Physical match performance and injuries in professional soccer before and after the COVID-19 break

Epidemiology of Injury and Illness in North American Professional Men's Soccer: Comparing COVID-19 Lockdown With Previous Seasons

BACKGROUND

After COVID-19 lockdown, studies across Europe and Asia examined its effect on professional soccer injury rates and severity; however, COVID-19 lockdown influence on injuries in United States men's professional soccer has not been evaluated.

HYPOTHESIS

Injury and illness rates during the 2020 season were higher than the previous 2 seasons.

STUDY DESIGN

Retrospective observational cohort study.

LEVEL OF EVIDENCE

Level 3.

METHODS

Medical staff from participating Major League Soccer (MLS) clubs entered injuries and athletic exposures during the study period into a league-wide electronic medical record system. Injury rate and severity were analyzed to examine differentials between the 2020 COVID season and historical controls.

RESULTS

The injury incidence rate per 1000 hours in 2020 was 10.8, ie, higher than 2018 (5.4) and 2019 (5.0) (P < 0.05). Training injury incidence rate increased in 2020 (8.9) compared with 2018 (2.5) and 2019 (2.6) (P < 0.05), whereas match injury incidence decreased in 2020 (18.3) compared with 2018 (24.0) and 2019 (22.7) (P < 0.05). Incidence rates of lower extremity muscle injuries (6.04), anterior cruciate ligament (ACL) injuries (0.17), and concussions (0.49) were also higher in 2020 compared with 2018 (2.5, 0.07, 0.27) and 2019 (2.36, 0.05, 0.22) (P < 0.05). More injured players in 2020 missed >90 days (17.7%) than in 2018 (10.2%) and 2019 (10.1%) (P < 0.05). Incidence of all non-COVID-19 illness was higher in 2020 (3.93) than 2018 (1.53) and 2019 (1.32) (P < 0.05).

CONCLUSIONS

During 2020, there were significant increases in incidence rates of overall injuries, training injuries, lower extremity muscular injuries, ACL injuries, concussions, and non-COVID illness, along with a higher percentage of players missing >90 days compared with the 2 previous seasons.

CLINICAL RELEVANCE

These results may help clarify the effects of future MLS inseason work stoppages and periods of restricted training.

Effects of the New COVID-19-Induced Rule on Substitutions and Performance in Italian Elite Soccer

COVID-19 has resulted in widespread changes, including within the realm of sports. Professional soccer has adapted by allowing more substitutions, leading to tactical adjustments and potential physical benefits. Accordingly, this study analyzed the impact of the new rule in Italian top-level soccer, focusing on substitution patterns and performance differences between the pre-COVID (2017-2018, 2018-2019 seasons) and post COVID (2020-2021, 2021-2022 seasons) eras. As such, publicly available data from 1520 matches (760 matches per era) were recorded. The sample included matches played from 40 Italian top division teams in both the pre- and post-COVID eras. Analyses confirmed substitutions follow a consistent temporal pattern throughout the match in both eras, highlighting a slight difference in second-half management, and showed the new rule is still not used to its full potential, thus raising concerns about teams' financial strength, as not all managers possess "deep benches" (i.e., a large number of top-level players available to play). Further analyses revealed a statistically significant increment (p = 0.002) in the quantity of collectively produced sprints in the post-COVID era compared to the pre-COVID one. The results from this study emphasize the need to carefully address sprint preparation and repeated sprint abilities, also considering factors such as the number of substitutes and their skill level.

Soccer's AI transformation: deep learning's analysis of soccer's pandemic research evolution

Introduction

This paper aims to identify and compare changes in trends and research interests in soccer articles from before and during the COVID-19 pandemic.

Methods

We compared research interests and trends in soccer-related journal articles published before COVID-19 (2018-2020) and during the COVID-19 pandemic (2021-2022) using Bidirectional Encoder Representations from Transformers (BERT) topic modeling.

Results

In both periods, we categorized the social sciences into psychology, sociology, business, and technology, with some interdisciplinary research topics identified, and we identified changes during the COVID-19 pandemic period, including a new approach to home advantage. Furthermore, Sports science and sports medicine had a vast array of subject areas and topics, but some similar themes emerged in both periods and found changes before and during COVID-19. These changes can be broadly categorized into (a) Social Sciences and Technology; (b) Performance training approaches; (c) injury part of body. With training topics being more prominent than match performance during the pandemic; and changes within injuries, with the lower limbs becoming more prominent than the head during the pandemic.

Conclusion

Now that the pandemic has ended, soccer environments and routines have returned to pre-pandemic levels, but the environment that have changed during the pandemic provide an opportunity for researchers and practitioners in the field of soccer to detect post-pandemic changes and identify trends and future directions for research.

Effects of substitute allowance on match activity characteristics in Japanese professional football across 2019, 2020, and 2021 seasons

This study aimed to examine the effects of substitute player allowance per match on running performance in Japanese professional football over three consecutive seasons with different numbers of maximum substitutes. Match running performance was obtained from all outfield players in the official matches of the 1st Division of the Japan Professional Football League over three seasons (2019/2020/2021; 22291 player files) by a 4th generation TRACAB® system which provided the total distance covered (TD) and the number of sprinting runs (SP; ≥24.0 km/h for≥1.0 s). The players were divided according to play time: full match (STA), replaced during match (REP), and substitutes during match (SUB). The number of SUBs increased significantly from 2019 to 2021 (p < 0.05). SUB had a significantly higher average speed than STA and REP. The analysis of covariance with the number of recovery days, ambient temperature, and relative humidity as covariates revealed that the TD and SP significantly differed based on the number of SUBs (p < 0.05). Stepwise regression analysis showed that the number of SUBs significantly contributed to the TD and SP. These results suggest that the new law, which increased the maximum SUB allowance from three to five, improved the match running performance in Japanese professional football.

Wearable technology in the sports medicine clinic to guide the return-to-play and performance protocols of athletes following a COVID-19 diagnosis

The coronavirus disease 2019 (COVID-19) pandemic has enabled the adoption of digital health platforms for self-monitoring and diagnosis. Notably, the pandemic has had profound effects on athletes and their ability to train and compete. Sporting organizations worldwide have reported a significant increase in injuries manifesting from changes in training regimens and match schedules resulting from extended quarantines. While current literature focuses on the use of wearable technology to monitor athlete workloads to guide training, there is a lack of literature suggesting how such technology can mediate the return to sport processes of athletes infected with COVID-19. This paper bridges this gap by providing recommendations to guide team physicians and athletic trainers on the utility of wearable technology for improving the well-being of athletes who may be asymptomatic, symptomatic, or tested negative but have had to quarantine due to a close exposure. We start by describing the physiologic changes that occur in athletes infected with COVID-19 with extended deconditioning from a musculoskeletal, psychological, cardiopulmonary, and thermoregulatory standpoint and review the evidence on how these athletes may safely return to play. We highlight opportunities for wearable technology to aid in the return-to-play process by offering a list of key parameters pertinent to the athlete affected by COVID-19. This paper provides the athletic community with a greater understanding of how wearable technology can be implemented in the rehabilitation process of these athletes and spurs opportunities for further innovations in wearables, digital health, and sports medicine to reduce injury burden in athletes of all ages.

Differences in Physical Match Performance and Injury Occurrence Before and After the COVID-19 Break in Professional European Soccer Leagues: A Systematic Review

Background

Due to the COVID-19 pandemic, matches and soccer-specific training were suspended for several weeks, matches after resumption were congested, and substitutions per team and game increased from three to five.

Objective

The aim of this review was to examine possible differences in physical match performance and injuries between before and after the COVID-19 induced break of matches and training in professional male European soccer leagues during the 2019/2020 season.

Methods

A systematic search identified all scientifically peer-reviewed publications involving elite male soccer players competing in the European leagues which reported physical match performance variables such as total running distance and running distance at different speed zones and/or injury parameters pre- and post-COVID-19 induced break.

Results

In total, 11 articles were included, which were coming from German Bundesliga, Polish Ekstraklasa, Croatian HNL, Spanish La Liga, and Italian Serie A. In all studies investigating the German Bundesliga, most parameters of physical match performance remained unaffected (0.08 ≤ p ≤ 0.82; − 0.15 ≤ ES 0.15), while studies investigating the Polish Ekstraklasa (p ≤ 0.03; − 0.27 ≤ ES − 0.18), Croatian HNL (p ≤ 0.04; − 1.42 ≤ ES ≤ 1.44), Spanish La Liga (p ≤ 0.017; − 0.32 ≤ ES ≤ 5.5), and Italian Serie A (p ≤ 0.014; − 1.01 ≤ ES 0.24) showed a decrease in most parameters of physical match performance after the COVID-19 break. Injury rates were only investigated by studies targeting the German Bundesliga and Italian Serie A. In the majority of studies (3 out of 4 studies), there occurred no difference in injuries between pre- and post-COVID-19 break (p > 0.05; ES = N/A).

Conclusion

Results indicate that Bundesliga teams maintained physical match performance during the 9-weeks break in matches and 3-weeks break in group training, whereas a longer match and group training interruption up to 15 weeks and 8 weeks, respectively, in the other leagues appeared to lead to a decreased physical match performance. Regarding injuries, we speculate that the increase in substitutions from 3 to 5 substitutions per game might prevent an increase in injury occurrence during matches. The underlying studies’ results provide hints for possible upcoming unexpected interruptions with respect to optimal physical preparations for the resumption of matches and a congested schedule to maintain physical match performance, or for possible rule changes such as 5 instead of 3 substitutions to avoid physical overload during congested match schedules.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40798-022-00505-z.

Does Technical Match Performance in Professional Soccer Depend on the Positional Role or the Individuality of the Player?

The aim of the study was to examine the impact of the positional role and the individuality on the technical match performance in professional soccer players. From official match data of the Bundesliga season 2018/19, technical performance [short (<10 m)/medium (10–30 m)/long (>30 m) passes, dribblings, ball possessions] of all players who played during the season were analyzed (normative data). Five playing positions (center back, full back, central midfielder, wide midfielder and forward) were distinguished. As the contextual factor tactical formation is known to influence match performance, this parameter was controlled for. Further, those players who played at minimum four games in at least two different playing positions were included in the study sample (n = 13). The technical match performance of the players was analyzed in relation to the normative data regarding the extent to which the players either adapted or maintained their performance when changing the playing position. When switching playing positions, positional role could explain 3–6% of the variance in short passes and ball possessions and 27–44% of the variance in dribblings, medium passes, and long passes. Moreover, we observed large interindividual differences in the extent to which a player changed, adapted, or maintained his performance. In detail, five players clearly adapted their technical performance when changing playing positions, while five players maintained their performance. Coaches can use these findings to better understand the technical match performance of single players and further, to estimate the impact of a change in the positional role on the technical performance of the respective player.

Injury rates and patterns in French male professional soccer clubs: a comparison between a regular season and a season in the Covid-19 pandemic

This study investigated time-loss injury occurrence and patterns between the first season (2020/21, S2) completed during the Covid-19 pandemic (longer pre-season following cancellation of the 2019/20 season but shorter duration) and a regular season (2018/19, S1) in French Ligue 1 and 2 professional soccer clubs. Epidemiological data were prospectively recorded in a national injury database by each club's physician. In all clubs combined, the mean number of injuries per club was 31.5 and 36.6 in S2 and S1, respectively (-13.9%). Overall match injury incidence (per 1000 hours) in all clubs combined was lower in S2 versus S1 (22.23 vs 25.96, p < 0.01). In Ligue 1 clubs alone, match-play incidences for injury overall (24.92 vs 29.42), muscle strains (10.59 vs 13.24) and strains specifically in the hamstring region (4.52 vs 6.22) were lower in S2 versus S1 (all p < 0.05). No differences in the incidence of match injuries affecting the ankle and knee regions were observed. Changes in the 2020/21 season structure and duration owing to the Covid-19 pandemic seem not to have had a negative effect on injury occurrence and patterns in French professional soccer clubs.