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Effectiveness of a judo-specific injury prevention programme: a randomised controlled trial in recreational judo athletes
  1. Amber L von Gerhardt1,2,3,
  2. Guus Reurink2,3,
  3. Gino M M J Kerkhoffs1,2,3,
  4. Evert Verhagen2,4,
  5. Kai Krabben5,
  6. Jeroen Mooren6,
  7. Jessica S I Gal7,
  8. Arnold Brons8,
  9. Ronald Joorse9,
  10. Benny van den Broek5,
  11. Ellen Kemler10,
  12. Johannes L Tol1,2,3
  1. 1 Orthopedic Surgery and Sports Medicine, Amsterdam UMC—Locatie AMC, Amsterdam, The Netherlands
  2. 2 Amsterdam Collaboration on Health & Safety in Sports (ACHSS), IOC Research Center, Amsterdam, The Netherlands
  3. 3 Academic Center for Evidence-Based Sports Medicine (ACES), Amsterdam UMC, Amsterdam, The Netherlands
  4. 4 Department of Public and Occupational Health, EMGO, Amsterdam UMC Locatie VUmc, Amsterdam, The Netherlands
  5. 5 Judo Bond Nederland (JBN), Nieuwegein, The Netherlands
  6. 6 Sports Medicine, CWZ, Nijmegen, Gelderland, The Netherlands
  7. 7 Jessica Gal Sportartsen, Amsterdam, The Netherlands
  8. 8 International Judo Federation (IJF) Medical Committee, Boedapest, Hungary
  9. 9 Amsterdam Football Club (AFC) Ajax, Amsterdam, The Netherlands
  10. 10 Dutch Consumer Safety Institute, Amsterdam, The Netherlands
  1. Correspondence to Amber L von Gerhardt, Orthopedic Surgery and Sports Medicine, Amsterdam UMC - Locatie AMC, Amsterdam, Netherlands; a.vongerhardt{at}


Objectives To evaluate the effectiveness of a trainer-supervised judo-specific injury prevention warm-up programme on overall injury prevalence.

Methods We conducted a two-arm, cluster randomised controlled trial; the Injury Prevention and Performance Optimization Netherlands (IPPON) study. Judo athletes aged≥12 years were randomised by judo school to IPPON intervention or control group who performed their usual warm-up. Primary outcome was overall injury prevalence (%) over the follow-up period (16–26 weeks) measured fortnightly with the Oslo Sports and Trauma Research Centre Questionnaire. A modified intention-to-treat analysis was performed due to COVID-19, with estimates for the primary outcome obtained using generalised linear mixed models. Secondary outcomes included: prevalence of severe injuries, overall incidence, time-loss injuries, exposure, adherence and experiences of trainers and athletes.

Results 269 judo athletes (IPPON: 117, Control: 152) were included. Mean injury prevalence over 16–26 weeks was 23% (95% CI 20% to 26%) in the IPPON and 28% (95% CI 25% to 30%) in the control group. We observed no significant difference of all reported injuries (OR 0.72 in favour of the IPPON group; 95% CI 0.37 to 1.39). Secondary outcomes also demonstrated no significant differences between groups. Specifically, no significant difference of severe injuries was reported (OR 0.80 in favour of the IPPON group; 95% CI 0.36 to 1.78). All trainers and 70% of athletes perceived the IPPON intervention as successful.

Conclusion The IPPON intervention did not significantly reduce the overall and severe injury prevalence. Despite this, we suggest the IPPON intervention be considered as an useful alternative to regular judo warm-up, given the high adherence and the positive clinical experiences of trainers and athletes.

Trial registration number NTR7698.

  • athletes
  • athletic injuries
  • martial arts
  • randomized controlled trial
  • sporting injuries

Data availability statement

All data relevant to the study are included in the article or uploaded as online supplemental information.

This article is made freely available for personal use in accordance with BMJ’s website terms and conditions for the duration of the covid-19 pandemic or until otherwise determined by BMJ. You may use, download and print the article for any lawful, non-commercial purpose (including text and data mining) provided that all copyright notices and trade marks are retained.

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Data availability statement

All data relevant to the study are included in the article or uploaded as online supplemental information.

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  • Twitter @AvonGerhardt, @Evertverhagen, @JeroenMooren

  • Contributors ALvG, GR, EV, GMMJK and JLT were involved in the design of the trial. ALvG and BvdB were involved in the recruitment. ALvG was involved in the data collection, performed the statistical analysis and was responsible for drafting the manuscript. All authors reviewed and agreed on the manuscript. ALvG and JLT are the study guarantors.

  • Funding This study was partly funded by a grant from the Netherlands Organisation for Health Research and Development (ZonMw).

  • Competing interests None declared.

  • Patient and public involvement Patients and/or the public were not involved in the design, or conduct, or reporting, or dissemination plans of this research.

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

  • © Author(s) (or their employer(s)) 2023. No commercial re-use. See rights and permissions. Published by BMJ.

  • Supplemental material This content has been supplied by the author(s). It has not been vetted by BMJ Publishing Group Limited (BMJ) and may not have been peer-reviewed. Any opinions or recommendations discussed are solely those of the author(s) and are not endorsed by BMJ. BMJ disclaims all liability and responsibility arising from any reliance placed on the content. Where the content includes any translated material, BMJ does not warrant the accuracy and reliability of the translations (including but not limited to local regulations, clinical guidelines, terminology, drug names and drug dosages), and is not responsible for any error and/or omissions arising from translation and adaptation or otherwise.