Background The influence of injuries on team performance in football has only been scarcely investigated. Aim To study the association between injury rates and team performance in the domestic league play, and in European cups, in male professional football. Methods 24 football teams from nine European countries were followed prospectively for 11 seasons (2001)(2002)(2003)(2004)(2005)(2006)(2007)(2008)(2009)(2010)(2011)(2012), including 155 team-seasons. Individual training and match exposure and time-loss injuries were registered. To analyse the effect of injury rates on performance, a Generalised Estimating Equation was used to fit a linear regression on team-level data. Each team's season injury rate and performance were evaluated using its own preceding season data for comparison in the analyses.

Background Limited information is available on the variation in injury rates over multiple seasons of professional football. Aim To analyse time-trends in injury characteristics of male professional football players over 11 consecutive seasons. Methods A total of 1743 players comprising 27 teams from 10 countries were followed prospectively between 2001 and 2012. Team medical staff recorded individual player exposure and time loss injuries. Results A total of 8029 time loss injuries were recorded. The match unavailability due to injury was 14% and constant over the study period. On average, a player sustained two injuries per season, resulting in approximately 50 injuries per team and season. The ligament injury rate decreased during the study period (R 2 =0.608, b=−0.040, 95% CI −0.065 to −0.016, p=0.005), whereas the rate of muscle injury (R 2 =0.228, b=−0.013, 95% CI −0.032 to 0.005, p=0.138) and severe injury (R 2 =0.141, b=0.015, 95% CI −0.013 to 0.043, p=0.255) did not change over the study period. In addition, no changes in injury rates over the 11-year period were found for either training (R 2 =0.000, b=0.000, 95% CI −0.035 to 0.034, p=0.988) or match play (R 2 =0.282, b=−0.015, 95% CI −0.032 to 0.003, p=0.093). Conclusions The injury rate has decreased for ligament injuries over the last 11 years, but overall training, match injury rates and the rates of muscle injury and severe injury remain high.

The objective of this study was to investigate regional differences in injury incidence in men's professional football in Europe. A nine-season prospective cohort study was carried out between 2001/02 and 2009/10 involving 1357 players in 25 teams from nine countries. Teams were categorized into different regions according to the Köppen-Geiger Climate Classification System.Teams from the northern parts of Europe (n=20) had higher incidences of injury overall (rate ratio 1.12, 95% CI 1.06 to 1.20), training injury (rate ratio 1.16, 95% CI 1.05 to 1.27), and severe injury (rate ratio 1.29, 95% CI 1.10 to 1.52), all statistically significant, compared to teams from more southern parts (n=5). In contrast, the anterior cruciate ligament injury incidence was lower in the northern European teams with a statistically significant difference (rate ratio 0.43, 95% CI 0.25 to 0.77), especially for non-contact anterior cruciate ligament injury (rate ratio 0.19, 95% CI 0.09 to 0.39). In conclusion, this study suggests that there are regional differences in injury incidence of European professional football. However, further studies are needed to identify the underlying causes.

II.

Background: Previously, no difference in acute injury rate has been found when playing