gms | German Medical Science

Objectives: The SARS-CoV-2 virus pandemics led to a global shut down in indoor, as well as outdoor team sports. Although airborne transmission and distance of infectious particle is already well described in literature, information about safety of outdoor team sports and in particular in football is lacking. This study should provide first time data about contact time of players during matches in German professional football.

Methods: This investigation provides data by measurements of the optic tracking system TRACAB Gen5 by ChyronHego (Sportec Solutions) of matches in the two highest professional football leagues in Germany (Bundesliga and 2nd Bundesliga) in the season 2019-20 and the first half of the season 2020-21. 25 pictures per second (25 Hz) were recorded by 16 to 20 cameras in each stadium and analysed in regard to contact of players in a radius of 2 meters. Hygienic regulations were considered regarding the Robert-Koch-Institute (RKI), which includes distance recommendation of up to 2 meter to next persons and a up to 15 minutes face-to-face contact classification for contact persons of infected persons with Covid-19 to receive a direct quarantine. Non-football-specific contacts like goal celebrations, shake hands after goals or group buildings in long match disruptions after referees' decisions are not allowed during the pandemic and were therefore not registered in this survey.

Results and Conclusion: In total 918 matches of 3 study periods and 173,379 player contactswere analyzed. The average contact time of a player within a 2-meter radius with the sum of all other players on football field was 6.7 minutes. Before lockdown a contact time of 7.4 minutes was registered, while after the lockdown a reduction of mean player contacts to 6.4 minutes was measured. Before lockdown 94.6 % of the players had less than 15 minutes of player contact within a 2-meter radius during a match, while after lockdown the proportion of total contact time under 15 minutes raised to 96.5 %. In the calculation of 1-to-1 player pairs before the lockdown a mean contact time of 24 seconds to another player on field was found. After the lockdown contact of player pairs was reduced to 18 seconds per match. Meanwhile contact of longer than 2 minutes was more frequent seen before lockdown with 4.6 % (n=1,776) compared to the period after lockdown 3.7 % (n=1,742).

This first presentation of player contacts in professional football shows that football is a contact sport with moderate to less frequent contact during matches. Considering less frequent player contacts and the outdoor sport setting with greater distances between players on a large playing field, the possibility for transmission of viral diseases on the field seems to be unlikely. However, overall contact time and contact of specific player pairs was reduced after the SARS-CoV-2 caused lockdown in Germany compared to the period before the pandemic, which seems to be a consequence of the pandemic on players behaviour on field.