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Prevention of acute knee injuries in adolescent female football players: cluster randomised controlled trial

BMJ 2012; 344 doi: (Published 03 May 2012) Cite this as: BMJ 2012;344:e3042
  1. Markus Waldén, senior researcher12,
  2. Isam Atroshi, associate professor23,
  3. Henrik Magnusson, statistician4,
  4. Philippe Wagner, statistician5,
  5. Martin Hägglund, senior researcher4
  1. 1Division of Community Medicine, Department of Medical and Health Sciences, Linköping University, 581 83 Linköping, Sweden
  2. 2Department of Orthopaedics, Hässleholm-Kristianstad-Ystad Hospitals, 281 25 Hässleholm, Sweden
  3. 3Department of Clinical Sciences, Lund University, 221 84 Lund, Sweden
  4. 4Division of Physiotherapy, Department of Medical and Health Sciences, Linköping University
  5. 5National Competence Centre for Musculoskeletal Disorders, Lund University
  1. Correspondence to: M Waldén markus.walden{at}
  • Accepted 23 March 2012


Objective To evaluate the effectiveness of neuromuscular training in reducing the rate of acute knee injury in adolescent female football players.

Design Stratified cluster randomised controlled trial with clubs as the unit of randomisation.

Setting 230 Swedish football clubs (121 in the intervention group, 109 in the control group) were followed for one season (2009, seven months).

Participants 4564 players aged 12-17 years (2479 in the intervention group, 2085 in the control group) completed the study.

Intervention 15 minute neuromuscular warm-up programme (targeting core stability, balance, and proper knee alignment) to be carried out twice a week throughout the season.

Main outcome measures The primary outcome was rate of anterior cruciate ligament injury; secondary outcomes were rates of severe knee injury (>4 weeks’ absence) and any acute knee injury.

Results Seven players (0.28%) in the intervention group, and 14 (0.67%) in the control group had an anterior cruciate ligament injury. By Cox regression analysis according to intention to treat, a 64% reduction in the rate of anterior cruciate ligament injury was seen in the intervention group (rate ratio 0.36, 95% confidence interval 0.15 to 0.85). The absolute rate difference was −0.07 (95% confidence interval −0.13 to 0.001) per 1000 playing hours in favour of the intervention group. No significant rate reductions were seen for secondary outcomes.

Conclusions A neuromuscular warm-up programme significantly reduced the rate of anterior cruciate ligament injury in adolescent female football players. However, the absolute rate difference did not reach statistical significance, possibly owing to the small number of events.

Trial registration Clinical trials NCT00894595.


  • We thank the study assistants from the Swedish Football Association (Per Renström, professor, Annica Näsmark, physiotherapist, and Anneli Gustafsson, football coach) for their general help with the study, and Jonas Ranstam, senior bio-statistician, for statistical advice. We also thank the coaches and all players who participated in the study, as well as the study therapists and study physicians.

  • Contributors: MW, IA, and MH were responsible for the conception and design of the study. MW and MH coordinated the study and managed all aspects, including data collection. HM provided technical support and was responsible for database management. PW did the analyses, which were planned and checked with the other authors. MW, IA, and MH wrote the first draft of the manuscript. All authors had full access to all data and contributed to interpretation of the findings and critical revision of the manuscript. MW and MH are the guarantors.

  • Funding: The study was financially supported by the Swedish Football Association and the Folksam Insurance Company. This research also received grants from the Swedish National Centre for Research in Sports and from the Hässleholm Hospital. None of the sponsors had any role in the design or conduct of the study; the collection, analysis, and interpretation of the data; or the preparation, approval, and submission of the manuscript. No author or related institution has received any financial benefit from research in this study.

  • Competing interests: All authors have completed the Unified Competing Interest form at (available on request from the corresponding author) and declare: MW, HM, and MH had financial support from the Swedish Football Association and the Folksam Insurance Company; MW and MH received research grants from the Swedish National Centre for Research in Sports and IA received a grant from the Hässleholm Hospital for the submitted work; MW and MH have been paid by the Swedish Football Association for constituting the medical staff of the Swedish male under 19 national team; no other relationships or activities that could appear to have influenced the submitted work.

  • Ethical approval: The study was approved by the regional ethical review board in Linköping (M197-08). Players and parents or guardians gave individual written informed consent.

  • Data sharing: No additional data available.

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