Football (soccer) is the world's most popular sport. According to the Federation Internationale de Football Association (FIFA), there are 265 million male and female registered football players worldwide and of these, 46 million (17%) are from Africa; third largest after Asia (33%) and Europe (23%) (FIFA, 2006). Furthermore, 56.3% and 69.5% of all registered players are youth of 18 years and below globally and in Africa respectively (FIFA, 2006).
Africa is a continent with major developmental challenges like poverty, hunger, infectious and non-infectious diseases. Over the last decade, the use of sport as a tool to achieve development goals has gained immense support worldwide and football is the sport most frequently used. Hence, football may serve as a tool for reducing crime and poverty among young players. Furthermore, participation in football is an effective way for youths to increase their level of physical activity and fitness.
It has being emphasized that prevention of injuries should always be a priority and is even more important when treatment possibilities are restricted, as in many parts of Africa (Constantinou, 2010). Football players in Africa are faced with huge challenges. Funding is generally low and medical support appears poor especially in youth football and at the grass-roots. A recent study revealed an inadequacy in the medical coverage in a cohort of male youth football players in Lagos, Nigeria (Owoeye et al., 2013). The study further exposed that players rarely had qualified medical attendants; as masseurs predominantly attended to players during training and matches (Owoeye et al., 2013). Thus, the importance of injury prevention in youth football players in the region cannot be overemphasized. Implementation of injury prevention programmes in this extremely vulnerable population of disadvantaged youths is highly imperative.
In order to abate the high risk of injuries in football, FIFA's Medical Assessment and Research Centre (FMARC) has developed a neuromuscular injury-prevention programme, referred to as FIFA 11+, to help reduce the incidence of injuries in football (F-MARC, 2013). The FIFA 11+ is a comprehensive warm-up programme developed by F-MARC and experts in the field of football medicine to reduce injuries among male and female football players aged 14 years and above. Sadly, implementation of this programme appears to be limited in the African region. Furthermore, there seems to be a low level of awareness of the FIFA 11+ programmes among players and coaches. Over three-quarters (79.3%) of male youth football players in Lagos, Nigeria were reported not to be aware of FIFA 11+ (Owoeye et al., 2013).
Several studies have been conducted to test the efficacy of injury prevention programmes in football (Aaltonen et al., 2007; Alentorn-Geli et al., 2009; Arnason et al., 2008; Askling et al., 2003; Emery and Meeuwisse, 2010; Grooms et al., 2013; Heidt et al., 2000; Junge and Dvorak, 2004; Peterson et al., 2011; Soligard et al., 2008; Steffen et al., 2013). However, to our knowledge, none of these programmes have been tested in an African population and most studies were conducted on female players. Specific injury prevention programmes such as the FIFA 11+, Prevent Injuries and Enhance Performance (PEP) programme and the Harmoknee Programme have been reviewed to be effective neuromuscular warm-up programmes requiring no additional equipment for preventing lower extremity (LE) injuries in football (Herman et al., 2012). These injury prevention programmes reduced the rate of LE injuries by 32-95% in female football players (Herman et al., 2012).
Other injury prevention programmes focusing on intrinsic risk factors have also been shown to reduce the risk of injuries in heterogeneous populations of football players (Aaltonen et al., 2007; Arnason et al., 2008; Askling et al., 2003; Emery and Meeuwisse, 2010; Junge and Dvorak, 2004; Peterson et al., 2011). In addition, a neuromuscular warm-up programme targeting core stability, balance, and proper knee alignment effectively reduced non-contact anterior cruciate ligament injuries by 64% in Swedish female football players. In another cohort study, the FIFA 11+ reduced the overall risk of LE injury in collegiate male football players in the United States of America by 72% (Groom et al., 2013).
The FIFA 11+ is a comprehensive warm-up programme aimed at improving muscular strength, body kinesthetic awareness, and neuromuscular control during static and dynamic movements. The FIFA 11+ is one of the few structured exercise based injury prevention programmes presently available in football. However, its efficacy is yet to be fully documented in literature as it has only been tested in randomised controlled trials (RCTs) in young female footballers in Norway (FMARC, 2013; Soligard et al., 2008; Steffen et al., 2013). Soligard et al. (2008) reported an overall significant reduction of 32% in injury rate in teams that performed FIFA 11+ while Steffen et al. (2013) reported an overall significant injury reduction of 72% based on secondary data analysis. Randomised controlled trials on the efficacy of the FIFA 11+ injury prevention programme in reducing injury rate among young male football players are presently lacking and its potency in minimising the incidence of injuries in African players is unknown. We therefore conducted a cluster RCT to evaluate the effects of the FIFA 11+ programme on male youth football league players in Lagos, Nigeria.
Study design, participants and randomisation
A cluster randomised controlled trial was conducted. A cluster design was adopted so as to administer the INT programme to teams and not directly to individual players thereby minimising contamination between the INT and CON groups. Data collection procedures and definitions used in the present study were in accordance with international consensus guidelines for injury surveillance in football (Fuller et al., 2006).
The sample frame for this study consisted of 20 teams (416 players) of the Premier League division of the Lagos Junior League (LJL) registered for the 2012/2013 season. Blocked randomisation technique was used to equally allocate the 20 teams into 2 groups and teams were prospectively followed for a period of 6 months (September, 2012 to February, 2013) through the 2013/2013 league season.
The randomisation procedure for this study was based on team clusters with regards to the official list of premier league teams registered for the season. A randomisation block comprising 4 unlabelled teams was chosen based on the intended number of groups (two) (Kang et al., 2008). A total of 6 possible blocks were derived from a probability/balanced combination of teams from a list of 20 teams. Five blocks were randomly chosen and a random sequence was then used to assign prelisted teams into equal numbers per group. Ten teams were randomly allocated to an intervention (INT) group (212 players) and 10 teams to the control (CON) group (204 players) (Figure 1). All the 20 teams completed the study and all players with available data were involved in the final analysis based on the intention to treat principle (Mohar et al., 2010).
The 11+" is a structured, exercise-based warm-up programme aimed at reducing injuries among male and female football players aged 14 years and above (Soligard et al., 2008). This neuromuscular training programme consists of three parts. The initial part is running exercises at slow speed combined with active stretching and controlled contacts with a partner. The running course includes six to ten pairs of cones (depending on the number of players) about...