How the COVID-19 Pandemic has Changed the Game of Soccer

Impact of COVID-19 on football attacking players' match technical performance: a longitudinal study

This study examined the impact of COVID-19 on 28 indicators of match technical performance (MTP) for football attacking players upon their return to play. Analyzing data from 100 players in the Big Five European football leagues, covering 1500 matches each before and after COVID-19 over 3 years (2020-2023), revealed significant differences in 76% of players' MTP indicators. Notably, 14 indicators, particularly the five indicators linked to scoring, significantly decreased post-COVID-19. On average, players needed 3.09 matches to regain pre-infection MTP levels. The impact varied across player groups, with those in the elite group showing a milder effect; they required an average of 2.64 matches for recovery, compared to the control group's 3.55 matches. We found that, with increasing age, the majority of players' MTP indicators did not exhibit significant changes, both before and after they contracted COVID-19. In conclusion, the study highlighted the negative impact of COVID-19 on football attacking players' MTP. Players in the elite group experienced fewer adverse effects than those in the control group. This insight assisted coaches and managers in evaluating the impact of COVID-19 and similar virus-induced illnesses on players' MTP, enabling them to formulate training regimens for recovery and specific match tactics upon players' return to play.

Impact and control of the COVID pandemic in an elite sports club: Real Madrid

The incidence and risk factors for poor outcome in patients with COVID are well known, as are the protective measures in high-risk populations. In contrast, the epidemiological and clinical behavior of this disease in the population of elite athletes who are the paradigm of good health is poorly understood. Data on COVID in athletes are scarce and have focused preferentially on the consequences on sports performance of confinement measures and on the pathophysiological risks of infected athletes. Real Madrid is a large elite sports institution with facilities in the City of Madrid where 600 athletes train daily. The incidence of COVID during a study period of 671 days of observation in athletes, professional or amateur, working in the institution has been 0,74 per 1,000 days of exposure. The disease has been asymptomatic or oligosymptomatic in all athletes and did not require any hospital admissions. The different teams did not have to suspend any of its sportive commitments for COVID during the study period and there was no evidence of outbreaks of internal transmission between members of the different teams.

Seasonal analysis of match load in professional soccer players: An observational cohort study of a Swiss U18, U21 and first team

The aim of this study was to quantify and compare various external match load measures in three age groups and leagues in male soccer (U18 in highest league of their age group vs U21 in fourth highest league vs first team in highest league). In this retrospective observational cohort study accelerations, decelerations, absolute and relative high-speed running as well as sprint distance, dynamic stress load, explosive distance, high intensity bursts total distance, high metabolic load (HML) distance, speed intensity, total distance, total time, and total loading were assessed in 416 individual player matches of 59 players. All these external load measures showed large inter-individual variability. At a group level, one-way ANOVAs or Kruskal-Wallis tests revealed statistically significant differences between the three teams for all measures analyzed (all p < 0.05), except accelerations. The first team displayed statistically significant higher dynamic stress load, explosive distance, HML distance, speed intensity, total distance and total loading compared to the two youth teams (all p < 0.05). The U18 featured statistically significant higher number of decelerations, absolute and relative high-speed running distance, high metabolic load distance, speed intensity, relative sprint distance, total distance, and total time than the U21, while for U21 higher dynamic stress load was observed than for U18 (all p < 0.05). Based on our data we conclude a routinely monitoring of match loads of different age groups and competitive settings to be required to 1) provide an indication of what players need to be prepared for, 2) track the athletic and match evolution, and 3) individually tailor training programs allowing players to fulfill the short- and long-term sport-specific requirements.

The influence of removing home advantage on the Chinese Football Super League

BACKGROUND

Due to the COVID-19 pandemic, the 2020 season Chinese Super League (CSL) was held in neutral venues, this study aims to analyse the impact of removing home advantage (HA) in CSL.

METHOD

240 games of the CSL 2019 season (home and away double round-robin system) and 160 games of the 2020 season (in neutral venues) were analysed. 27 technical and tactical performance indicators were involved as dependent variables. A multiple linear regression model was established to analyse the influence of removing HA on the performance indicators.

RESULTS

After moving from home stadium to neutral venue in 2020 season, goal, shot, shot on target, shot from outside box, shot from inside box, shot on target from inside box, corner kick, key pass, cross, breakthrough, tackle decreased significantly (p < 0.05), while yellow card and foul increased steeply (p < 0.05). Comparing with playing away match, in neutral venue, free kicks and pass accuracy enhanced radically (p < 0.05), while tackle, clearance and block shot dropped noticeably (p < 0.05).

CONCLUSION

When removing HA and playing in the neutral venue, teams' performance dropped significantly. This study confirmed the positive impact of HA on the teams' performance and may help elite football teams make proper playing strategies regarding different match locations.

Exploring the impact of the COVID-19 pandemic in Euroleague Basketball

The aim of this study was to understand how training and playing conditions during the COVID-19 pandemic affected the performance of Euroleague Basketball players. Using a non-participant observation analysis, the study compared the seasons before the lockdown (2018-2019 and 2019-2020; pre-pandemic) with the season after restart (2020-2021; pandemic). Paired t-tests and Wilcoxon tests were applied for variables with normal and non-normal distributions, respectively. The results revealed significant changes (p < 0.05) in several offensive and defensive performance-related variables during pandemic times (without attendance): free throw attempts, free throw percentage, turnovers, three-point attempt rate, fouls (small effect sizes, ESs), points, and possessions (trivial ES). The pre-pandemic HA (70%) significantly decreased after the lockdown, with games played with no crowd (∼51%; p = 0.018, large ES). The one-sample t-test showed that the HA after the COVID-19 interruption was not significantly greater than 50%, indicating that the HA did not endure during the pandemic condition. Although significant differences between home and away teams were found for most performance-related variables (excepting turnovers) in both pre-pandemic and pandemic conditions, variations of the relative HA were only significant for free throw attempts (large ES), points (medium ES), and turnovers (medium ES). The results of this study showed that performance variables were affected by the COVID-19 lockdown. Thus, these findings may help coaches, players, and referees to counteract unwanted competitive events and improve their overall performance, regardless of the contextual/situational circumstances encountered.

Two Years of COVID-19 Pandemic: How the Brazilian Serie A Championship Was Affected by Home Advantage, Performance and Disciplinary Aspects

As a result of the COVID-19 pandemic, the Brazilian Serie A championship was played without crowds in 2020 and partially in the 2021 season. We verified if the home advantage (HA) was different between the 2018, 2019, 2020, and 2021 seasons. We also compared the HA, performance, and disciplinary aspects between the rounds with or without crowds and verified the association between the number of absent athletes because of health protocols and the HA in the 2020 and 2021 seasons. We calculated the HA using the Pollard method. The performance aspects were goals, corners, shots, and ball possession, and the disciplinary aspects were fouls, yellow cards, and red cards. The HA was higher in the 2018 season compared with the other seasons. The rounds with crowds showed higher HAs than the two previous seasons and the teams had more shots and scored more goals than in the rounds without crowds. There were 457 athletes in the 2020 season and 123 athletes in the 2021 season who were absent because of health protocols, and there was no association between absence and HA. The COVID-19 pandemic affected soccer in the two last seasons in different ways in the Brazilian Serie A championship.

A complete season with attendance restrictions confirms the relevant contribution of spectators to home advantage and referee bias in association football

Background

Due to the unfortunate pandemic situation, the phenomena of home advantage and referee bias in sports have recently received a particular research attention, especially in association football. In this regard, several studies were conducted on the last portion of the 2019-20 season: the majority of them suggests a reduction-but not the elimination-of the two phenomena, with some exceptions in which no reduction was found or, at the other extreme, the phenomena were not observed at all.

Methods

The continuation of the pandemic made it possible to replicate the previous studies considering the complete 2020-21 season, thus with the important added value of having a fully balanced home/away schedule-and a higher number of matches-in the various leagues. In particular, the sample of the present study consisted of 3,898 matches from the first and second divisions of the UEFA top five ranked countries, that is, England, Spain, Italy, Germany, and France. For the home advantage, the following variables were examined: distribution of matches outcomes and home advantage for points (also for previous seasons from the 2014-15 one); ball possession; total shots; shots on goal; and corner kicks. Instead, for he referee bias, the following variables were examined: fouls; yellow cards; red cards; penalty kicks; and extra time. Chi-square tests were used to compare the distribution of matches outcomes, and t-tests to compare home vs. away data for the other variables in the 2020-21 season; Bayesian and equivalence analyses were also conducted.

Results

The main results are as follows: (a) the distribution of matches outcomes in the 2020-21 season was significantly different from that of the last five complete seasons with spectators (Chi-square = 37.42, df = 2, p < 0.001), with fewer home victories and more away victories; the resulting values of the home advantage for points were 54.95% for the 2020-21 season, and 59.36% for the previous seasons; (b) for the other home advantage variables, a statistically significant overall advantage for the home team emerged; nevertheless, the strength of the differences between home and away teams was generally small (0.09 < Cohen's d < 0.17), and the corresponding means can be considered statistically equivalent for all variables but the total shots; (c) no statistically significant differences emerged between home and away teams for any of the referee bias variables.

Discussion

These findings demonstrate that the absence of spectators significantly reduced the home advantage compared to previous seasons with spectators. A slight home advantage persisted in the 2020-21 season, probably due to other factors, namely, learning and travel, according to the model by Courneya & Carron (1992). Conversely, the referee bias was not observed, suggesting that it mainly derives from the pressure normally exerted by spectators.

Match Running Performance in UEFA Champions League: Is There a Worthwhile Association with Team Achievement?

Although running performance (RP) is considered an important factor of success in soccer, there is a lack of studies to examine this issue in highest-level soccer competition, such as UEFA Champions League (UCL). Therefore, the main objective of this study was to analyse players' RP according to the achievement of their teams in UCL. In addition, position specific RP of the players who competed in the UCL was evaluated. The players' RPs (n = 244) were collected during UCL group stage matches (n = 20) in the 2020/21 season using semiautomatic optical system InStat Fitness. A team's achievement was defined by qualification of the team from the group stage into the knockout stage of the UCL, and by total group points earned at the end of the UCL group stage. Linear mixed models and Pearson's correlation were used to examine differences in players' RP according to the achievement of their teams. Results indicated (i) similar values of RP irrespective of whether the teams qualified from the group stage into the knockout stage of the UCL, and (ii) trivial-to-small correlations between RP and total group points. Such findings show that players' RP was poorly related to the achievement of their teams in the UCL group stage, indicating trivial influence of RP on success in elite-level soccer.