Context: The winter break in the top 2 German professional soccer leagues was shortened from 6.5 to 3.5 weeks in the 2009-2010 season.
Objective: To investigate whether this change affected injury characteristics by comparing the second half of the 2008-2009 (long winter break) with the equivalent period in the 2009-2010 season (short winter break).
Design: Prospective cohort study.
Setting: German male professional soccer leagues.
Patients or other participants: Seven professional German male soccer teams (184 players in the 2008-2009 season, 188 players in the 2009-2010 season).
Main outcome measure(s): Injury incidences and injury characteristics (cause of injury, location, severity, type, diagnosis), including their monthly distribution, were recorded.
Results: A total of 300 time-loss injuries (2008-2009 n = 151, 2009-2010 n = 149) occurred. The overall injury incidence per 1000 soccer hours was 5.90 (95% confidence interval = 5.03, 6.82) in 2008-2009 and 6.55 (5.58, 7.69) in 2009-2010. Match injuries per 1000 hours were 31.5 (25.0, 38.0) in the first season and 26.5 (20.2, 32.7) in the second season; the corresponding training values were 2.67 (2.08-3.44) and 3.98 (3.19-4.95), respectively. The training injury incidence (incidence rate ratio = 1.49 [95% confidence interval = 1.07, 2.08], P = .02) and the risk of sustaining a knee injury (incidence rate ratio = 1.66 [1.00, 2.76], P = .049) were higher in 2009-2010 after the short winter break; the incidence of moderate and severe injuries (time loss >7 days) trended higher (incidence rate ratio = 1.34 [0.96, 1.86], P = .09).
Conclusions: Shortening the winter break from 6.5 to 3.5 weeks did not change the overall injury incidence; however, a higher number of training, knee, and possibly more severe injuries (time loss >7 days) occurred.
Keywords: epidemiology; football; inadequate recovery; injury incidence; injury surveillance.