Performance of Professional Soccer Players before and after COVID-19 Infection; Observational Study with an Emphasis on Graduated Return to Play

Abstract

The impact of the COVID-19 pandemic in sport has been the subject of numerous studies over the past two years. However, knowledge about the direct impact of COVID-19 infection on the performance of athletes is limited, and the importance of studies on this topic is crucial during the current pandemic era. This study aimed to evaluate the changes in the match running performance (MRP) of professional soccer players that occurred as a result of COVID-19 infection after fulfilling all of the prerequisites for a safe return to play (RTP). The participants were 47 professional soccer players from a team which competed in first Croatian division (21.6 years old on average) during the 2020/21 season. The total sample was divided into two subgroups based on the results of a PCR test for COVID-19, where 31 players tested positive (infected) and 16 tested negative. We observed the PCR test results (positive vs. negative PCR), the number of days needed to return to the team, number of days needed to RTP after quarantine and isolation, and MRP (10 variables measured by a global positioning system). The number of days where the infected players were not included in the team ranged from 7 to 51 (Median: 12). Significant pre- to post-COVID differences in MRP for infected players were only found for high-intensity accelerations and high-intensity decelerations (t-test = 2.11 and 2.13, respectively; p < 0.05, moderate effect size differences), with poorer performance in the post-COVID period. Since a decrease of the MRP as a result of COVID-19 infection was only noted in two variables, we can highlight appropriateness of the applied RTP. However, further adaptations and improvements of the RTP are needed with regard to high-intensity activities.

The effects of acute respiratory illness on exercise and sports performance outcomes in athletes – A systematic review by a subgroup of the IOC consensus group on “Acute respiratory illness in the athlete”

“…There were nine studies reporting acute (short‐term) effects of acute respiratory infection (ARinf) on exercise performance outcomes (Table 2). In these studies, outcome variables were determined immediately after the ARinf (<2 days) (Weidner, Anderson, Kaminsky, Dick, & Schuur, 1997) within 10 days of the ARinf (Fricker et al, 2005), <30 days (Costello et al, 2021; Csulak et al, 2021; Fikenzer et al, 2021; Komici et al, 2021; Savicevic et al, 2021; Wagemans et al, 2021) or >30 days (Anastasio et al, 2021; Crameri et al, 2020; Wagemans et al, 2021) in the studies investigating SARS‐CoV‐2 infection specifically. In one study, it was not reported how long after the ARinf episode the data were collected (Vaudreuil, Kennedy, Lombardo, & Kharrazi, 2021).…”

“…In three of these studies the diagnosis of ARinf was suspected and the pathogen/s not identified, while in the other three studies SARS‐CoV‐2 infection was confirmed. The sports performance outcome variables were training modifications (Csulak et al, 2021; Fricker et al, 2005; He et al, 2013), match performance (Savicevic et al, 2021; Vaudreuil et al, 2021), or a change in standardised points (Csulak et al, 2021; Pyne et al, 2000). The main findings are conflicting.…”

“…There is evidence that ARinf episodes impair training mileage (Fricker et al, 2005) and overall training load (Cunniffe et al, 2011Fricker et al, 2005) over a 4-5 month period, but there is also evidence that training hours/week post-SARS-CoV-2 infection are not affected (Csulak et al, 2021). Similarly, there was a trend for reduced match performance (Savicevic et al, 2021;Vaudreuil et al, 2021) and standardised performance-dependent points in athletes who had been ill compared to those who remained healthy between two major competitions/seasons (Pyne et al, 2000) as well as evidence of similar improvement in standardised performance-dependent points over two seasons between infected and non-infected athletes (Csulak et al, 2021). In summary, It is currently inconclusive whether training, match performance, or standardised performance points over time are affected or not post-ARinf.…”

Periodic health evaluation in athletes competing in Tokyo 2020: from SARS-CoV-2 to Olympic medals

“…Furthermore, comparing the number of medals won between the athletes who tested positive and those who did not, the period of forced detraining due to the restriction imposed by the RTP protocol did not negatively affect the athlete’s performance. A recent study investigating the performance of professional soccer players before and after COVID-19 showed that it took approximately 3 weeks for asymptomatic and 4–6 weeks for symptomatic players to return to the level of performance preceding the infection 25. With a mean detraining period of 30±13 days, athletes with a previous infection who were allowed to resume physical activity and selected for the Olympics did not win fewer medals than COVID-19– subjects.…”

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

“…Speaking more specifically about soccer teams, the publications on COVID and soccer often focus on particular aspects such as the impact of quarantine or COVID on team sports performance [18,19,[46][47][48] or the psychological impact of the pandemic on players and their families [33,49]. There are reports on the change in sporting outcomes caused by pandemic conditions, such as a lower win ratio when playing in stadiums without a crowd [17, [50][51][52][53][54] and FIFA regulations during the pandemic [55][56][57].…”