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The Adductor Strengthening Programme prevents groin problems among male football players: a cluster-randomised controlled trial
  1. Joar Harøy1,
  2. Benjamin Clarsen1,
  3. Espen Guldahl Wiger1,
  4. Mari Glomnes Øyen1,
  5. Andreas Serner2,3,
  6. Kristian Thorborg2,
  7. Per Hölmich2,
  8. Thor Einar Andersen1,
  9. Roald Bahr1
  1. 1 Department of Sports Medicine, Norwegian School of Sport Sciences, Oslo Sports Trauma Research Center, Oslo, Norway
  2. 2 Department of Orthopedic Surgery, Sports Orthopedic Research Center, Copenhagen, Copenhagen University Hospital, Amager-Hvidovre, Denmark
  3. 3 Aspetar Orthopaedic and Sports Medicine Hospital, Doha, Qatar
  1. Correspondence to Joar Harøy, Department of Sports Medicine, Norwegian School of Sport Sciences, Oslo Sports Trauma Research Center, Oslo 0806, Norway; joar.haroy{at}


Background Groin injuries represent a considerable problem in male football. Previous groin-specific prevention programmes have not shown a significant reduction in groin injury rates. An exercise programme using the Copenhagen Adduction exercise increases hip adduction strength, a key risk factor for groin injuries. However, its preventive effect is yet to be tested.

Aim To evaluate the effect of a single-exercise approach, based on the Copenhagen Adduction exercise, on the prevalence of groin problems in male football players.

Methods 35 semiprofessional Norwegian football teams were cluster-randomised into an intervention group (18 teams, 339 players) and a control group (17 teams, 313 players). The intervention group performed an Adductor Strengthening Programme using one exercise, with three progression levels, three times per week during the preseason (6–8 weeks), and once per week during the competitive season (28 weeks). The control group were instructed to train as normal. The prevalence of groin problems was measured weekly in both groups during the competitive season using the Oslo Sports Trauma Research Center Overuse Injury Questionnaire.

Results The average prevalence of groin problems during the season was 13.5% (95% CI 12.3% to 14.7%) in the intervention group and 21.3% (95% CI 20.0% to 22.6%) in the control group. The risk of reporting groin problems was 41% lower in the intervention group (OR 0.59, 95% CI 0.40 to 0.86, p=0.008).

Conclusion The simple Adductor Strengthening Programme substantially reduced the self-reported prevalence and risk of groin problems in male football players.

Trial registration number ISRCTN98514933.

  • football
  • groin
  • injury prevention
  • strength

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  • Twitter Follow @jharoey, @benclarsen, @aserner, @kthorborg, @perholmich, @docthorandersen, @roaldbahr, @ostrc1.

  • Contributors With exception of EGW and MGØ, all authors have been involved in the planning of the study. JH, BC, EGW, MGØ, TEA and RB performed the data collection. All authors have been involved in the data analyses, drafting and revision of the manuscript, and have approved the final version.

  • Funding The Oslo Sports Trauma Research Center has been established at the Norwegian School of Sport Sciences through generous grants from the Royal Norwegian Ministry of Culture, the South-Eastern Norway Regional Health Authority, the International Olympic Committee, the Norwegian Olympic Committee & Confederation of Sport, and Norsk Tipping AS.

  • Competing interests None declared.

  • Patient consent Not required.

  • Ethics approval This cluster-randomised controlled trial was registered with the International Standard Randomised Controlled Trial Number registry (ISRCTN98514933). The study was approved by the South-Eastern Norway Regional Committee for Medical Research Ethics (2015/1922/REK) and the Norwegian Data Inspectorate (45388/3/LT/LR).

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Data sharing statement The players were not involved in the design of research question, outcome measures, design or recruitment to the study. The results from the study will be disseminated to all teams that were included in the project. Applications for data sharing can be made.