International Soccer Players Research Articles

Soccer Bubble: Is There a Speculative Bubble in the Price of International Soccer Players?

An exponentially increasing trend of players’ registration prices has taken place since 2012, and we test the hypothesis that this may be a speculative bubble, using a structural break test (Chow test) on a data set of international soccer players' registration prices, that ranges from 2007 to 2019. The test confirms the presence of an abrupt change in the trend of these prices since the year 2012, both for the whole data set and for subgroups based on the types of competition considered (Champions League, Europa League, and residual) and on the age of the players. We surmise that a possible root at the base of this trend is the need for soccer teams to cope with the Fair Play regulation, which has taken place exactly in the same years, and caused an excess of players’ trading as a means to comply with the obligation for teams to balance their books over time.

A comparison in knee flexor and extensor strength following ACL reconstruction in international, male soccer players receiving patellar tendon or hamstrings grafts.

The aim of this study was to compare knee extensor and flexor strength recovery following anterior cruciate ligament (ACL) reconstruction between bone-patellar tendon-bone (BPTB) and hamstring tendon (HT) grafts in international male soccer players undergoing comparable 6-month rehabilitation programmes. Seventeen players underwent ACL reconstruction with either an autogenous BPTB graft or HT graft. Knee extensor and flexor peak torques were measured at 3 months and 6 months in the injured and contralateral legs following surgery using isokinetic dynamometry. The moderate-large asymmetries in knee extensor peak torque between legs at 3 months across graft types (BPTB: p = 0.002, g = -0.94; HT: p = 0.02, g = -0.55) were reduced to trivial asymmetries at 6 months (BPTB: p = 0.30, g = -0.19; HT: p = 0.40, g = -0.16), with a non-significant difference in limb symmetry index (LSI) between grafts at 6 months (p = 0.62, g = -0.24). Similarly, moderate-large asymmetries in knee flexor peak torque between legs at 3 months across graft types (BPTB: p = 0.13, g = -0.50; HT: p = 0.01, g = -0.97) were reduced to trivial-small asymmetries at 6 months (BPTB: p = 0.25, g = 0.18; HT: p = 0.01, g = -0.47); however, a superior LSI was evident with BPTB compared to HT grafts at 6 months (p = 0.007, g = 1.43, large). Strength and conditioning professionals working with soccer players who are rehabilitating from ACL reconstruction after receiving a HT graft should give adequate attention to delivering suitable hamstring exercises that ensure optimal strength restoration.

The physical demands of the match according to playing positions in a South African Premier Soccer League team.

Evidence indicates that international soccer players cover a total distance of between eight and 14 km in a match. Approximately 80 - 90% of this distance constitutes low-intensity actions, and about 10 - 20% is high-intensity. These data are influenced by playing position, formation, league standard, and national differences in different countries. To quantify the physical demands of competitive matches on the different playing positions in a South African Premier Soccer League team. A descriptive study design included 21 players on the same team. Data were collected over 23 official matches during the 2019/2020 season using PlayerTek GPS devices (10Hz). The data collected included total distance covered, high-intensity running distance, power plays, top-end speed, and distance per minute. Statistical differences were evident only in the high-intensity running distance and power plays. The centre-forwards (p<0.001), attacking central midfielders (p=0.006), and full-backs (p=0.01) covered the most high-intensity running distance (p<0.001) than centre-backs. The attacking central midfielders and centre-forwards recorded more power plays than the centre-backs. Total distance (p=0.01), power plays (p=0.004) and distance per minute (p=0.001) were lower in the second half than in the first half of the match. Centre-forwards performed more high-intensity actions, whereas the centre-backs sprinted less than all the other positions. These data provide insight into the positional differences that exist and could help coaches to prescribe position-specific training programmes.

Match Exposure, Consecutive Match Number, and Recovery Days Affect Match Running During International Women's Soccer Tournaments.

Brown, G, Massard, T, Wignell, T, McCall, A, and Duffield, R. Match exposure, consecutive match number, and recovery days affect match running during international women's soccer tournaments. J Strength Cond Res 38(3): 577-583, 2024-To determine the influence of tournament-specific factors (match exposure, consecutive matches, and days between matches) on match running in women's international soccer players (footballers), 28 players from 1 national team were observed over 4 international tournaments using 10 Hz global positioning system units. Linear mixed models with a forward selection approach were used to analyze the collective effect of tournament-specific factors of match exposure (playing time), consecutive matches (count), days between matches (count) and time on pitch on relative (min -1 ) match running metrics (total distance, high-speed running, very high-speed running, accelerations, and decelerations), and the change in these metrics between halves. The significance level was set at p < 0.05. Days between matches were included in the final models for total distance ( p < 0.0001), high-speed running ( p = 0.002), very high-speed running ( p = 0.025), and change in accelerations ( p < 0.0001) and decelerations ( p = 0.002). Prior match exposure was included in the models for total distance ( p = 0.021), change in total distance ( p < 0.0001), and change in high-speed running ( p = 0.0008). Consecutive match number was included in the model for deceleration ( p = 0.030), change in very high-speed running ( p = 0.016), change in acceleration ( p < 0.0001), and change in deceleration ( p < 0.0001). Time on pitch was included in the final total distance ( p = 0.044), high-speed running ( p < 0.0001), acceleration ( p < 0.0001), and deceleration ( p = 0.0003) models. Overall, reduced match running throughout tournaments was associated with increased time on pitch and ≤3 days between matches. Increasing match exposure and more time between matches minimizes reductions in match running between halves. Practitioners can use these variables to inform player monitoring during international soccer tournaments and on return to clubs.

The Effect of the Quadriceps Muscle Fatigue After an ISOTONIC Contraction on Some Kinematic Variables and the Accuracy of Soccer Players’ Performance of the Corner Kick

Fatigue in muscles is a reason for the low skill performance of soccer players so this study sought to find out the effect of the quadriceps muscle fatigue resulting from an isotonic contraction on some kinematic variables and the accuracy of soccer players’ execution of the corner kick. A test for the accuracy of the corner kick and the leg press exercise was used on a sample of 8 international soccer players, and their means were as follows: age: 26.8 ±2.3 years, height: 174 ±12 cm, mass: 71 ±6 kg, training age: 14.6 ±1.8 years. The performance of the corner kick test was videotaped by three cameras and Kinovea program for kinematic analysis was used. The results showed a negative effect of the quadriceps muscle fatigue after isotonic contractions on kinematic variables and on the accuracy of corner kicks. The study results point to the necessity of enhancing the ability of soccer players in terms of endurance of muscle strength in the quadriceps muscle to the highest possible extent due to the importance of that element in their skillful performance, including the accuracy of the implementation of corner kicks.

How one gesture curbed ethnic discrimination

AbstractMembers of ethnic and racial minorities across North America and Europe continue to face discrimination, for instance, when applying for jobs or seeking housing. Such unequal treatment can occur because societies categorize people into groups along social, cultural, or ethnic and racial lines that seemingly rationalize differential treatment. Research suggests that it may take generations for such differences to decline, if they change at all. Here, we show that a single gesture by international soccer players at the World Cup 2018 – followed by an extensive public debate – led to a measurable and lasting decline in discrimination. Immediately after the galvanizing event, invitation rates to view apartments increased by 6 percentage points for the migrant group represented by the players, while responses to the native population did not change noticeably. We demonstrate that anti‐immigrant behaviour can disband rapidly when the public receives messages challenging the nature of ethnic and racial categories while sharing a common cause.

Soccer Bubble: Is There a Speculative Bubble in the Price of International Soccer Players?

Soccer Bubble: Is There a Speculative Bubble in the Price of International Soccer Players?

The Efficacy of Heat Acclimatization Pre-World Cup in Female Soccer Players.

The efficacy of a 14-day field-based heat acclimatization (HA) training camp in 16 international female soccer players was investigated over three phases: phase 1: 8 days moderate HA (22. 1°C); phase 2: 6 days high HA (34.5°C); and phase 3: 11 days of post-HA (18.2°C), with heart rate (HR), training load, core temp (Tc), and perceptual ratings recorded throughout. The changes from baseline (day−16) in (i) plasma volume (PV), (ii) HR during a submaximal running test (HRex) and HR recovery (HRR), and (iii) pre-to-post phase 2 (days 8–13) in a 4v4 small-sided soccer game (4V4SSG) performance were assessed. Due to high variability, PV non-significantly increased by 7.4% ± 3.6% [standardized effect (SE) = 0.63; p = 0.130] from the start of phase 1 to the end of phase 2. Resting Tc dropped significantly [p < 0.001 by −0.47 ± 0.29°C (SE = −2.45)], from day 1 to day 14. Submaximal running HRR increased over phase 2 (HRR; SE = 0.53) after having decreased significantly from baseline (p = 0.03). While not significant (p > 0.05), the greatest HR improvements from baseline were delayed, occurring 11 days into phase 3 (HRex, SE = −0.42; HRR, SE = 0.37). The 4v4SSG revealed a moderate reduction in HRex (SE = −0.32; p = 0.007) and a large increase in HRR (SE = 1.27; p < 0.001) from pre-to-post phase 2. Field-based HA can induce physiological changes beneficial to soccer performance in temperate and hot conditions in elite females, and the submaximal running test appears to show HRex responses induced by HA up to 2 weeks following heat exposure.

Vertical Force-velocity Profiling and Relationship to Sprinting in Elite Female Soccer Players.

Explosive actions are integral to soccer performance and highly influenced by the ability to generate maximal power. The purpose of this study was to investigate the relationship between force-velocity profile, jump performance, acceleration and maximal sprint speed in elite female soccer players. Thirty-nine international female soccer players (24.3±4.7 years) performed 40-m sprints, maximal countermovement jumps and five loaded squat jumps at increasing loads to determine individual force-velocity profiles. Theoretical maximal velocity, theoretical maximal force, maximal power output, one repetition maximal back squat and one repetition maximal back squat relative to body mass were determined using the force-velocity profile. Counter movement jump, squat jump and maximal power output demonstrated moderate to large correlation with acceleration and maximal sprint speed (r=- 0.32 to -0.44 and -0.32 to -0.67 respectively, p<0.05). Theoretical maximal velocity and force, one repetition maximal and relative back squat demonstrated a trivial to small relationship to acceleration and maximal sprint speed (p>0.05). Vertical force-velocity profiling and maximal strength can provide valuable insight into the neuromuscular qualities of an athlete to individualize training, but the ability to produce force, maximal power, and further transference into sprint performance, must be central to program design.

Age-Group Differences in Reactive Strength and Measures of Intra-day Reliability in Female International Footballers

The aim of this present study was to compare the reactive strength index (RSI) characteristics and trial to trial reliability of U17, U19 and Senior female international soccer players. Fifty – seven elite female soccer player participated in the study, (age: 18.1 + 3.1 years; height: 167.5 + 6.3 cm; weight: 61.84 + 7.7 kg). Participants performed 3 maximal repetitions of the 10/5 repeated jump test (10/5RJT) following a specific warm-up and familiarisation protocol. Senior players possessed higher levels of RSI with large effect size present when compared with the U17 (P= 0.043, ES = .97) and U19 (ES = 0.85) age groups. Trivial differences (ES = 0.17) in RSI existed between the U17 and U19 age categories. Trial-to-trial analyses demonstrated 10/5 RJT RSI to possess adequate levels of reliability with a range of mean coefficients of variance (CV) of 3.1 – 7.3 % and intraclass correlation (ICC) between 0.95 – 0.98 present across all three age groups. However, large variations in the between – athlete CV for RSI were revealed ranging from 1 – 27 %, 0.4 – 10.3%, and 1 – 7 % for U17, U19 and senior age groups respectively. These results suggest that age group can distinguish reactive strength capabilities. In addition, female international footballers with higher levels of RSI appear to produce more reliable measures of RSI via the 10/5 RJT.

Are There Differences in Concentric Isokinetic Strength Perfor-Mance Profiles between International and Non-International Elite Soccer Players?

The purpose of this study is to evaluate the differences in concentric isokinetic strength characteristics of the knee extensor and knee flexor musculature between international (IL) and non-international level (N-IL) soccer players. The second aim is to establish strength symmetry status in knee muscles for dominant (DL) and non-dominant (NDL) legs for both within and between groups. 100 male top elite soccer players (IL: n = 36, age = 27.5 ± 3.4 years and N-IL: n = 64, age = 27.7 ± 6.4 years) underwent concentric isokinetic strength tests, using a Biodex System 3 dynamometer. Results indicate that statistically significant differences between groups were noted for peak torque of hamstrings (PT-H), hamstrings/quadriceps (H/Q) ratio, and total work of hamstrings (TW-H), where mean values for the IL were similarly higher than for the N-IL group (p = 0.006, p < 0.001, and p = 0.012, respectively). Our results also showed statistically significant differences for peak torque of quadriceps (PT-Q), PT-H, total work of quadriceps (TW-Q) and TW-H between legs, where mean values noted for the DL were higher than for the NDL for both groups (p = 0.021, p < 0.001, p = 0.006, and p = 0.004, respectively). Additional results show that IL players presented more symmetrical strength between legs than N-IL. The results of this study indicate that that the greatest differences in isokinetic strength performance across players at different soccer levels relate to the hamstring muscle. As a result, systematic strength training of these muscle groups is strongly recommended.

The developmental and professional activities of female international soccer players from five high-performing nations

ABSTRACT We study the developmental and professional activities engaged in by 86 female adult soccer players from the senior national teams of Australia, Canada, England, Sweden, and the United States of America. Players completed the Participation History Questionnaire (PHQ) to elicit the amount and type of activities engaged in across their developmental and professional years, including milestones, soccer-specific activity and engagement in other sport activity. Greater specialisation than diversification characterised their childhood developmental activities, including all players starting in soccer in childhood and accumulating more hours in soccer activity than other sports during this period. However, interindividual variation further characterised these childhood activities, with a proportion of players diversifying into other sports and/or soccer play to a greater or lesser degree during childhood when compared to the other players. The amount of coach-led soccer practice increased for all players across their development culminating in an average of 15–16 h/wk across a 40-week season in early adulthood. In contrast, the amount of engagement in other sports and soccer peer-led play varied between players but generally decreased across adolescence to negligible amounts in late adolescence. Findings are commensurate with the deliberate practice framework and early engagement.

Field Methods to Estimate Fat-free Mass in International Soccer Players.

Based on the high financial and logistical costs associated with the assessment of body composition with dual-energy X-ray absorptiometry (DXA), this study determined which field method has the best correlation with DXA data, and developed an equation to estimate fat-free mass (FFM) using the field anthropometric data in international soccer players. A total of 17 international soccer players participated in this study. DXA values provided a criterion measure of FFM. Correlation coefficients, biases, limits of agreement, and differences were used as validity measures, and regression analyses were used to develop the prediction equation. All field methods used to obtain FFM data showed positive correlations (r from 0.90-0.96) with DXA. Only the equation developed by Deurenberg et al. [6] showed no differences from DXA with a low bias. The main strength of this study was providing a valid and accurate equation to estimate FFM specifically in international soccer players.

Phenomenal decision-making in elite soccer: making the unseen seen

ABSTRACTPurpose: Decision-making research in soccer is dominated by a methodological dichotomy between experimental research approaches and ecological research approaches. The aim of this paper is to expand the methodological discussion on decision-making in soccer by demonstrating the utility of a phenomenological analysis of decision-making. This paper responds to calls for future research on decision-making to address the lack of studies which include the athlete’s perspective and adds to the growing body of sporting literature which examines the athlete’s subjective or lived experience of their sporting domain as a means to explore a specific aspect of sporting performance.Methods: To analyse the live decision-making moment in elite soccer we utilised self-confrontational interviews, which involved the combination of audio-visual data and a phenomenological elicitation interview as a means to elucidate the expert player’s pre-reflexive experiences during the decision-making moment. An expert sample included senior international female soccer players (n = 10).Results / Conclusion: Findings highlight the capacity of a phenomenological methodology to capture the complex interaction between the simultaneous processes underpinning the decision-making moment, to enhance current research methodologies of decision-making and to contribute to future research perspectives on decision-making.

A Comparative Look at Aggression and Self-esteem among Turkish versus International Super and Premier League Soccer Players Playing in Turkey

This study comparatively examines aggression and self-esteem among Turkish versus international (foreign) male super and premier league soccer players playing for the Turkish Football Federation. A sample population of one hundred twelve (112) out of all possible athletes of the above description has been featured in this study. Both Coopersmith’s Self-Esteem Inventory (1974) (adapted into Turkish by Turan & Tufan (1987)), as well as an aggression inventory developed by Ipek Ilter Kiper[1]—and which include reactive-expressive, reactive-inexpressive, and proactive-relational aggression — were used as data collection tools. T-tests, alongside single direction variance analysis were used for data analysis. Accordingly, meaningful correlations were found among super versus premier league soccer players when it came both to inexpressive and expressive aggression as well as self-esteem. However, no meaningful correlation had appeared to emerge upon comparing the point scores between international versus Turkish soccer players for all three sub-types of aggression, for aggression on whole, and for self-esteem. On the contrary, a sound correlation was found between expressive aggression and the marital status of all of the players in question. Two further meaningful correlations had been identified with respect to self-esteem and the age of all of the players, as well as with respect to expressive aggression and players’ education levels. In contrast, no meaningful correlation had emerged out of the total point scores for all three subtypes of aggression, for aggression on whole, and for self-esteem on whole versus players’ hand and foot dexterities. Nevertheless, one final correlation had been established between players’ sense of expressive aggression versus what position they played on.

Salivary IgA and pre-training wellness status across an international soccer qualifying and finals campaign (Euro 2016)

The aim of this investigation was to examine the salivary IgA (salivary immunoglobulin-A), RPE and pre-training wellness status across an international qualification and finals campaign. Data were collected for 37 elite male international soccer players (mean ± standard deviation, age: 24.9 ± 3.3 years; height: 182.5 ± 6 cm; mass: 73.1 ± 6.2 kg; positions: Goalkeeper, Center Defender, Wide Defender, Center Midfield, Wide Forward, and Center Forward) across two consecutive seasons. Training RPE, wellness questionnaire, and saliva samples were taken throughout the Euro 2016 qualifying and finals campaign. Results revealed how Readiness and Total Wellness (r = −0.28, p &lt; 0.05) correlated to salivary immunoglobulin-A, in the day preceding games (MD−1). No correlation between wellness and salivary immunoglobulin-A was observed in MD−4; however, Energy correlated to salivary immunoglobulin-A between MD−3 and MD (from r = −0.18 to −0.22, p &lt; 0.05), with significance observed between RPE and Total Wellness r = −0.22 (Total Wellness), r = −0.21 (Energy), r = −0.17 (Readiness), and r = −0.24 (Lower Body Soreness) (p &lt; 0.05). It can be concluded from the data that all wellness markers except Sleep correlated to salivary immunoglobulin-A. Furthermore, it was revealed that Energy appeared to be the greatest wellness assessment marker related to salivary immunoglobulin-A. As a result of this specific investigation, it can be confirmed that the use of a pre-training subjective Wellness questionnaires may be a useful tool to monitor individual mucosal immunity response to training.

SUBJECTIVE SLEEP QUALITY IN ELITE WOMENS INTERNATIONAL SOCCER PLAYERS PRIOR TO AN INTERNATIONAL MATCH

BackgroundSleep has been found to have many recuperative and restorative effects on an athlete's recovery and preparation for a match. In international soccer it is common that players have to...

USING MOBILE DEVICES TO MONITOR HEALTH AND WELLBEING, IN AND OUT OF COMPETITION, IN ELITE INTERNATIONAL WOMENS SOCCER

BackgroundIn recent years mobile devices (smartphones) have been used to gather subjective and objective international athlete health and wellbeing data via athlete self-report measures (ASRM).ObjectiveTo implement a system of ASRM...

A Test Battery to Identify Elite Talent Among Youth International Soccer Players

Methods of assessing soccer players’ performance have developed significantly in recent times. The fitness profiles and skill levels of a prospective elite soccer player is a valuable resource for coaches in the process of identifying talent. PURPOSE: The aim of this study was to use a battery of validated sport-specific tests to identify elite talent among youth international soccer players in Hong Kong. METHODS: International soccer players from the Hong Kong Football Association (HKFA) youth academy (U-19) squad took part in this study. Following two familiarization trials using the Loughborough Soccer Passing Test (LSPT), the exercise protocol consisted of a standardized 10 minute dynamic warm-up, followed by baseline LSPT measurements. Then, each participant completed a validated, soccer-specific, repeated-sprint ability test (RSA) in order to induce game-specific, short-term fatigue. Upon completion of the RSA, each participant was immediately re-tested on the LSPT. Each participant then completed a vertical jump (VJ) test and finally, the yo-yo intermittent recovery test level 2 (YYIR2). Heart-rate (HR) monitors were used to monitor exercise intensity. Data was analysed using SPSS (v. 20). RESULTS: 30 youth (U-19) HKFA international squad members took part in this study (mean ± SD: age 18 ± 0.8y; height 1.73 ± 0.5m; body mass 64.3 ± 8.5kg). The re-test scores of the LSPT indicated that 6 of participants (20%) maintained their skill performance, in spite of a significantly elevated heart rate induced by the RSA; i.e. no significant differences were observed in any of the movement (mov), penalty (pen) or total (tot) time taken to complete the LSPT between the pre- and post-RSA scores (Mov: pre 48.2 ± 2.9s, post 48.0 ± 2.1s; Pen: pre 5.9 ± 7.5s post 6.5 ± 8.4s; Tot: pre 54.1 ± 8.4s, post 54.5 ± 10.6s, p > 0.05). Vertical jump scores were 106.6 ± 8.5 cm. Participants completed 10.9 ± 2.9 stages of the YYIR2, with those above the 86 percentile completing greater than 13.5 stages. CONCLUSIONS: This study highlights the ability of validated sports-specific tests to effectively identify elite level talent among international youth soccer players. Each of LSPT, RSA and YYIR2 scores proved sensitive in separating the top quartile of elite level players from the remainder of the squad, while the VJ did not.

The effects of ball possession status on physical and technical indicators during the 2014 FIFA World Cup Finals

ABSTRACTThis study examined the effect of high- (HPBPT) and low-percentage ball possession (LPBPT) on physical and technical indicators during 2014 FIFA World Cup matches. This would enable a regression model to be constructed to further understand the impact of different ball possession (BP) strategies on match performance. Data were collected from 346 international soccer players using a multiple-camera computerised tracking system. Although players in HPBPT covered lower distances (P < 0.01) in total and at low speed compared to LPBPT, this produced a trivial effect size (ES). However, they covered similar distances (P > 0.05) at medium and high speeds. Players in LPBPT covered more distance without BP but less with BP than HPBPT (P < 0.01; ES large). All positions in LPBPT spent less time in the opposing half and attacking third than the players in HPBPT (P < 0.01; ES small–moderate), but all positions in HPBPT completed more short and medium passes than LPBPT (P < 0.01; ES moderate). Players in HPBPT produced more solo runs into the attacking third and penalty area than LPBPT (P < 0.05, ES small). The equation to predict BP from physical and technical indicators highlighted the importance of distances covered (total, with and without BP), time spent in the attacking third and successful short passes during matches. In practical terms, high or low BP does not influence the activity patterns of international matches although HPBPT spend more time in offensive areas of the pitch.