treinados.