The effects of the Video Assistant Referee system (VAR) on the playing time, technical-tactical and physical performance in elite soccer

Gaze Behaviors, Estimated Quiet Eye Characteristics, and Decision Making of Nonexpert Assistant Referees Judging Offside Events in Soccer

The study analyzed the gaze behavior and decision-making performance of 20 soccer assistant referees while judging offside events. Specifically, gaze behaviors, gaze entropy, and estimated quiet eye (eQE; defined as the last fixation prior to the attacker's ball pass) characteristics (i.e., location, onset, offset, and duration) were analyzed in relation to decision-making accuracy. Although a significant number of fixations were observed on the offside line, the highest viewing time corresponded to the ball carrier. The gaze behavior indicated a high distribution of fixations, as evidenced by high stationary gaze entropy (>90%). The assistant referees also distinguished offside from onside positions above chance. However, they displayed nonprolonged eQE on the offside line. As a result, no significant relationships were found between the eQE characteristics and decision-making accuracy. The study concludes that the absence of more functional gaze behaviors, specifically with longer eQE focused on the offside line, impaired the decision-making accuracy of nonexpert assistant referees in soccer.

From Sport Psychology to Action Philosophy: Immanuel Kant and the Case of Video Assistant Referees

The implementation of Video Assistant Referees (VARs) in 2018 has had a significant impact on the multi-billion-dollar soccer industry. As the most popular and watched sport globally, soccer's financial stakes are high, with clubs, leagues, broadcasters, sponsors, and fans heavily invested in the game. The ongoing debate surrounding the VAR system brings to light the intricate balance between preserving the authenticity of football (soccer) and harnessing technology to improve accuracy. It is crucial to strike the right equilibrium in order to uphold football's metaphorical power and sustain the timeless joy it has brought to fans throughout generations. In this context, Immanuel Kant's philosophy can offer valuable insights into the utilization of VARs in soccer. According to Kantian ethics, using VARs can be justified if it serves to enhance fairness and accuracy, aligning with the moral duties of referees. Nevertheless, it is important to consider the potential dehumanizing effects and the necessity of preserving the value of human judgment in the game. Therefore, this paper aims to explore in-depth the intricate dynamics that arise when technology is integrated into traditional practices, emphasizing the significance of critical reflection on the implications of such advancements.

The attitude of online fans: perceived value, expectation, and identification on VAR satisfaction

This study explores online fan satisfaction with the Video Assistant Referee (VAR) during the FIFA World Cup Qatar 2022. A structural equation model comprising perceived value, fan expectation, fan identification, and fan satisfaction was run. The online questionnaires were distributed among Chinese football fans. A total of 224 valid responses were received. Using indicators like Cronbach's alpha coefficient, Kaiser-Meyer-Olkin (KMO) statistic, and Bartlett's test of sphericity, the results were assessed for reliability, validity, and suitability. From the statistical results, the overall satisfaction of fans with VAR is the middle. Both fan expectation and perceived value positively affect satisfaction (p < 0.01); the path coefficients were 0.26 and 0.57. Contrastingly, fan identification exerts no significant effect on fan satisfaction (p > 0.05); and fan expectation indirectly affects fan satisfaction through perceived value (p < 0.01); the path coefficient was 0.29. The highest effect value for fan satisfaction is perceived value, followed by fan expectation. Consequently, to improve online fan satisfaction with VAR, researchers should focus on perceived value. This research contributes to a greater more comprehensive of Chinese online fans' preference towards VAR at the FIFA World Cup Qatar 2022.

Using Microtechnology and the Fourier Transform for the Analysis of Effective Activity Time in Professional Soccer

ABSTRACT

Oliva-Lozano, JM, Chmura, P, Granero-Gil, P, and Muyor, JM. Using microtechnology and the Fourier Transform for the analysis of effective activity time in professional soccer. J Strength Cond Res 37(12): 2491-2495, 2023-This study aimed to investigate the use of the fast Fourier transform (FFT) for the analysis of effective activity time in professional soccer by (a) exploring the relationship between this variable and standard external load parameters and (b) analyzing the effective activity time during official professional soccer matches. Twenty-six male players participated in the study. Each player was categorized as midfielder, central defender, full-back, wide-midfielder, or forward. Tracking systems based on inertial sensors (4 3D accelerometers, 3 3D gyroscopes, and 1 magnetometer), and global positioning systems technology were used to collect external load measures for 35 matches. Each match was analyzed considering 15-minute periods to explore the evolution of effective activity time during the matches. The extra time from each match was also included. Fast Fourier transform duration may be a representative variable of effective activity time, given the strong positive correlation with the external load variables ( p < 0.001). The linear regression analysis showed that the variables that significantly contributed to the model ( R2 = 0.97) were the total of steps and the distance covered. The mean effective activity time in soccer match play was ∼48.69 minutes. This time significantly changed depending on factors such as the period of the match ( F = 239.05; p < 0.001; ηp 2 = 0.60) or playing position ( F = 16.99; p < 0.001; ηp 2 = 0.06). The greatest effective activity time was observed for all playing positions in the 0'-15' period. However, the 60'-75' period showed the lowest effective activity times compared with the rest of the 15-minute periods for all positions except for forwards (75'-90'). From a practical standpoint, sports performance practitioners may consider these results to improve the individualization of training and match demands. Also, a more accurate indicator of exercise intensity may be obtained (e.g., multiplying the rating of perceived exertion by the effective activity time).

Waiting to score. Conversion probability and the video assistant referee (VAR) in football penalty kicks

The VAR has introduced a new element to football. Before, a decision to award a penalty kick could not be reversed. The player taking the penalty could take it relatively quickly after the referee called the foul. After the introduction of the VAR, every penalty kick decision is replayed by the VAR and also quite often reviewed on-field. As a consequence, time between the initial decision by the referee and the actual penalty kick has increased substantially. We examined the influence of the time-interval duration between the foul and the actual penalty kick on the conversion probability using a logit model. Also, we assessed the consequences of a VAR intervention, if any. We used data on all 2888 penalties awarded in top leagues in England, Spain, Germany, Italy, the Netherlands, and the UEFA Champions League, over the course of five seasons (2015/2016-2019/2020). We found that the duration between the foul and the moment the penalty is taken does not impact the conversion probability. However, whether or not the VAR intervenes with the referee's decision has a negative effect on the conversion probability of penalty kicks. Football teams and coaches should incorporate this element of uncertainty in training.

Influence of physical fitness on decision-making of soccer referees throughout the match

The purpose of this study was to analyze the relationships between physical fitness and physical performance in competition and the decision-making (successes and errors). A sample of 22 male national-level soccer referees (weight: 72.7 kg; height: 178.0 cm; age: 23.4 years) participated in this study. Physical fitness was assessed through 6 series of 40 m (velocity) and Yo-yo (aerobic) test in annual exam by Soccer Committee, physical performance was performed through the total distance covered in competition (Experiment 1), and decision-making was registered through a simulated Video Assistant Referee system (VAR) with the consensus of 2 national referees evaluating only warnings (yellow cards), expulsions (red cards), established penalties and obvious goal actions (called and no called) (Experiments 2 and 3). Results showed that physical fitness test was related with total distance (rho = 0.63, p < .01) and success rate percentage (rho = 0.74, p < .05) registered during competition. The success rate percentage, in the first half, was observed 44% successes, and in the second half, 59% successes. The number of events called was related with the physical fitness test score (R2 = 0.71, p = .035; R2 = 0.64, p = .056, respectively). As conclusion, the main finding of this study has provided insight into decision-making behavior in real competitive matches and the physical fitness was the predictor of the successful decision-making being able to determine the permanency, promotion or decrease of category.

Effective playing time affects technical-tactical and physical parameters in football

Effective playing time has been debated as a topic of major concern in football. Thus, the current experimental study aimed to investigate the effects of effective playing time on technical-tactical and physical match parameters in football. One hundred and seventy-nine male highly trained football players (aged 27.9 ± 5.1 years) from twelve teams performed two different match-play conditions: 45 min of match-play without stopping the chronometer (T45), and 30 min of match-play by stopping the chronometer every time the ball was out-of-play (T30). T30 presented a significantly higher total time (49:30 vs. 45:00 min; p = <.001; ES = 0.76), effective playing time (28:70 vs. 26:80 min; p = <.001; ES = 0.62), and stopped time (20:60 vs. 18:20 min; p = 0.003; ES = 0.38) compared to T45. Total ball possession (54.4% vs. 45.6%; p = 0.002) and 1/3 ball possession (55.3% vs. 44.7%; p = 0.018) was higher in T30 condition when compared to T45. Regarding match external load, total distance covered (4,899 vs. 4,481 m; p = <.001; ES = 0.71), moderate-speed running (607 vs. 557 m; p = 0.002; ES = 0.26) and high-speed running (202 vs. 170 m; p = <.001; ES = 0.33), high-speed activities (284 vs. 245 m; p = 0.003; ES = 0.24), accelerations (27 vs. 24; p = <.001; ES = 0.32), and decelerations (31 vs. 28; p = 0.005; ES = 0.26) were higher in T30 compared to T45. In conclusion, these findings suggest that higher effective playing time may affect technical-tactical and physical parameters during football games.

The Five-substitution Option Enhances Teams' Running Performance at High Speed in Football

The aim of this investigation was to describe how the introduction of the five-substitution option affected football teams' running performance. A comparative analysis was performed in 17 professional football teams for the 2019-2020 (up to three substitutions) vs 2020-2021 (five substitutions option) seasons in LaLiga. The five-substitution option increased the number of substitutions (from 2.9±0.1 to 4.2±1.0 substitutions/match, respectively; p<0.01, Effect Size (ES)=2.11) but it did not change the time selected for the first substitution (from 57.5±13.0 to 56.2±13.7 min; p=0.06, ES=0.1). Total running distance was similar between seasons but running distance at 21.0-23.9 km/h (from 3.0±0.4 to 3.2±0.4 km; p=0.01, ES=0.6) and at≥24.0 km/h (from 3.0±0.6 to 3.2±0.5 km; p=0.01, ES=0.3) were higher with the five-substitution option. These increases were associated with a higher distance covered by starting players (p<0.05) rather than an effect of substitute players.: With the five-substitution option, team coaches increased the number of substitutions per match which enhanced the possibilities of the team's staff to manage players' physical load. The five-substitution option allowed also increased running performance at≥21.0 km/h during the matches.

Association between Fitness Level and Physical Match Demands of Professional Female Football Referees

The aim of this study was to examine the physical demands for elite female referees during competitive matches and to evaluate the relationship between match performance and fitness levels. Seventeen female elite field referees were fitness-tested (29.0 ± 5.2 (SD) years, 163.8 ± 6.7 cm, 54.0 ± 5.1 kg, Yo-Yo Intermittent Recovery Test Level 1 (YYIR1) performance 1610 ± 319 m) and were analysed during a total of 187 football matches. Global positioning systems (GPS) were used in this research. The physical demands were significantly lower (p < 0.05) in the second half of matches compared to the first half. Regarding the acceleration-related variables, the female referees revealed a higher number of high-intensity actions in the first half compared to the second half. However, higher low-intensity demands were observed for the females referees in the second half compared to the first half in the total number of accelerations (ACC) (~70.48 n; ES = 0.61; p < 0.05) and decelerations (DEC) (~71.11 n; ES = 0.62; p < 0.05); total number of ACC in zone 1 (~85.27 n; ES = 0.70; p < 0.05) and DEC in zone 1 (Z1) (~83.98 n; ES = 0.71; p < 0.05); and distance covered accelerating and decelerating in Z1. The distance covered in YYIR1 and the performance in the repeated sprint ability test correlated with the physical demands during matches for female football referees (p < 0.05). In conclusion, this study described the physical performance profile of female football referees and differences between the first and second halves of matches were observed. The results of this study revealed positive correlations between intermittent exercise fitness levels, the repeated sprint ability performance and match performance in female football referees, and thus this information can be implemented in their training plan designs.

The effect of the video assistant referee (VAR) on referees' decisions at FIFA Women's World Cups

Video assistant referee (VAR) has been implemented in women's football, aiming to improve referees' decision-making, but its impact has not yet been analyzed. This study intended to explore how the VAR affects refereeing decisions at Fédération Internationale de Football Association (FIFA) Women's World Cup competitions. The sample includes all 52 matches played in the 2015 tournament before VAR was introduced and all 52 matches played in the 2019 competition where VAR was deployed. For each match, data on ten variables were collected: first half playing time, second half playing time, total playing time, penalties, offsides, fouls, goals, corner kicks, yellow cards, and red cards. The match variables were compared before and after VAR implementation using a Mann-Whitney U test, a Bayesian analysis, a generalized linear model, and a non-clinical magnitude-based inference. The results demonstrated that after VAR was introduced, playing time during the first half [p < 0.001, BF 10 = 547.05, Cohen's d = 1.06, 90%CI (0.71, 1.40)], the second half [p < 0.001, BF 10 = 57.09, Cohen's d = 0.91, 90%CI (0.57, 1.25)], and the entire match [p < 0.001, BF 10 = 1,120.39, Cohen's d = 1.33, 90%CI (0.97, 1.69)] increased significantly with moderate to large effect sizes, while the number of penalties, offsides, and fouls did not vary significantly neither did the number of goals, corner kicks, yellow cards, and red cards. This study has practical implications for professionals in terms of a better understanding of VAR's impact on elite women's football.

Development of the Effect of Video Assistant Referee Application on Football Parameters

The Video Assistant Referee (VAR) application is a technological development that gives referees the chance to review their critical decisions. The current study aimed to determine the effect of the VAR system in international football organizations on the game over the years. The sample of the study consists of 115 football matches, specifically 64 matches played in the 2018 FIFA World Cup and 51 matches played in the 2020 European Football Championship. In the competitions handled, the number of goals, the number of yellow cards, the number of red cards, the first half time, the second half time, the total match time, the number of penalties and the number of offsides were examined. The Mann–Whitney U test was used to compare two independent groups. As a result, in the 2020 European Football Championship, there was a decrease in the second half time (p = 0.01) and total match time (p = 0.01), and a significant increase in the number of offsides (p = 0.03) compared to the 2018 FIFA World Cup. On the other hand, there was no significant difference between the two tournaments in the variables of number of goals, number of yellow cards, number of red cards, half time and penalty shootout (p > 0.05). In light of the data obtained, it can be said that the effect of the VAR system on the spirit of the game will decrease as the share of the VAR system in the pauses during the competition decreases over the years. The data revealed in the study may be a clue to explaining why the effect of the VAR system on game dynamics and game spirit has decreased over the years. Therefore, the concerns of football stakeholders about the effects of the system on the game may gradually decrease with the arrangements made for VAR.

The Effect of the Video Assistant Referee System Implementation on Match Physical Demands in the Spanish LaLiga

The present study aimed to analyze the influence of the Video Assistant Referee (VAR) on match physical demands in the top Spanish professional football league. Match physical demand data from all the matches for two seasons (2017/2018 and 2018/2019) in the First Spanish Division (n = 1454) were recorded using an optical tracking system (ChyronHego^®). Total distance, relative total distance covered per minute, distance covered between 14–21 km·h⁻¹, distance covered between 21–24 km·h⁻¹, and distance covered at more than 24 km·h⁻¹ were analyzed; also, the number of sprints between 21–24 km·h⁻¹ and more than 24 km·h⁻¹ were taken into consideration. The times the VAR intervened in matches were also taken into account. Results showed that total distance and relative total distance significantly decreased in seasons with VAR compared to seasons without VAR. Finally, distance covered between 21–24 km·h⁻¹, distance covered at more than 24 km·h⁻¹, and the number of high-intensity efforts between 21–24 km·h⁻¹ and more than 24 km·h⁻¹ increased in seasons with VAR compared to seasons without VAR, but the differences were nonsignificant. Thus, these findings help practitioners to better understand the effects of the VAR system on professional football physical performance and to identify strategies to reproduce competition demands.

COVID-19 Confinement Effects on Game Actions during Competition Restart in Professional Soccer Players

The main objective of the present study was to compare high-intensity actions in a week of three matches before and after the COVID-19 lockdown. The observational methodology was used. This study analysed 551 professional soccer players from 22 different Spanish teams (LaLiga Smartbank 2019−2020) by a multi-camera tracking system and associated software (Mediacoach®, Spain). Variables of distances per minute and totals, travelled at High Intensity (HIR), Very High Intensity (VHIR), Sprint (HSR), player’s maximum speed, average speed, and the number of efforts in VHIR and HSR were analysed in the first and second half of the games, the full match, as well as in relation to the playing position. Players who participated in the same number of matches pre- and post-COVID-19 showed an increase in the total minutes played, p < 0.05, and small decreases in game actions, p < 0.05, with an effect size between 0.21 and 0.45, while players who participated in different number of matches pre- and post-COVID-19 showed a performance decrease, p < 0.05, with a size effect between 0.13 and 0.51; this was evident, particularly, for midfielders, p < 0.05, with a size effect between 0.39 and 0.75. The results seem to show that the playing intensity after COVID-19 confinement did not lead to large performance losses, except for midfielders who were the most involved players and showed a higher decrease in performance. The main findings of this study could provide insight to football coaches for rotations in starting line-ups and game substitutions, so as not to affect the intensity levels of the competitions.

Fans’ Perceptions towards Video Assistant Referee (VAR) in the English Premier League

The video assistant referee (VAR) in association football was developed to help on-field referees judge potentially game-changing decisions correctly by reviewing video evidence in real time. VAR was implemented by the English Premier League (EPL) ahead of the 2019/20 season. Despite its potential benefits, VAR also presents the risk of not being well perceived by fans. This article aims to investigate fans’ perceptions towards VAR in the EPL. Total of 1350 EPL fans from different age groups above 18 years old completed an online survey on their opinion of VAR and changes they felt would make VAR better. The majority of fans were happy for VAR to continue being used in the EPL, but expressed that changes need to be made in terms of how VAR is being used by on-field referees and to assess certain situations. All age groups were generally positive towards the idea of using technology in the EPL to support referee decisions and provide more information to in-stadium fans, but younger age groups showed significantly more positive perceptions than their older counterparts. Implications include advice for the EPL to make changes according to fans’ opinions and to develop frameworks for making changes with fans as stakeholders in mind.

A Longitudinal Exploration of Match Running Performance during a Football Match in the Spanish La Liga: A Four-Season Study

This study aimed to analyze and compare the match running performance during official matches across four seasons (2015/2016-2018/2019) in the top two professional leagues of Spanish football. Match running performance data were collected from all matches in the First Spanish Division (Santander; n = 1520) and Second Spanish Division (Smartbank; n = 1848), using the Mediacoach® System. Total distance and distances of 14-21 km·h-1, 21-24 km·h-1, and more than 24 km·h-1, and the number of sprints between 21 and 24 km·h-1 and more than 24 km·h-1 were analyzed. The results showed higher total distances in the First Spanish Division than in the Second Spanish Division (p < 0.001) in all the variables analyzed. Regarding the evolution of both leagues, physical demands decreased more in the First Spanish Division than in the Second Spanish Division. The results showed a decrease in total distance and an increase in the high-intensity distances and number of sprints performed, although a clearer trend is perceived in the First Spanish Division (p < 0.001; p < 0.01, respectively). Knowledge about the evolution of match running performance allows practitioners to manage the training load according to the competition demands to improve players' performances and reduce the injury rate.

Video assistant referees (VAR): The impact of technology on decision making in association football referees

The use of technology has been proposed to improve decision-making in sport officials. The implementation of the video Assistant Referee (VAR) in association football is one example of how technology can be used to assist decision making, although its impact remains unknown. In 2195 competitive football matches across 13 countries, the VAR conducted 9732 checks for potential match-changing incidents, with the median duration of a check being 22 seconds. The checks resulted in a total of 795 reviews, with a median duration of 62.0 s for on-field reviews (N = 534) and 15.0 s for VAR-only reviews (N = 261).We report that the predictive odds for making the correct decision after VAR intervention were significantly higher than for the initial referee's decision, with accuracy increasing from 92.1% to 98.3%. Findings have implications for the current debate about the introduction of technology in association football and may help set guidelines regarding the use of technology across other sports and professional domains.