The incidence of anterior cruciate ligament (ACL) injuries in football is 3-6 times higher in females than in males. A variety of different prevention approaches have been tested, ranging from balance and plyometric training, to flexibility and eccentric hamstrings training. There have been promising results; however, the knowledge about injury prevention programs in female football is still limited, due to study limitations and a lack of studies. Hence, there is a need for prospective, randomized intervention studies, to investigate the efficacy of training programs aimed to reduce injuries in football, especially among young players.
'The 11+', known as 'SPILLEKLAR!' in Norwegian, is a 20-minute warm-up program, developed by an expert group convened by FIFA. By improving strength, awareness and neuromuscular control the program is targeting the most common injury types in football targeting the most common injury types in football, i.e. ankle and knee sprains, and injuries to the groin and hamstring. The program was designed based on previous research and combines key exercises from the 'F-MARC 11'-program and the 'PEP'-program with running exercises.
The main purpose of this project was to examine the effect of the '11+' warm-up program on lower extremity injury rates in female youth football, in a cluster randomized controlled trial.
This prospective cluster randomized controlled intervention study had a continuous injury registration from March to October 2007. Approximately 125 teams which participated in the 'J16'-series (girls aged 14-16 years) in the middle and south of Norway were included, corresponding to around 2 500 players. The teams were randomized to either the intervention group or the control group. An inclusion criterion was that the teams had conduct at least two training sessions per week, in addition to match play, to be allowed enrollment. The teams in the intervention group were introduced to the '11+' program in the pre-season and followed it during the entire season as a part of each training session. The running exercises were also used as warm-up before matches. The teams in the control group warmed up and trained as usual throughout the season.
The coaches and team captains from all the teams in the intervention group were invited to educational courses where the '11+' warm-up program was introduced. These courses were arranged in each region by instructors from the Oslo Sports Trauma Research Center. Through thorough instruction the participants learned to focus on knee control and awareness, landing techniques, cutting and planting - all factors known to be important in preventing lower extremity injuries. To make the instruction of their own players easier, the coaches received an attractive loose-leaf notebook, which included an instructional booklet and weekly registration forms; a pamphlet and a DVD. Additionally, every player received a poster describing the exercises through pictures and text.
Throughout the season the coaches registered injuries and individual player participation for each training session and match on weekly registration forms, as well as to what extent the warm-up program was carried out each session. A call center established at the Oslo Sports Trauma Research Center, staffed by physical therapists and medical students, called every injured player to assess aspects of the injury based on a standardized injury questionnaire. An injury was registered if it caused the player to be unable to fully take part in the next match or training session, as recommended in the FIFA consensus statement.
The main findings from the study were unequivocal; injuries overall were reduced by 32% and serious injuries were reduced by 45%. The risk of overuse injuries was reduced by 53%, while a reduction of lower extremity injuries of 29% did not reach statistical significance. The results also revealed that the players with high compliance with the program experienced an extended risk reduction of 35% compared to the players with intermediate compliance with the program.
This study has demonstrated that injury prevention training should be implemented as a core element of coach education and training programs in female youth football. The warm-up program can easily be adjusted and used by football players of both gender and from every age level.