Correlations of Aerobic Capacity with External and Internal Load of Young Football Players during Small-Sided Games.

Aerobic capacity plays a crucial role in football performance, making it a focal point in training processes. Small-sided games (SSGs) are widely used in football training, but the relationship between aerobic capacity and running performance during SSGs remains unclear. The aim of this study was to investigate possible correlations between maximum oxygen uptake (VO2max) and running performance in youth football players in SSGs (4:4, 3:3, 2:2, 1:1) with three different pitch sizes per player (150, 100, 75 m2/player). Sixteen male U15 football players participated in the study. Players underwent the Yo-Yo intermittent recovery test level 1, and their VO2max was estimated based on their performance. Subsequently, players participated in SSGs wearing GPS devices to measure internal and external load. Pearson or Spearman correlation was applied for statistical analysis depending on the normal distribution of the data. The results reveal that, for 4:4 and 3:3 relationships, larger pitches led to a greater impact of aerobic capacity (total distance (TD): 4:4, 150 m2/pl, r = 0.715, p = 0.002; 100 m2/pl, r = 0.656, p = 0.006; 75 m2/pl, r = 0.586, p = 0.017). In the 2:2 relationship, the opposite was observed, with more correlations appearing on smaller pitches (TD: 2:2, 100 m2/pl, r = 0.581, p = 0.018; 75 m2/pl, r = 0.747, p < 0.001). In the 1:1 relationship, correlations with VO2max, total distance, and speed were observed only on the larger pitch. In conclusion, the aerobic capacity of young football players can influence running performance indicators in SSGs. Therefore, aerobic capacity could serve as a criterion for team composition, making SSGs more competitive. Additionally, the variation in correlations in the 2:2 relationship and their limited presence in the 1:1 relationship may be attributed to technical-tactical factors, such as increased ball contacts and one-on-one situations typically occurring in smaller setups.

Weekly External Load Correlation in Season Microcycles with Game Running Performance and Training Quantification in Elite Young Soccer Players.

The purpose of this study was to (a) correlate the weekly external training load with the game running performance in season microcycles and (b) specify the optimal training/game ratio of the weekly external load in elite youth soccer players. The total distance (TD), the high-speed running distance (HSRD) (19.8-25.2 km/h), the ZONE6 distance (>25.2 km/h), the acceleration (ACC) (≥+2 m/s2), and the deceleration (DEC) (≥-2 m/s2) were monitored with global positioning system (GPS) technology throughout 18 microcycles and official games. TD had a very high positive correlation average (r = 0.820, p = 0.001), the HSRD had a high positive correlation average (r = 0.658, p = 0.001), the ZONE6 distance and DEC had a moderate positive correlation average ((r = 0.473, p = 0.001) and (r = 0.478, p = 0.001), respectively), and the ACC had a low positive correlation average (r = 0.364, p = 0.001) between microcycles and games. Regarding the training/game ratio, the HSRD showed statistically significant differences between ratios 1.43 and 2.60 (p = 0.012, p ≤ 0.05), the ACC between ratios 2.42 and 4.45 (p = 0.050, p ≤ 0.05) and ratios 3.29 and 4.45 (p = 0.046, p ≤ 0.05), and the DEC between ratios 2.28 and 3.94 (p = 0.034, p ≤ 0.05). Considering the correlation between weekly training and game external load, high weekly training TD values correspond to higher game values, whereas HSRD, ZONE6 distance, ACC, and DEC, which determine training intensity, should be trained in a specific volume. Training/game ratios of 1.43, 2.42 to 3.29, and 2.28 to 3.11 seem to be optimal for HSRD, ACC, and DEC weekly training, respectively.

Relation of Jump and Change of Direction Inter-Limb Asymmetries with Fitness in Youth Male Soccer Players.

Background and Objectives: Asymmetries between the lower limbs were evaluated by both researchers and practitioners as they seem to be related to the occurrence of injuries and the effect on performance. The purposes of this study were to (a) detect asymmetries of the lower limbs using a unilateral jump (single-leg countermovement jump (SLCMJ)) and 505 agility test, and (b) examine asymmetry effects on fitness (acceleration, speed, squat jump, Illinois agility test), in U16 youth male soccer players. Materials and Methods: Twenty U16 soccer players performed an SLCMJ and a 505 test to calculate the asymmetry index. They also performed the above fitness tests. The difference between the lower limbs was tested using the paired samples t-test (dominant vs. non-dominant). The correlations between the asymmetries of the lower extremities with the performance indicators were tested using the Pearson's correlation test. The level of significance was set at p < 0.05. Results: The lower limbs differed significantly in the SLCMJ and 505 tests (p < 0.05). The only correlation was between the asymmetry in SLCMJ and performance in SJ (r = -0.641, p = 0.002). Asymmetries did not affect performance on most fitness tests. Conclusions: The two asymmetry tests identified asymmetries in different limbs. This indicates the variability in asymmetries and the need for specialized tests depending on the kinematic chain. The asymmetries observed should be eliminated using individualized training programs so that athletes are protected from injuries and from the possible negative impact on performance. Also, the detection of asymmetries in developmental age offers a greater time period for their elimination before the athlete enters professional sports.

Correlation of Fiber-Type Composition and Sprint Performance in Youth Soccer Players.

Metaxas, T, Mandroukas, A, Michailidis, Y, Koutlianos, N, Christoulas, K, and Ekblom, B. Correlation of fiber-type composition and sprint performance in youth soccer players. J Strength Cond Res 33(10): 2629-2634, 2019-The aim of this study was to examine the correlation between muscle fiber type and sprint performance in elite young soccer players of different age groups of the same team. Twenty-eight young players participated in this study (group U15, n = 8; group U13, n = 9; and group U11, n = 11). Anthropometric assessments, acceleration (10 m), and Bangsbo modified sprint test (30 m) were performed. Muscle biopsies were obtained from the vastus lateralis, and after that, fiber-type composition was determined by immunohistochemistry. No significant correlations were found between the sprint test and muscle fiber distribution for the groups U13 and U11 (p > 0.05). Also, no correlations were found between cross-sectional areas in the types of fibers with the sprint test in all groups (p > 0.05). A positive correlation was found between type I fibers and the performance in the acceleration test (10 m) (r = 0.77, p < 0.05) was found only in group U15 and a negative correlation between type IIA fibers and the performance in the acceleration test (10 m) (r = -0.89, p < 0.05). The correlations were observed only in group U15, which may indicate that the duration and the intensity of the soccer systematic training can affect the plasticity of the muscle fibers. Specific soccer training in youth is one of the factors that can affect fiber-type plasticity. The specific training programs and status of U15 are more intensive, and the exercises are oriented more to improve physical fitness.

Factors Affecting the Running Performance of Soccer Teams in the Turkish Super League.

Performance analysis in sports is a rapidly evolving field, where academics and applied performance analysts work together to improve coaches' decision making through the use of performance indicators (PIs). This study aimed to provide a comprehensive analysis of factors affecting running performance (RP) in soccer teams, focusing on low (LI), medium (MI), and high-speed distances (HI) and the number of high-speed runs (NHI). Data were collected from 185 matches in the Turkish first division's 2021-2022 season using InStat Fitness's optical tracking technology. Four linear mixed-model analyses were conducted on the RP metrics with fixed factors, including location, team quality, opponent quality, ball possession, high-press, counterattacks, number of central defenders, and number of central forwards. The findings indicate that high-press and opponent team quality affect MI (d = 0.311, d = 0.214) and HI (d = 0.303, d = 0.207); team quality influences MI (d = 0.632); location and counterattacks impact HI (d = 0.228, d = 0.450); high-press and the number of central defenders affects NHI (d = 0.404, d = 0.319); and ball possession affects LI (d = 0.287). The number of central forwards did not influence any RP metrics. This study provides valuable insights into the factors influencing RP in soccer, highlighting the complex interactions between formations and physical, technical-tactical, and contextual variables. Understanding these dynamics can help coaches and analysts optimize team performance and strategic decision making.

The characteristics of counterattacks in the Spanish league (La Liga) in 2021-2022.

BACKGROUND: Current studies on counterattacks are limited despite the fact that it is one of the most effective ways to score in soccer. The aim of the study was to investigate the characteristics of counterattacks in the Spanish league (La Liga) for the year 2021-2022. METHODS: The sample used in the study were 2631 counterattacks collected from a total of 380 games. The variables used were: 1) the space which the counterattack had started; 2) the number of players who participated; 3) the number of defending players; 4) the duration of the counterattack; 5) the touches to complete the counterattack; 6) the formation of both teams; 7) the way that counterattack was completed (final action); 8) the minute that the counterattack took place; and 9) which team had a home advantage. The results were analyzed using the Chi-square test. The level of significance was defined at P<0.05. RESULTS: Firstly, it appeared that most counterattacks began from the axis of the defensive zone lasting 6-15 seconds. There were 3-4 attackers participating against 4-6 defenders, using 5-9 touches. In addition, most of them took place in the 46-60 minute of the game and were completed in a shot. CONCLUSIONS: The study can help coaches and analysts to understand the characteristics of the counterattacks and adapt their training in a way to make their teams more effective, both in the attacking and defending phase.

Key Performance Indicators Predictive of Success in Soccer: A Comprehensive Analysis of the Greek Soccer League.

Previous research emphasizes the significance of key performance metrics in determining match outcomes. The purpose of this study is to enhance the understanding of success in professional soccer by analyzing the relationship between match outcomes (win, lose, draw) and various Performance Indicators extracted from the Greek soccer league, as well as to develop a regression model of success in soccer. The sample consisted of all 91 matches from the first round of the 2020-2021 season of the Greek Football League. Utilizing Kruskal-Wallis tests, significant differences were found in goals scored, shots, and shots on target, ball possession, passing metrics, touches in the penalty area, and average shot distance (p < 0.05), with winning teams having demonstrated superior performance metrics. Moreover, winning teams engaged more in positional attacks and counterattacks with shots (p < 0.05). The binary logistic regression model applied to predict match outcomes identified shots on target, counterattacks, passes metrics, offensive duels and set pieces (penalties, free kicks) as key factors influencing the likelihood of winning (p < 0.05). These findings collectively highlight the importance of effective offensive play, including goal scoring, shooting accuracy, and ball possession, in determining the outcomes of soccer matches, with the regression model offering a nuanced understanding of these relationships.

Plyometrics' trainability in preadolescent soccer athletes.

Plyometric training (PT) is a widely used method to improve muscle ability to generate explosive power. This study aimed to determine whether preadolescent boys exhibit plyometric trainability or not. Forty-five children were randomly assigned to either a control (CG, N = 21, 10.6 ± 0.5 years; participated only in regular soccer practice) or a plyometric training group (PTG, N = 24, 10.6 ± 0.6 years; participated in regular soccer practice plus a plyometric exercise protocol). Both groups trained for 12 weeks during the in-season period. The PT exercises (forward hopping, lateral hopping, shuffles, skipping, ladder drills, skipping, box jumps, low-intensity depth jumps) were performed twice a week. Preadolescence was verified by measuring Tanner stages, bone age, and serum testosterone. Speed (0-10, 10-20, 20-30 m), leg muscle power (static jumping, countermovement jumping, depth jumping [DJ], standing long jump [SLJ], multiple 5-bound hopping [MB5]), leg strength (10 repetition maximum), anaerobic power (Wingate testing), and soccer-specific performance (agility, kicking distance) were measured at baseline, midtraining, and posttraining. The CG caused only a modest (1.2-1.8%) increase in speed posttraining. The PTG induced a marked (p < 0.05) improvement in all speed tests (1.9-3.1% at midtraining and 3-5% at posttraining) and vertical jump tests (10-18.5% at midtraining and 16-23% at posttraining), SLJ (2.6% at midtraining and 4.2% at posttraining), MB5 (14.6% at midtraining and 23% at posttraining), leg strength (15% at midtraining and 28% at posttraining), agility (5% at midtraining and 23% at posttraining), and kicking distance (13.6% at midtraining and 22.5% at posttraining). Anaerobic power remained unaffected in both groups. These data indicate that (a) prepubertal boys exhibit considerable plyometric trainability, and (b) when soccer practice is supplemented with a PT protocol, it leads to greater performance gains.

Effects of Combined Horizontal Plyometric and Change of Direction Training on Anaerobic Parameters in Youth Soccer Players.

The aim of this study is to investigate whether the combination of soccer training, plyometric training (PT), and change of direction (COD) exercises would enhance anaerobic performance to a greater extent than training on its own in youth U17 soccer players. Twenty youth players participated in this study. Players were randomly separated into two groups: the control group (CG, n = 9) and the intervention group (EX), which performed extra PT and COD exercises (EX, n = 11). The duration of the training program was six weeks. Sprint 10 m, 30 m, countermovement jump (CMJ), single leg countermovement jump (CMJ right and left), squat jump (SJ), 505 test, and Illinois agility test were measured pre and post of the training program. The performance in the 505 test improved for the EX group (right leg: p = 0.031, left leg: p = 0.004). In addition, Illinois test performance increased in the EX group (2.9%, p = 0.019). The performances of the two groups differed significantly in the Illinois agility test (p = 0.001). This study supports that a short-term combined program of PT and COD exercises can improve change of direction ability in youth U17 soccer players. The lack of effect of the intervention program on sprint and jump performance may be due to the type and volume of plyometric exercises used. The results reflect the training principle of specialization of stimulus. The improvement in performance was presented in tests that had similar characteristics to training stimuli.

Muscle Strength and Hamstrings to Quadriceps Ratio in Young Soccer Players: A Cross-Sectional Study.

The aim of the present study was to examine and compare the concentric isokinetic peak torque of the knee flexors and extensors muscles, as well as their ratio, in young soccer players. Two hundred and sixty-five (n = 265) young soccer players were divided into five groups: U-12 (n = 43, mean age 11.5 ± 0.4 yrs), U-14 (n = 63, mean age 13.6 ± 0.3 yrs), U-16 (n = 64, mean age 15.4 ± 0.5 yrs), U-18 (n = 53, mean age 17.5 ± 0.4 yrs) and U-20 (n = 42, mean age 19.3 ± 0.6 yrs). Three maximal voluntary isokinetic leg extensions and flexions at angular velocities of 60, 180, and 300°·s-1, and H:Q strength ratio was determined. The largest H:Q strength ratio for all ages, with the exception of age group U-12, appears at a slow angular velocity of 60°·s-1, and the smallest H:Q ratio at a fast angular velocity of 300°·s-1. In age group U-12, at an angular velocity of 60°·s-1, the strength of the quadriceps muscle was almost twice the strength of the hamstrings. The H:Q strength ratio was smaller in age group U-12 and greater in group U-20. In age group U-12, the greatest H:Q strength ratio appeared at an angular velocity of 180°·s-1, while in the other age groups, it appeared at 60°·s-1. Strength training of hamstring muscles remains inadequate across ages. The small H:Q strength ratio in younger ages and the large H:Q ratio in older ages suggest that high-intensity training may increase the H:Q strength ratio, which, in turn, may protect the knee joint from excessive and burdensome loads.

Muscle Strength and Joint Range of Motion of the Spine and Lower Extremities in Female Prepubertal Elite Rhythmic and Artistic Gymnasts.

The purpose of this study was to investigate and compare the passive joint range of motion (PROM) and muscle strength in prepubertal rhythmic gymnasts (RGs), artistic gymnasts (AGs), and a control group (CG) of the same age. A total of 54 prepubertal girls were divided into three groups: 18 RGs (age 11.14 ± 0.7, height 142.6 ± 5.81, and body mass 31.2 ± 3.63); 18 AGs (age 11.27 ± 0.99, height 139.6 ± 5.85, and body mass 31.7 ± 3.21), and 18 school girls who are defined as CG (age 10.55 ± 0.42, height 145.33 ± 6.95, and body mass 42.1 ± 8.21) participated in the study. All athletes were elites and participated in national competitions. The CG participated only in their school physical education program. Isokinetic peak torques were measured using an isokinetic dynamometer (Cybex II) at 60, 180, and 300°·sec-1. Body mass index was greater in the CG compared to RGs and AGs (p < 0.001). PROM in cervical extension in RG was significantly higher compared to the AG and CG (p < 0.001). The athlete groups, RG and AG, showed significantly greater PROM in knee flexion (p < 0.001), hip flexion (p < 0.001), and hip abduction (p < 0.05) compared to CG. PROM in hip flexion was different between the left and right leg in RGs. The relative muscle strength of the quadriceps in the RG and AG was significantly greater compared to CG (p < 0.001 and p < 0.01 respectively). Gymnastics training in prepubertal ages can improve neuromuscular function and increase the relative muscle strength. Therefore, it is essential to note that when evaluating children within the developmental ages, especially those involved in sports, the type of muscle strength to be assessed should be specified.

Repeated sprint ability in young football players according to the position and formation of the team: the effect of a specific training program.

BACKGROUND: The aim of this study was to investigate the effect of a specific training program for 12-weeks (twice a week) on the repeated sprint ability (RSA), according to the position of the football player in the formation of the team. METHODS: Two groups of U-17 football players (experimental-group, N.=22 and control-group, N.=19) and five positions (central-defenders, wide-defenders, central-midfielders, wingers, and central-attackers) according to the position in the formation (1-4-3-3) were studied. Sexual maturation was classified according to Tanner's stages. RSA and isokinetic strength were measured pre- and after the training program. RESULTS: The results showed that in RSA were differences in the factor time in the best (F=9.316, η2=0.383, P=0.008) and mean time (F=8.002, η2=0.348, P=0.013), but there were no differences between the groups. In strength, differences were observed in the time, mostly in the extensors at the three angular velocities (60°, 180°, 300°·sec-1) with differences in the group only in the maximum force (F=8.090, η2=0.366, P=0.013). No differences between players' positions were observed. CONCLUSIONS: A specific training program seems to affect players' performance on repeated sprint ability and the specific training in the players' position according to the team formation has a positive effect on the muscle power of football players.

Correlations of passes and playing formations with technical-tactical elements during the 2022 FIFA World Cup.

BACKGROUND: This study on the 2022 Qatar FIFA World Cup examined: a) the existence of correlations between passes with other technical-tactical elements, b) the differences in technical-tactical elements in relation to team formation, and c) the characteristics of the key passes created during games. METHODS: Sixty-four games were analyzed. Match-analysis data were collected using InStat database. RESULTS: Spearman correlation revealed that the number of passes and key passes correlated with number of goals, chances and shots (P<0.05). Team ball possession was correlated with number of passes, key passes, chances, shots and the organized attacks (P<0.001). Kruskal-Wallis H non-parametric test revealed that the teams with the higher percentages of team ball possession, and the higher number of chances, shots and crosses used formations 1-4-2-3-1 and 1-4-3-3. Finally, most of the key passes performed in axis of the field and they were short low passes. CONCLUSIONS: The ability of teams to keep the possession of the ball, looking for the key pass, and final action can be a factor in the team's success. A characteristic finding of the study was the preference of groups to manifest their attack from the axis. The equal distribution of attacks between the axis and the sides of the field makes the team's offensive function more unpredictable. Also, most formations concentrate several players on the axis, making it more difficult to complete an attack from this area.

Match Running Performance Profile and Heart Rate Response in Amputee Soccer Players.

INTRODUCTION: The purpose of this study was (a) to create a profile of the running performances of male amputee soccer players in different speed zones, (b) to investigate the relationship between heart rate (HR) and running distance in two soccer matches, and (c) to study the effect of the level of amputation on the running distance covered during a match. MATERIAL AND METHODS: The participants were male amputee soccer players (n = 10, Greek, n = 5; Belgian, n = 5) who played two international, friendly matches. Distances were measured using a global positioning system, and HRs were recorded using a Polar Team Pro. RESULTS: No differences in the distances covered were observed between participants with different levels of amputation (p > 0.05). Nevertheless, there was a trend that participants with a below-the-knee amputation tended to cover longer distances in total (difference +262.3 m, Cohen's d = 0.40) and in zones 2 (+324.4 m, d = 0.79), 3 (+ 7.1 m, d = 0.65), 4 (+22.7 m, d = 0.43), and 5 (+0.4 m, d = 0.20) and less distance in zone 1 (-207.2 m, d = 0.88). They also tended to perform more accelerations (+3.9, d = 0.89) and decelerations (+4.2, d = 0.87) and had a higher mean HR (+8.4%, d = 2.04) than those with an above-the-knee amputation. Moreover, the mean HR corresponded to 83.3% of the HRmax and did not correlate with distance in any speed zone. CONCLUSIONS: It was concluded that the level of amputation might influence running performance and acute physiological response during a soccer match.

Surface Electromyographic Activity of the Rectus Abdominis and External Oblique during Isometric and Dynamic Exercises.

Exercises for the abdominal muscles are widely used in athletic activities for strength training and prevention of low back disorders. The timing and volume of muscle activation for various movements have not yet been clarified. The purpose of this research was to evaluate the surface electromyographic activity from the upper (RAU) and lower part (RAL) of the rectus abdominis and the external oblique (EO) muscles during eleven abdominal muscle strength training exercises. Thirty-five healthy male university students with a subspecialty in soccer participated in the study. They performed exercises involving isometric, concentric, and eccentric muscle contractions. The electromyographic recordings were amplified by a factor of 1000, rectified, and integrated. Mean integrated values were calculated by dividing the elapsed time for the five repetitions, to provide the mean integrated electromyographic values for each exercise. Leg movements from a long lying position showed higher activity of the rectus abdominis, compared to the EO (p < 0.001). The dynamic sit-ups showed an obvious dominant activity of the EO, compared to the rectus abdominis (p < 0.001). During eccentric exercise, higher activity was found in the RAU, compared to the RAL (p < 0.001). The results could serve as a basis for improving the design and specification of training exercises. Pre-exercises should be performed before testing abdominal muscle strength.

The effects of free weights and isoinertial resistance during semisquatting exercise on amateur soccer players' physical performance indicators: a randomized controlled study.

BACKGROUND: The aim of this study was to compare the effects of two lower extremity strengthening programs using isoinertial resistance or free weights on amateur soccer players' physical performance indicators. METHODS: Thirty-five amateur soccer players (average age 22.6±5.1 years) were randomly assigned to isoinertial group (N.=11) or free-weight group (N.=11), or control group (N.=13). The groups performed two training sessions per week for six weeks. Before and after the strengthening implementation, physical performance indicators were evaluated, including the isokinetic knee extensors and flexors' strength, power, speed, and agility. The significance level was set at P<0.05. RESULTS: The isoinertial training resistance led to an increase in the hamstrings' eccentric strength at 60°/s and 150°/s (P<0.05) compared to the free-weight resistance (P>0.05) and the controls (P>0.05). No other significant adaptations were observed in the other isokinetic strength, power, speed (10-m, P=0.052) and agility measurements (Illinois Agility Test, P=0.059). In ratio (knee flexors/knee extensors) the only differences observed were at 150°/s for isoinertial group (P<0.05). CONCLUSIONS: Isoinertial resistance training during semisquatting can enhance the hamstrings' eccentric performance and the soccer players' speed and agility compared to the classic free-weight training program, which should consider when designing strength and injury prevention programs.

Physiological and performance adaptations of elite Greco-Roman wrestlers during a one-day tournament.

The aim of this study was to determine the effects of a simulated one-day Greco-Roman wrestling tournament on selected performance and inflammatory status indices. Twelve competitive wrestlers (22.1 ± 1.3 years) completed five matches according to the official Olympic wrestling tournament regulations following a ~6% weight loss. Performance measurements, muscle damage assessment, and blood sampling were performed before and following each match. Performance and inflammatory markers were not affected by weight loss. Mean wrestling heart rate reached ~85% of maximal and lactate concentration exceeded 17 mM. Fatigue rating demonstrated a progressive rise (P < 0.05) throughout the tournament, peaking in match 4. Performance demonstrated a progressive deterioration (P < 0.05) throughout the tournament, especially in the last two matches (P < 0.05), with upper-body measures exhibiting a greater decline (P < 0.05) and remaining below baseline (P < 0.05) until the end of the tournament. Muscle damage markers increased during the course of the tournament with upper limbs affected more. Creatine kinase activity, CRP levels, IL-6 concentration, and leukocyte counts increased (P < 0.05) progressively throughout the tournament, peaking in the last two matches. Cortisol, epinephrine and norepinephrine increased (P < 0.05) after each match, but testosterone declined (P < 0.05) progressively, reaching a nadir before the last match. This inflammatory response was accompanied by a marked increase (p < 0.05) in lipid peroxidation, protein oxidation, and antioxidant status markers indicating the development of oxidative stress. These results suggest that a one-day wrestling tournament may induce significant physiological demands on wrestlers that may adversely affect their performance and inflammatory status especially during the later stages of the tournament.

The significant role of scoring from set plays in the 2018 FIFA World Cup.

BACKROUND: The aim of this study was to analyze the set-play goals achieved and VAR influence in the 2018 World Cup as well as to examine their impact on game outcome. METHODS: We analyzed 71 goals that have been scored from a set-play during the 2018 World Cup. We did not include the goals achieved during penalty process. χ2 analysis was used, and the level of significance was set at P<0.05. RESULTS: Overall, 42% of all goals came from set-plays in 64 matches of this tournament, which is on average 1.1 per match. The team that scored one or more goals via set-plays, won 71.1% of the occasions (χ2=24.368, P<0.001). Results showed that 22 goals achieved from corner kicks, and the most effective delivery area was the goal center area. Most of the goals (75.0%) from indirect free kick came from the sides, which had significant difference with the central area (χ2=4.000, P<0.05). All the goals (6) from direct free kick, were scored from the central area out of the 16.5-m box and the distance was <25 m from the goal in all of them. In total, 17 referee decisions changed after VAR reviews and 9 resulted in goals and 89% of them impact the current game outcome. CONCLUSIONS: The findings of this study highlighted the importance of scoring from set plays to game outcome. Coaches should be aware of the above findings in to order to make their teams more effective both in terms of attacking and defending a set-play situation.

The effects of an integrative training program on elite young soccer players' physical performance.

BACKGROUND: The aim of this study was to investigate the effects of a short duration and low weekly frequency integrative program on sprint, agility and jump performance in elite youth soccer players. METHODS: Twenty-eight elite youth soccer players, members of two professional clubs, playing in the U19 developmental championship participated in this study. They were divided into 2 groups: the intervention group (EG, N.=15) and the control group (CG, N.=13). The duration of the intervention program was 8 weeks with a frequency of twice per week. The performance of the participants in the 10 meters and 30 meters speed, countermovement jump (CMJ), squat jump (SJ) and agility (Illinois agility test, Arrowhead agility test) was measured at the beginning and the end of the 8-week study. RESULTS: There was no statistically significant difference in any performance measured between the two groups. CONCLUSIONS: The results of the present study indicate that the addition of allowing frequency and short duration training intervention program did not enhance the physical fitness indicators, in high-level young soccer players.

The effects of soccer training in aerobic capacity between trained and untrained adolescent boys of the same biological age.

BACKROUND: The purpose of this study was to examine the effects of soccer training on maximal oxygen uptake and anthropometric characteristics in different ages of soccer players and untrained adolescents of the same biological age. METHODS: A total of one hundred and twenty-six (N.=126) young soccer players and untrained boys throughout the developmental ages of 12 (soccer players N.=22; untrained boys = 22) 14 (soccer players N.=20; untrained boys = 18) and 16 (soccer players N.=22; untrained boys = 22) volunteered to participate in the study. Sexual maturation was classified according to Tanner's stages. Soccer players participated both in their school's physical education program and in a soccer training program, while the untrained participated only in their school's physical education program. All participants underwent anthropometric measurements and performed a maximal exercise test on a motor driven treadmill to determine maximal oxygen uptake (V̇O2max) and cardiorespiratory indices. Blood lactate (BL) concentration was determined in the 5th minute of recovery using a lactate photometer. RESULTS: The trained group showed significantly higher V̇O2max, in absolute and relative values (P<0.001), BLmax (P<0.05) and maximal respiratory exchange ratio (RERmax) (P<0.05) compared to the untrained group. Resting heart rate (HR) and systolic blood pressure were significantly lower (P<0.05) for the trained compared to untrained. CONCLUSIONS: The results of this study showed that systematic soccer training has a positive effect in the central cardiovascular system expressed as V̇O2max, HR and blood pressure.