Model for epidemiological studies on professional soccer player Arliani GG et al. Table 3 - Characteristics of the studies selected for final inclusion. Hagglund et al; 2006 Azubuike & Okojie; 2009 Walde´ n et al; 2005 Paus et al; 2003 Paus et al; 2003 Cohen et al; 1997 Kucera et al; 2005 Selistre et al; 2009 Palacio et al; 2009 Yoon et al; 2004 Martinez & Villani 2003 Ladeira 1999 - Non available. Injury definition Time loss Time loss Time loss Injury during game or practice which withdraw the player Injury during game or practice which withdraw the player Event which lead to loss $1 game Withdrawal $10 days Absence in practice or game Injury confirmed by doctor and absence $2 days Injury which prevent the return at the same or following days Reinjury Similar injury after return Similar injury until 2 months Similar injury less than 8 weeks Study Manual One major concern is how to collect reliable data. One should prepare a study manual to instruct club leaders on proper data collection and recording techniques. This manual should be distributed to participating clubs before the start of the study to prevent any inappropriate collection of data and standardize the definitions used in the study. This manual should include fictitious cases and examples to guide the club leaders.7 Contact Person Professionals should be selected for collecting and recording data before the study begins. The selection of these individuals is extremely important for accuracy, as any changes in the collection method may alter the outcome and comparisons between studies. The person selected must be present at all trainings and games and is often a member of the team’s medical staff. All athletes from the first team should be included in the study. Even athletes with a history of previous injuries should be included because excluding these individuals Table 4 - Inclusion and exclusion criteria. Hagglund et al; 2006 Azubuike & Okojie; 2009 Walde´ n et al; 2005 Paus et al; 2003 Paus et al; 2003 Cohen et al; 1997 Kucera et al; 2005 Selistre et al; 2009 Palacio et al; 2009 Yoon et al; 2004 Martinez & Villani 2003 Ladeira 1999 - Non available. CLINICS 2011;66(10):1707-1712 Rehabilitation complete return (practice and games) complete return (practice and games) complete return (practice and games) Injury severity (days) Mild (1-3)/Minor (4-7)/Moderate (8-28)/Major (.28) Mild (1-3)/Minor (4-7)/Moderate (8-28)/Major (.28) Mild (1-3)/Minor (4-7)/Moderate (8-28)/Major (.28) Mild (1-7)/Moderate (8-21)/Severe (.21) Mild (1-7)/Moderate (8-21)/Severe (.21)/Most severe (.56) Mild (0-7)/Moderate (8-30)/Severe (.30) 1 (0)/2 (1-3)/3 (4-7)/4 (7-30)/5 (.30) Mild (1-7)/Moderate (8-28)/Severe (.28) could lead to bias in the study. An athlete injured at the beginning of the study should not be excluded from the study, but their injury should not be recorded; instead, the athletes’ exposure time will only begin when he or she is fully recovered from injury. Injuries that occur outside the training sessions and games must be separately recorded. For instance, injuries occurring during breaks or while practicing other sports should not be grouped with injuries that occur during training sessions and games. This is critical as the purpose of this study is to assess the risk of soccer-related injuries. Injuries occurring during training and games involving the national team should be registered.22 Injuries occurring during training games against the reserve team or other teams should be considered because the game in question is not part of the rehabilitation of an athlete with a previous injury.7 To allow comparisons between different studies, it is extremely important to define injuries in a uniform man- ner. Various definitions of injury have been used in pre- vious studies. Most of these studies use the definition of withdrawal time (‘‘time loss’’). This definition emphasizes Inclusion/Exclusion criteria All players of the professional team All players registred in the team All players of the professional team All players of the professional team All players of the professional team Amateur players between 16-20 years Injuried players withdrawn $10 dias All players at 2000 Asia Cup and 2000 under 19 asiatic juvenile tournament Under 15/17/20 Argentina national players da Selec¸a˜ o Argentina between 1994 and 2002 Canadian amateur players/Excluded if withdrawn from pratice or game .8 weeks or previous injury 1710