Match injuries in professional soccer: inter-seasonal variation and effects of competition type, match congestion and positional role.

In this prospective observational study, injuries sustained in official match-play in players belonging to a professional soccer club were investigated. Incidence and patterns of injury were compared across four-seasons (2005-2006: S1, 2006-2007: S2, 2007-2008: S3 and 2008-2009: S4) and 3 match formats (domestic League/Cup games and European club competition). In addition, the effects of both fixture congestion and the positional role of players were investigated. Injury incidence (per 1 000 match-hours) did not vary between seasons (range 31.2-59.2 observed in S2 and S4, respectively, p=0.12) or fixture formats (range 32.6-40.8 observed in European and League matches, respectively, p=0.49). In contrast, rates varied in players (n=7) who participated in all four seasons as more injuries were sustained in S1 compared to S2 and S3, respectively (88.4 vs. 49.0 vs. 49.2, both p<0.05). The incidence of muscle strains was higher in S4 versus S3 (24.7 vs. 9.9, p<0.05) as were injuries sustained to the ankle region in S4 versus S2 (15.1 vs. 4.5, p<0.05). The incidence of joint sprains differed between fixture formats with a higher rate observed in League versus both Cup and European competition, respectively (10.1 vs. 3.0 vs. 3.0, both p<0.05). Injury incidence was not associated to the time delay (number of days) separating games (r=0.04, p=0.58). A very short interval (< or = 3 days) between fixtures did not result in a greater injury rate (p=0.40) or number of days lost to injury (p=0.73) compared to a longer interval (> or = 4 days). Finally, the incidence of injury and muscle strains (both p<0.001) varied across positional roles with the highest rates observed in centre-forwards. These findings provide further knowledge on the risk of injury in contemporary professional soccer match-play and may aid in the care and management of playing resources.