Ausl Modena, Sports Medicine, Nurse
Background: In 2020 many people, including professional sportsmen, were in quarantine for many months around the world. Professional sport team players change the modality of training. So, it is indispensable to understand the performance modifications after lockdown.
Methods: A search was conducted on the main international databases considering the studies conducted in team sports.
Results: The studies show a higher injuries incidence in basketball, in futsal and in American football after lockdown. However, there are conflicting data about soccer, in which only incidence about muscular injuries is generally higher.
Conclusions: Lockdown generally increases injuries, above all at the resumption of competitions. It is important give players a sufficient time to recover the athletic condition.
Background: Nel 2020 molte persone, inclusi gli atleti professionisti, sono dovuti stare in quarantena per molti mesi, in varie parti del mondo. Gli atleti professionistici di sport di squadra hanno dovuto cambiare la modalità di allenamento. Perciò, è indispensabile capire i cambiamenti negli indici di infortunio dopo il lockdown.
Metodi: Una ricerca è stata condotta sui principali database condotti nei prinicipali campionati di sport di squadra.
Risultati: Gli studi considerati mostrano un’incidenza maggiore dopo il lockdown nella pallacanestro, nel futsal e nel football americano. Tuttavia, emergono dati contrastanti nel calcio, dove solo gli infortuni muscolari sono generalmente maggiori.
Conclusioni: Il lockdown generalmente ha aumentato gli infortuni, pressochè in tutte le competizioni. È importante dare ai giocatori un sufficiente tempo per recuperare la condizione atletica.
Parole Chiave: Sport di Squadra, Covid-19, Coronavirus, Infortuni, Prestazione
In December 2019, a novel coronavirus, termed “SARS-CoV-2”, announced by the World Health Organization (WHO) as being responsible for the outbreak of COVID-19, was reported . The first case of an unidentified form of viral pneumonia was reported in Wuhan city, Hubei province, China, in December 2019 . As of 24 January 2021, the SARS Covid 2019 syndrome caused 98280844 infections and 2112750 confirmed deaths. The pandemic has led to containment measures and has inevitably had a significant impact on the Western lifestyle, overwhelming and changing, albeit only temporarily, lifestyles, work, leisure and the habits of the world we live in. The lockdown due to the COVID emergency was a critical moment with a strong impact, representing a real traumatic event for mental health of all people . The Covid-19 situation gives also many economic problems for football clubs and other sport: the lack of public in games, caused by the prolonged closure of major Leagues in many sports around the World, damaged seriously team’s finances . Furthermore, the majority of people reduced their physical activity during lockdown, caused by the closure of many sport centers; also elite sportsmen reduced their training [5–7]. The performance changes considerably in team sports: the advantage of home gaming changed, and the performances in the game regarding athletic and technical parameters have collapsed [8–11]. Also, heart and psychological parameters have gotten worse after the lockdown period [12,13]. It is important to understand the similarity between lockdown and detraining: the reduction of ball training changed athletic conditioning of team sports players . It is interesting to evaluate also if the lack of “special conditioning”  increases the injuries in the team sports like soccer. It is hypothesised that the sport detraining could increase injury incidence in sports, especially in high intensity sports. So, the aim of this study is to understand the modifications in the injury rates in soccer, volleyball, basketball, futsal and American football after the lockdown period, analyze the causes, verify if the detraining reduce incidence injuries in team sports and try to find possible solutions in such a way as to be ready for future detraining periods.
The research “soccer covid” gives 146 results on PubMed, 221 on Web of Science, 1758 on SCOPUS at 05 August 2022. The research “football covid” gives 247 results on PubMed, 377 on Web of Science, 2329 on SCOPUS at the same date. The research “futsal covid” gives 4 results on PubMed, 8 on Web of Science, 95 on SCOPUS at the same date. The research “basketball covid” gives 62 results on PubMed, 90 on Web of Science, 818 on SCOPUS at the same date. After removing duplicated results and after reading title, 185 results are considered. After reading abstracts, 34 results are considered. 10 results study the injuries in other sports, 1 study has incomplete data about number of injuries in the population of study and 8 are irrelevant studies. At the end, 15 studies are considered for the review.
The Tables 1, 2, 3 show the authors, the methods, the participant and the results.
During the summer of 2020, the NFL suspended the 2020 preseason on July 21, 2020, making training challenging due to distancing guidelines, limited training camp roster sizes down to 80 players from the typical 90, and less formalized training. The first game played at September 10, 2020. The selected studies are these: Allahabadi  et al collect data about anterior cruciate ligament (ACL) tears in the National Football League (NFL) between the seasons 2013–2020. Bailey et al  conduce two selected studies: one study refers to the NFL’s public injury database about the injury lists throughout the 2017–2020 seasons; the other study  analyses a period of 4 NFL seasons (2016/17 to 2020/21). Omari et al  report the results of publish data about NFL injuries. At the end, Patetta et al  report NFL players’ ACL tears during preseason games and first eight regular season games played of the NFL season for the years 2015–2020 using reports from official NFL team websites (only injuries occurring during regular and preseason games), comparing four phases.
The COVID-19 lockdown occurred since March 11th, 2020 until the Bubble, July 22nd, 2020 (first exhibition scrimmages); the Bubble is the site in which NBA players are situated for ending the Season 2019/20. Cahill et al  conduce a retrospective observational comparative study from the 2017/18 to 2020/21 season about the injury report during the preseason, the first 4 weeks of the regular season and playoffs from the 2017/18 through 2020/21 NBA seasons. Torres-Ronda et al  also conduce a retrospective study analysing the same Seasons.
The only study about Futsal is done by Spyrou et al , that study thirteen elite male futsal players, competing in LNFS and Finalists of the UEFA Futsal Champions League, evaluating only non-contact lower-body injuries. The pre-lockdown injury profile was compiled from January 27th, 2020 to March 13th, 2020 (53.3 +/– 5.4 h of training and 6 matches), and the post-lockdown injuries were collected from May 12th, 2020 to June 24th, 2020 (52.9 +/– 2.8 h of training and 5 matches).
The Serie A was suspended since the 26th matchday, at March 11, 2020, until June 22, 2020, when FIGC (Italian Football Federation, “Federazione Italiana Giuoco Calcio”) officially announced the restart of Serie A. On May 11, 2020 the teams could restart their trainings, initially individual training . Marotta  et al investigated about muscle injuries, pre and post lockdown in the Italian Serie A in the the publicly available media-based platform Transfermarkt, http://www.transfermarkt.com, and divided injuries in severe (> 28 days), moderate (8–28 days) and minor (4–7 days) injuries; also Mazza et al  conduced a retrospective study about injuries (data always from Transfermarkt) in the Serie A league (training and match injuries), divided in 3 time phases of equal length. The English Premier League was suspended in March 9 and restarted on June 17. Mannino et al  investigated about muscular and ligamentous injuries and skeletal injuries in football players in the Premier League across three seasons: 2018/19, 2019/20, and 2020/21. Data are taken from online database.
In Spain, the Government prohibited all individuals from practicing any form of exercise outside of their own residence from 14 March, 2020. LaLiga resumed competition on 8 June of 2020 . Moreno-Pérez et al  compared to the injury rate in the Spanish soccer league (LaLiga) between the rate of the first twenty seven matches and the last eleven matches: In the period before the suspension of the competition due to the COVID-19 pandemic (the first 27 matchdays): the Matchday 28 (first match after suspension) was the fixture with the highest number of injuries.
Bundesliga (German First League) suspended the matches from March 13, 2020 until May 16, 2020, the date of the first match (Matchday 26, the first top Europe League to resume play following the Covid-19 lockdown). Krutsch et al  compared the season 2019/20 with the previous season, also dividing the season 2019/20 in three period and comparing these with the last nine games of the season 2018/19. Seshadri et al  studied eighty two games played following the league suspension in Bundesliga. Thron et al  observed the official match data from the 2019/2020 German Bundesliga, evaluating game performance and injuries in all 306 matches (225 before Covid-19, 81 after).
Orhant et al  investigated time-loss injury occurrence and patterns between the first season (2020/21) completed during the Covid-19 pandemic (longer pre-season following cancellation of the 2019/20 season, a season of shorter duration, because it did not restarted after Covid-19 lockdown, so it finished at March 13, 2020, after 28 matchdays and one game not recovered), and a regular season (2018/19) in French Ligue 1 and 2 professional soccer clubs by a national injury database by each club’s physician. Waldén et al  analyzed the data with a retrospective study about male professional players from 19 premier division teams in 12 countries that participated in the ECIS (UEFA Elite Club Injury Study) during both the 2019/20 and the 2020/21 seasons (considering only 2020).
Nine studies try to study the injuries in soccer, five in football (specifically in NFL), two in basketball (specifically in the NBA), and one in Futsal. No relevant studies found about injuries in volleyball. Thirteen studies give a precise value about injury rates (total or part of the season), seven studies try to understand the difference about specific injuries in a specific sport, and only one study gives the number of injuries divided into seasons without specifying injury incidence. In major sport leagues, there was only a small period of return to normal training before return to play matches, while the first part of the lockdown period consists in individual training [33–38]. Studies about the NFL and NBA investigate several factors: only one study about NFL gives the incidence injuries for the whole season, while other studies investigate about the major type of injury area and the period with the major incidence. The injury incidence in NFL generally increases in post Covid-19 season (above all in the start of the season), with a change in the period of major II (August in post Covid-19, October in normal season) and an increase of muscle injuries [15,17]; the defensive players had a statistically significant increase in injury incidence as compared to other positions, but the increase of the injury incidence is in almost all positions . The unique study that analyses the whole season 2020 gives an injury incidence of 9.47 of 1000 AE . Knee and upper legs have the major II [17,18].
In the NBA the major injury incidence happens during the playoffs in the Bubble (II 2017–20 average 6.4, II post-covid 7) and in the first pre-season post Covid-19, where the injury incidence is lower before the lockdown (II 2017-20 average 1.9, II post-covid 3.4): the major injury rates of muscle and tendon/ligament injuries are during the Bubble period (from July 7–21 to the end of the season) and during the Season 2020/21 . During the first month of regular season the II is lower in the season 2020/21 (II 15.2) as compared to the average 2017–20 (II 12.6) .
In soccer, the results give conflicting data: muscular injuries are generally higher after lockdown, only the study of Marotta  gives a lower result; four studies give an injury incidence lower before the lockdown (for the all types of injuries), four studies give an injury incidence lower after the lockdown. Movement players have a major incidence of injuries after lockdown . The period of restart after lockdown had the major injury incidence . In Futsal it is difficult to understand the influence of lockdown in injury incidence: there is one study that analyzes the situation, with a small number of players.
The period after lockdown gives changes in performance, with a lower high intensity in game running [30, 39–42] and lower physical tests comparing the period before the lockdown [33–38]: the change of training and the lack of ball training with only individual training can reduce the performance and increase the risk of injuries. It is also important to consider that the athletic training increased noticeably during the lockdown period [33–38].
The only athletic individual training seems to do not balance the lack of “special training” (intended as a specific training in which strength and conditioning are used with the ball, the “situational training”), and the only individual training cannot prevent the injuries when strength and conditioning are used at maximal level. It can be a possible link between the lack of game situations and the injury incidence.
After Covid-19 lockdown, an increase of injury incidence is also found in a sport like baseball . A solution for similar future situations can be the use of high intensity interval training and a major number of friendly matches for arriving to the start of the season in a good condition, and a major period of restart (the period of restart must be similar to the period of stop). The periods of team training after lockdown were low, based to local laws, and the consequences have been major injury incidences in many sports.
It is also interesting that only the soccer studies used web “non official” database: the studies about the NBA and the NFL used official websites or reports, and Spyrou  conduced his study on a futsal team, comparing directly injury incidence before and after lockdown.
So, it is indispensable to make the training similar to matches, increasing the game situations. This concept is the same of the detraining after the end of the season, with the same risks of injuries in the first games after the restart, but this time is usually lower as compared to the lockdown period.
The higher muscular II could penalize sport with high intensity like basketball and American football, mostly at the beginning of the resumption of the season, but a long period of preparation seems to reduce the risk of injuries; however, further studies are necessary to understand the impact of this type of detraining in soccer.
Limits: This study presents certain limitations. Some studies analyze injuries in databases like statistic websites; the studies about soccer have notable biases. In the Futsal there is only one study, with few analyzed players.
Conflicts of Interest: The author declares that he has no conflicts of interest associated with this study.
Funding: This research did not receive any form of funding.
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