Systematic development of an injuryprevention programme for judo athletesthe IPPON intervention

Amber L von Gerhardt 123 Ingrid Vriend 34 Evert Verhagen 34

Johannes L Tol 23 Gino M M J Kerkhoffs 123 Guus Reurink23

ABSTRACTObjectives To systematically develop an injury preventionprogramme in judo and test its feasibility Injury Preventionand Performance Optimization Netherlands (IPPON)interventionMethods We used the five-step Knowledge TransferScheme (KTS) guidelines In the first two steps wedescribed the injury problem in judo and showedpossibilities to reduce the injury rates In the third step theKnowledge Transfer Group (KTG) translated this informationinto actions in judo practice Expert meetings and practicalsessions were held In the fourth step we developed theinjury prevention programme and evaluated its feasibility injudo practice in a pilot study As a final step we will evaluatethe injury prevention programme on its effectiveness toreduce injuriesResults In the first two steps information collectedindicated the need for reducing judo injuries due to highincidence rates Injury prevention programmes have shownto be effective in reducing injuries in other sports For judono injury prevention programme has yet beensystematically developed In the third step the KTG reachedconsensus about the content a trainer-based warm-upprogramme with dynamic exercises focusing on theshoulder knee and ankle In the fourth step the interventionwas developed All exercises were approved in the pilotstudy Based on the pilot studyrsquos results the IPPONintervention was extended and has become suitable for thefinal stepConclusion We developed the IPPON intervention usingthe systematic guidance of the KTS This trainer-basedprogramme focuses on the prevention of shoulder knee andankle injuries in judo and consists of 36 exercises classifiedin three categories (1) flexibility and agility (2) balance andcoordination and (3) strength and stability Theeffectiveness and feasibility of the intervention on injuryreduction among judo athletes will be conducted ina randomised controlled trial

INTRODUCTIONJudo is a Japanese combat sport with approxi-mately 20 million active participants in morethan 200 affiliated countries spread over allcontinents1 There are many health benefitsof participating in judo such as the increaseof physical capabilities andmental resilience2

Although the International Judo Federation(IJF) places a large emphasis on athlete safety

the injury rates in both competitive andrecreational judo are high3ndash5 The reportedincidence of injuries is up to 29 in elite judoathletes during competition6 Judo injuriesare highly prevalent in recreational Dutchjudo athletes as well with up to 41 of thejudo athletes being injured within the 3 pre-ceding months7 These injuries can lead tosignificant periods of time loss from sportswith a negative impact on performance8

Long-term effects of joint injuries increasethe risk of osteoarthritis development andjoint instability causing limitations in dailylife sports andor work9 Thus injuries injudo could potentially lead to importantshort-term and long-term problemsSport-specific injury prevention pro-

grammes in several sports have been proveneffective in reducing the rates of sport injuriesin both recreational and elite athletes10ndash12

For individual contact sports as judo the prac-tical use of these theoretical programmes isdifficult due to the following reasons First

To cite von Gerhardt ALVriend I Verhagen E et alSystematic development of aninjury prevention programmefor judo athletes the IPPONintervention BMJ Open Sport ampExercise Medicine 20200e000791 doi101136bmjsem-2020-000791

Supplemental material ispublished online only To viewplease visit the journal online(httpdxdoiorg101136bmjsem-2020-000791)

Received 18 March 2020Revised 25 June 2020

copy Author(s) (or theiremployer(s)) 2020 Re-usepermitted under CC BY-NC Nocommercial re-use See rightsand permissions Publishedby BMJ

For numbered affiliations seeend of article

Correspondence toAmber L von Gerhardtavongerhardtamsterdamumcnl

Summary box

What are the new findings A new feasible judo-specific injury prevention

programme was developed to reduce andorprevent the occurrence of musculoskeletalshoulder knee and ankle injuries in judo using theKnowledge Transfer Scheme

The IPPON intervention consists of 12 exercises(choice from 36 unique exercises) lastingapproximately 10 min and performed two timesper week

Information and instructions about the IPPONintervention are available on photo and descriptioncards instruction book and instruction videos

How might it impact on clinical practice The effectiveness and feasibility of the IPPON

intervention to reduce andor prevent theoccurrence of musculoskeletal injuries in judoneeds to be evaluated in a randomised controlledtrial among judo athletes

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these programmes are often developed for team sports13

Second there is a missing link between theory and judopractice The practical tool to develop an injury preven-tion programme that combines theory and practice is theKnowledge Transfer Scheme (KTS)14

Up to now only two judo-specific injury preventionprogrammes have been described in the literature15 16

Both programmes were not systematically developedusing a practical tool and the feasibility in practice andthe effectiveness of these programmes to prevent injurieshave not been evaluated yet Especially the systematicdevelopment process of an intervention for judo basedon evidence and practical experience is essential for suc-cessful implementationTherefore the aim was to systematically develop an

injury prevention programme for judo athletes to preventmusculoskeletal injuries among judo athletes and assessits feasibility in the judo practice in a pilot study In thispaper we described in detail the development processpreparation and procedures in the run-up to the inter-vention phase We hypothesised that we could developa practically applicable injury prevention programmeusing the KTS

METHODSThe medical ethics committee of the Academic MedicalCenter Amsterdam granted exempt status (qualified asnon-WMO obliged research W19_071) The study wasfunded by The Dutch Organization for Health andResearch and Development (ZonMw) Patients or the

public were not involved in the design conduct report-ing and dissemination plans of our research

Development processSuccessful intervention programmes would require theo-retical research frameworks combined with practicalimplementation17 Several research frameworks havebeen described in the literature18 19 These frameworksfocused on knowledge and evidences derived fromresearch however these remain silent on practical imple-mentation The KTS combines theory and practice byintegrating existing research frameworks into a practicaltool Therefore for the development of the Injury Pre-vention and Performance Optimization Netherlands(IPPON) intervention we used the KTS14

The KTS described a systematic process to developinjury prevention interventions in sports The bottom-up approach of the KTS takes into account the facilitatorsand barriers to the implementation of these interven-tions This bottom-up approach indicates the involve-ment of end-users in the process and has beensuccessfully applied in other sports like hockey andtennis20 21 The KTS consists of five steps (figure 1)

Step 1 Problem statementThe injury problem in judo was described in terms of itsmagnitude severity societal importance and societal bur-den We searched the literature (search termsmdashlsquomartialartsrsquo lsquojudorsquo and lsquoinjuriesrsquo) for information about injuriesamong judo athletes3ndash6 22ndash24

- 2 -Evidence

description

Evidence

- 4 -Product

development

- 5 -Evaluation

- 3 -Knowledge

transfer group

Bottom up

Top down

- 1 -Problem

statement

Pilotstudy

Expert meetings + Tatami

sessions

Practice

Figure 1 Flow chart of the modified Knowledge Transfer Scheme development process

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Step 2 Evidence descriptionWe described available evidence to solve the problem thatwas postulated in the first step The literature wassearched (search termsmdashlsquojudorsquo lsquoinjuriesrsquo and lsquopreven-tionrsquo) for evidence-based injury prevention programmesin judo

Step 3 Knowledge Transfer GroupA Knowledge Transfer Group (KTG) was established totranslate the information from the first two steps intopractical actions The KTG consisted of key practitionerstakeholders and researchers with expertise on the injuryor evidence at hand Threemeetings of 2 hours each wereorganised with the KTG In the first KTG meeting thegoals of the intervention were formulated and potentialbarriers and facilitators for the adoption and implemen-tation of the intervention were discussed In addition tothe KTS the coordinating researcher (AvG) met with thejudo experts of the KTG individually The available injuryprevention programmes for judo were independently dis-cussed to collect information about the practical use andfeasibility of these exercises in daily judo practice15 16

Focus domains for the intervention were determinedand ideas for new exercises were assembled In theabsence of evidence-based judo-specific injury preventionexercises extra sessions were held in judogi (traditionaluniform used for judo practice) on the tatami (judotraining ground) to modify existing exercises and addnew exercises Members of the KTG chose their top fourexercises for each category and selected the most chosenexercises for inclusion In the second KTG meeting thecontent of the proposed intervention programme waschosen and the concept intervention was delineated

Step 4 Product developmentWe described the development of the injury preventionprogramme All information assembled in the previoussteps was compiled for the development of the interven-tion including exercises and instruction materials Weconducted a 4-week pilot study to determine whether theconcept exercises were feasible could be completedwithin15 min and whether the instruction materials were usefulTrainers were invited to participate with their athletesInclusion criteria for judo athletes were as follows (1) 12years of age or older (2) train at least two times per weekand (3) capable of speaking and reading the Dutch lan-guage Trainers were instructed by two former elite judoathletes on how to execute the exercises correctly Photoand description cards and video instruction recordings ofthese exercises were available as instruction materials (inDutch) The athletes performed the trainer-supervisedexercises at the start of each trainingFor the pilot study

Trainers were asked to track the performed exerciseseach training on standardised forms (online supplemental material 1)

Structured observations were held by the coordinat-ing researcher in the first and the final training

session using standardised forms with specific pointsof interests (online supplemental material 2) and

At the end of the final training session the coordinat-ing researcher interviewed all trainers (individualinterviews) and all athletes (group interviews) Inter-views were held using standardised forms (online supplemental material 3) Questions to assess the inter-vention referred to (1) instructions the use of materi-als provided (2) practical use the structure andsequence of the exercises (3) usefulness the adoptionand implementation of the intervention in judo prac-tice (4) time duration the length of the exercises andwarm-up as a whole and (5) difficulty the complexitylevel of the exercises (defined as one two or three starlevels)

In the third KTG meeting the results of the pilot studywere discussed and the intervention programme wasmodified where appropriate

Step 5 Evaluation of the interventionAs a final step we will evaluate the effectiveness of theinjury prevention programme on injury reduction

RESULTSThe main findings are summarised in table 1

Step 1 Problem statementInformation collected on the injury problem indicatedthat an intervention to prevent injuries for judo athletes isneeded for recreational and elite athletes5 25ndash29 It shouldfocus on the prevention of musculoskeletal injuries in thefingers shoulder knee and ankle26 27 Trainers and coa-ches were open to implement the intervention as part ofthe standard warm-up prior to the training

Step 2 Evidence descriptionSport-specific injury prevention programmes have shownto be effective in reducing sport injuries10 These warm-up programmes generally focus on exercises that aim toimprove physical skills of the athlete In judo there isa lack of evidence-based prevention programmes thathave been tested for feasibility andor effectiveness Norandomised controlled trials (RCTs) on judo injury pre-vention strategies were identified

Step 3 Knowledge Transfer GroupThe multidisciplinary KTG consisted of 14 members(online supplemental material 4) Members had exper-tise on judo sports medicine sports injuries injury pre-vention andor implementation of injury preventionstrategies The expert group consisted of two formerjudo athletes who participated in the Olympic Gamesand who are currently working as a sport physician Twoformer international judo athletes are current judo trai-ners There was one representative of the Dutch judoassociation Three sport physicians participated of whichone is part of the medical commission of the IJF and wasthe former union doctor of the Dutch judo association

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There was one orthopaedic surgeon specialised andexperienced in judo injuries Two human movementscientists with knowledge about injury prevention partici-pated Two representatives of the Dutch consumer safetyinstitute with expertise on implementation of injury stra-tegies were involved Furthermore the coordinatingresearcher is an international former judo athleteIn the first KTG meeting the possibilities of reducing

injury rates in judo athletes were discussed Potential facil-itators were identified for the adoption and implementa-tion of a judo-specific trainer-based injury preventionprogramme Potential facilitators might be a generalrespect towards the trainer by athletes and the standardwarm-up period at the start of each judo training Potentialbarriersmight be the long-term structural implementationand the various ideas of trainers about the warm-upAs a sidestep of the KTS the coordinating researcher

discussed the content of the two available interventionsthrough individual meetings with five judo experts15 16

The opinion of the judo experts was that relatively fewexercises were dynamic and variation could be improvedand as such exercises were not fully in line with daily judopractice The basic principles of some exercises werefound to be useful for the development of our preventionprogramme on condition that modifications wereapplied These exercises include lunches hop exerciseso-soto-gari exercise plank exercises the superman thepump walk and squat exercises Three extra brainstormsessions were held in judogi on the tatami to modify theseexercises and to create new exercises These sessions wereheld with three judo experts Each brainstorm session wasled by the coordinating researcher All exercises werefilmed All members of the KTG received the videos and

provided feedback about the potential preventive effectand the practical use of the exercises in judo Members ofthe KTG independently rated the exercises on theseaspects before the start of the second KTG meetingIn the second KTG meeting members of the KTG

selected the highest rated exercises to include in the pro-gramme and the lowest rated exercises to exclude from theprogramme In cases of doubt the KTG discussed untilunanimous consensus was reached The expert group pre-ferred the following characteristics with regard to thecontent and form of the exercises of the new interventionprogramme (1) exercises focusing on the prevention ofshoulder knee and ankle injuries Finger injuries are notincluded due to the minor severity (2) a trainer-basedexercise programme to increase adherence as judo athletesoffer respect and obey the judo trainer (3) dynamic exer-cises performed with a partner to create real judo circum-stances and to preserve the pleasure in performing thewarm-up (4) multiple options in exercises so that trainershave autonomy in deciding which exercises to performeach judo training (5) a duration of 10 min with a max-imum of 15 min Each exercise lasting no longer than 1min (6) exercises performed as warm-up prior to the judotraining (7) exercises performed barefoot on the tatamiThe KTG reached unanimous consensus on the con-

tent of the intervention and categorised all exercises bytheir aim (increasing three different aspects of physicalfitness) and three difficulty levels

Step 4 Product developmentThe concept intervention named the IPPON interventionconsisted of 33 exercises in total Trainers were instructedto select 11 exercises in total for each warm-up

Table 1 Summary of the results categorised by the five-step Knowledge Transfer Scheme guidelines

Step Results

1 Problem statement Due to the high incidence rates in judo there is a need for the implementation of an intervention toprevent injuries among judo athletes

2 Evidence description Injury prevention programmeswere found effective in reducing injury rates in other sports For judo noprevention programme has yet been systematically developed and no proven effective injuryprevention programme exists

3 Knowledge TransferGroup

Unanimous consensus on the design and content of the intervention was reached1 Focus on the prevention of shoulder knee and ankle injuries2 Trainer-based exercise programme to increase adherence3 Including dynamic exercises performed with a partner4 Choice from different exercises5 10ndash15 min programme6 Exercises performed as warm-up prior to the judo training7 Exercises performed barefoot on the tatami

4 Productdevelopment

Pilot study Although all exercises were approved by experts and end-users the programme wasextended with three strength exercisesIntervention 36 exercises divided in the categories lsquoflexibility and agilityrsquo lsquobalance and coordinationrsquoand lsquostrength and stabilityrsquo 12 exercises per category with 3 levels of difficulty Use of 4 exercises percategory and 12 exercises in total as warm-up routine

5 Evaluation The effectiveness and feasibility of the Injury Prevention and Performance Optimization Netherlandsintervention will be evaluated in a randomised controlled trial

Tatami judo training ground

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1 Balance and coordination this category consisted of 12exercises During each training athletes wereinstructed to perform four exercises from this category

2 Flexibility and agility this category consisted of 12 exer-cises During each training athletes were instructed toperform four exercises from this category

3 Strength and stability this category consisted of nineexercises During each training athletes were instructedto perform three exercises from this category

Evaluation of the concept interventionThe exercises were evaluated on its feasibility at threedifferent judo schools by three different trainers anda total of 34 judo athletes (21 men and 13 women agerange 12ndash52 years) during a period of 4 weeks The parti-cipants were instructed to perform the programme twotimes per week over the 4-week time period

Outcomes of the observationsThere was sufficient space in the dojos (judo traininghall) to perform all exercises The explanations of theexercises from trainer to athletes were clear and correctExercises were not always performed as intended Thetrainers did not always correct the athletes adequatelywhile there was a substantial observed difference betweenathletes in execution of the exercises

Outcomes of the structured interviewsGeneralStrong components were that trainers were enthusiastic touse the IPPON intervention as warm-up on a regular basis injudo practice Trainers mentioned as positive elements thestructured design pleasure for the athletes and the inclu-sion of exercises targeting all muscle groups Athletes werealso enthusiastic to perform the exercises of the IPPONintervention because of the challenging exercises Itemsfor improvements were that trainers and athletes misseda cardiovascular warm-up at the start of the programmefalling techniques and they suggested to include morestrength exercises

InstructionsThe photo and description cards and the instructionvideo were considered as helpful and relevant by thetrainers Trainers suggested an instruction book withmultiple images more extensive text explanations andthe denotation of key points as possible improvements

Practical useTrainers found the rank order of the included exerciseslogical for the warm-up All exercises with a partner werepreferred to be at the end of the intervention This alsoapplies for the big jump exercises (eg ice-skating exer-cises) Trainers noticed that both low-level and high-levelathletes could perform the exercises

UsefulnessThe opinion of the trainers was that all exercises were poten-tially preventive for reducing injuries Trainers preferred

more variation of the exercises and the possibility to intro-duce additional exercises Athletesmentioned that allmusclegroups were sufficiently addressed performing the interven-tion especially the shoulders and the lower extremity

Time durationThe duration of the warm-up did not exceed 15 min astimed by the trainers All exercises were well timed in 1min as intended

DifficultyAll exercises were rated by the athletes on difficulty ran-ging from 0 (extremely difficult) to 10 (extremely easy)with 5 indicating a perfect level of difficulty Exercises inthe balance and coordination category had a median of 5(range 1ndash9) which indicates a perfect level of difficultyExercises in the flexibility and agility category hada median of 4 (range 1ndash7) which indicates that the exer-cises are slightly difficult Exercises in the strength andstability category had a median of 5 (range 3ndash7) whichindicates a perfect level of difficulty

Modification of the IPPON interventionThe results of the pilot study were discussed in the thirdKTGmeeting Based on these results the KTG formulatedmodifications in terms of thermoregulation and fallingtechniques variation sequence and difficulty of exercises

Thermoregulation and falling techniquesTrainers were instructed to start with running exercises forthermoregulation to increase the heart rate blood flow andlung ventilation and falling techniques (ukemi-waza) toimprove falling skills prior to the intervention exercises30 31

VariationThree additional strength exercises were added to equal-ise the number of exercises in each category as suggestedby trainers In addition to the new minimum of 12 exer-cises as part of the IPPON intervention trainers couldadd their own exercises if their training requires addi-tional warm-up exercises

SequenceThe three categories of exercises were retained althoughthe order of the first two categories (balance and coordi-nation and flexibility and agility) was switched All duoexercises were scheduled at the end of the programmeInstructions were added for trainers to select four exer-cises per category The numbering of the exercises wasremoved as this was wrongly interpreted as the order ofexercises More variation within the programme was cre-ated through the requirement of including two exercisesfor the lower extremity and two exercises for the upperextremity in the balance and coordination category

DifficultyAll exercises were reassessed on difficulty by members ofthe KTG rated by one star (easy) two stars (moderate) orthree stars (difficult) Trainers were instructed to choose

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a difficulty level of the exercises in line with the capacitiesof the group of judo athletes

Final IPPON interventionThe final version of the IPPON intervention (figure 2)consisted of 36 exercises divided into three categories (1)lsquoflexibility and agilityrsquo subdivided in exercises for thelower and upper extremity (2) lsquobalance and coordina-tionrsquo and (3) lsquostrength and stabilityrsquo Each category con-sisted of 12 exercises with three different levels ofdifficulty Trainers were instructed to use 4 exercises percategory and 12 exercises in total as a warm-up Theseexercises focused on the prevention of shoulder knee orankle injuries Trainers were instructed to start with run-ning exercises and falling techniques prior to the inter-vention exercises Available instruction materials werephoto and description cards instruction books andinstruction videos (online supplemental material 5)

Step 5 Evaluation of the interventionThe effectiveness and feasibility of the final IPPON inter-vention will be evaluated in an RCT (NL7698 trialregisternl) Judo athletes will use the IPPON intervention aswarm-up during the season 20192020 All injuries willbe registered with online questionnaires duringa 6-month period The IPPON intervention will be com-pared to usual warm-up during judo training Interna-tional implementation is planned if the IPPONintervention is proven effective in preventing andorreducing injuries in judo

DISCUSSIONWe described the systematic development of an injury pre-vention programme for judo All exercises of the IPPONintervention were positively assessed by trainers and ath-letes in a pilot study with regard to usefulness practical useinstructions duration and difficulty Three strength exer-cises were added based on the outcomes of the pilot study

Development processFor the first step in the development process we searchedthe literature to formulate the injury problem in judoThe reported incidence of injuries in judo varied from1125 to 296 The 3-month prevalence in Dutch recrea-tional judo athletes was 417 The highest injury rateswere finger (30) knee (26) shoulder (22) andankle injuries (14)26 27 The most frequent injurytypes were ligament sprains muscle strains and contu-sions The most common injury mechanism was beingthrown during standing fights (tachi-waza) (85) ofwhich the majority were acute injuries Training injuryrates were higher (70) than the competition injuryrates28 Injuries in judo cause absence of training andcompetitions that varied from 1 to 29 days4 27 29

For the second step in the development process wesearched the literature for injury prevention programmesin judo In 2014 the Judo 9+ injury prevention pro-gramme was published15 This programme consisted of

nine exercises to address balance dynamic stabilisationand core stability In 2015 the Flemish Judo Association(Belgium) introduced an injury prevention programmefor judo athletes16 This expert opinionndashbased pro-gramme consisted of five dynamic and five static exerciseswith a progression in difficulty Both programmes havenot been tested for their feasibility or effectiveness yetModifications to the IPPON intervention were made

after completing the pilot study The literature supportedthe need expressed by trainers and athletes to increasethe body temperature prior to the interventionexercises30 and to improve falling skills as most injuriesin judo are associated with the lack of falling skills31

Further we created an instruction book improved thephoto and description cards and renewed the instructionvideos to ensure that all exercises are performedcorrectly

Injury prevention programmes across sportsThe practice- and evidence-based IPPON intervention forjudo has many similarities with other proven effectiveinterventions Evidence-based injury prevention pro-grammes have been developed in several sports like foot-ball rugby and basketball10 11 13 Effectiveness studies oninjury prevention programmes have commonly been con-ducted in team sports10 11 13 The BokSmart Safe Sixintervention is an injury prevention programme devel-oped to reduce injuries in the lower extremity and theshoulder among rugby players32 Comparable to our exer-cises these exercises focus on increasing strength stabi-lity and balance These elements are also comparable tothe exercises in the FIFA 11+ intervention programme12

The FIFA 11+ is an injury prevention programme devel-oped to reduce injuries among football players aged14 years and older It consists of 15 exercises focus onincreasing strength plyometrics and balance RCTsshowed a decrease in injuries of 50 among male playersand 35 among female players12

Effectiveness studies on injury prevention programmesin individual sports are limited Available RCTs con-ducted among running athletes did not reduce injuryrates33ndash35 These programmes contained elements of sta-tic stretching or off-season exercises Static stretching hasnot been proven effective36 Implementation of in-seasonprevention is essential for injury prevention13 Hence thefundamentals of these exercises are different comparedto our intervention Another difference is that there is ingeneral no adequate supervision of the exercises in indi-vidual sports Although judo is an individual sport alltraining is supervised by a trainer or coach Coach-basedinterventions raise the adherence which is important forsuccessful implementation37 38

KTS methodologyThe methodology for the development of the IPPONintervention was guided by the KTS14 The KTS hasbeen designed for the direct translation of evidence intopractice in sports injury prevention This methodology

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Figure 2 The final version of the Injury Prevention and Performance Optimization Netherlands intervention

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has previously been used for the development of a tennis-specific injury prevention programme for tennis players(TennisReady)20 TennisReady consists of an on-courtand off-court warm-up programme based on cardiovascu-lar neuromuscular and tennis-specific exercises Thecontent of those exercises corresponds to the exercisesin our programme We start with cardiovascular manage-ment and continue with neuromuscular exercises andjudo-specific exercises in three different domainsIn our hypothesis we asserted that we could develop

a practically applicable injury prevention programmeusing the KTSWe succeeded in systematically developingan injury prevention programme for judo tested in a pilotstudy The most important results were the eagerness oftrainers and athletes the perceived usefulness and thecorrect level of difficulty Based on these results theintervention is suitable for evaluation of its effectivenessto reduce injuries Using the KTS for this process resultedin strengths as well as some limitations

StrengthsThe strengths of the KTS are the use of a bottom-upapproach for the development of the intervention Inter-ventions are developed using evidence-based informationand practical experience to increase effectiveness whichis important for successful implementation Representa-tion of practice was guaranteed by the multidisciplinaryKTG and by the expertise and experience of end-usersparticipating in the pilot study The multidisciplinaryKTG had a key role in the translation of evidence intopractice actions All 14 members of the KTG contributedto their specific expertise andor experience

LimitationsThere were some limitations in the process using the KTSguidelines The second step of the KTS (evidence descrip-tion) describes the available scientific evidence to deter-mine the advantage of the intervention Availableevidence on effective injury prevention programmes inother sports and on the prevention of the most frequentinjuries in judo was used in the KTS process12 39 40 As noevidence was available on the effectiveness of injury pre-vention strategies in judo evidence was collected throughexpert opinions during individual and group meetingsAnother limitation in the fourth step of the KTS (productdevelopment) is a missing re-evaluation of the adjustedexercises based on outcomes of the pilot study Howeverthe KTG considered the changes so minor that re-evaluation was not required

CONCLUSIONWe developed a judo-specific injury prevention pro-gramme (IPPON intervention) using the systematic gui-dance of the KTS by means of experts aimed to preventandor reduce the occurrence of shoulder knee andankle injuries among judo athletes The trainer-basedintervention consists of 36 exercises classified into threecategories (1) flexibility and agility (2) balance and

coordination and (3) strength and stability The pro-gramme should be performed minimal two times perweek at the start of the judo training The developmentof this judo-specific injury prevention programme is thepreliminary step in solving the injury problem The effec-tiveness and feasibility of the final IPPON intervention oninjury reduction among judo athletes should be demon-strated before wide-scale implementation

Author affiliations1Amsterdam UMC University of Amsterdam (UvA) Department of OrthopaedicSurgery Amsterdam Movement Sciences (AMS) Amsterdam The Netherlands2Academic Center for Evidence-Based Sports Medicine (ACES) Amsterdam UMCAmsterdam Movement Sciences (AMS) Amsterdam The Netherlands3Amsterdam Collaboration on Health and Safety in Sports (ACHSS) Amsterdam UMCIOC Research Center of Excellence Amsterdam The Netherlands4Department of Public and Occupational Health Amsterdam UMC VU UniversityAmsterdam Movement Sciences (AMS) Amsterdam The Netherlands

Twitter Evert Verhagen evertverhagen Johannes L Tol Jltol and Gino M M JKerkhoffs KerkhoffsG

Acknowledgements Special thanks to all experts involved in the development ofthe intervention Benny van den Broek Arnold Brons Jessica Gal Vincent Goutte-barge Ronald Joorse Ellen Kemler Kai Krabben and Jeroen Mooren Also thanks toall judo trainers and judo athletes for their participation in the pilot study

Contributors All authors were involved in the development of the programme AVGwas responsible for drafting the manuscript All authors reviewed and agreed on themanuscript

Funding This study was financially supported by The Dutch Organization for HealthResearch and Development (ZonMw) with project number 50-53600-98-112

Competing interests None declared

Ethics approval The medical ethics committee of the Academic Medical CenterAmsterdam granted exempt status (qualified as non-WMO obliged researchW19_071) The study protocol was registered in the Dutch trial register (NTR 7698)

Provenance and peer review Not commissioned externally peer reviewed

Data availability statement All data relevant to the study are included in the articleor uploaded as supplemental information

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

Open access This is an open access article distributed in accordance with theCreative Commons Attribution Non Commercial (CC BY-NC 40) license whichpermits others to distribute remix adapt build upon this work non-commerciallyand license their derivative works on different terms provided the original work isproperly cited appropriate credit is given any changes made indicated and the useis non-commercial See httpcreativecommonsorglicensesby-nc40

ORCID iDsAmber L von Gerhardt httporcidorg0000-0002-1226-1991Ingrid Vriend httporcidorg0000-0001-9605-4019Evert Verhagen httporcidorg0000-0001-9227-8234Johannes L Tol httporcidorg0000-0001-5322-8445Gino M M J Kerkhoffs httporcidorg0000-0001-5916-7049

REFERENCES1 IJF (International Judo Federation) Available httpwwwijforg

(accessed on 18 Jun 2019)2 Torres-Luque G Hernaacutendez-Garciacutea R Escobar-Molina R et al

Physical and physiological characteristics of judo athletes an updateSports 2016420

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3 Kim KS Park KJ Lee J et al Injuries in national olympic leveljudo athletes an epidemiological study Br J Sports Med2015491144ndash50

4 Souza M Monteiro H Del Vecchio F et al Referring to judorsquos sportsinjuries in Satildeo Paulo State Championship Sci Sport 200621280ndash4

5 Akoto R Lambert C Balke M et al Epidemiology of injuries in judo across-sectional survey of severe injuries based on time loss andreduction in sporting level Br J Sports Med 2018521109ndash15

6 Pierantozzi E Judo high level competitions injuriesMedit J Musc Surv20091726ndash9

7 TNO Blessures judo en jiu-jitsu (BIS) TNO Kennis Voor Zaken20182138ndash42

8 Raysmith B Drew M Performance success or failure is influencedby weeks lost to injury and illness in elite Australian track and fieldathletes a 5-year prospective study J Sci Med Sport201619778ndash83

9 Lohmander L Englund P Dahl L et al The long-term consequence ofanterior cruciate ligament and meniscus injuries osteoarthritis AmJ Sports Med 2007351756ndash69

10 Vriend I Gouttebarge V Finch CF et al Intervention strategies used insport injury prevention studies a systematic review identifying studiesapplying the Haddon matrix Sport Med 2017472027ndash43

11 Schiff M Orsquohalloran R Schiff M et al Injury prevention in sports AmJ Lifestyle Med 2010442ndash64

12 Bizzini M Dvorak J FIFA 11+ an effective programme to preventfootball injuries in various player groups worldwide - a narrative reviewBr J Sports Med 201549577ndash9

13 Leppaumlnen M Aaltonen S Parkkari J et al Interventions to preventsports related injuries a systematic review and meta-analysis ofrandomised controlled trials Sport Med 201444473ndash86

14 Verhagen E Voogt N Bruinsma A et al A knowledge transfer schemeto bridge the gap between science and practice an integration ofexisting research frameworks into a tool for practice Br J Sports Med201448698ndash701

15 Malliaropoulos N Callan M Johnson J Comprehensive trainingprogramme for judo players nine plus 9+Muscles Ligaments TendonsJ 20144262ndash8

16 VJF (Vlaamse Judo Federatie) Available httpswwwvjfbenlclubsprojectengezond-ethisch-sportenongevallenpreventie-het-judo(accessed 26 Feb 2019)

17 Verhagen E If athletes will not adopt preventive measures effectivemeasures must adopt athletes Am Coll Sports Med 20127ndash8

18 Finch C A new framework for research leading to sports injuryprevention J Sci Med Sport 200693ndash9

19 Van Tiggelen D Wickes S Stevens V et al Effective prevention ofsports injuries a model integrating efficacy efficiency compliance andrisk- taking behaviour Br J Sports Med 200842648ndash52

20 Pas HIMFL Bodde S Kerkhoffs GMMJ et al Systematic developmentof a tennis injury prevention programme BMJ Open Sport Exerc Med20184e000350

21 Gouttebarge V Zuidema V Prevention of musculoskeletal injuries inrecreational field hockey the systematic development of anintervention and its feasibility BMJ Open Sport Exerc Med 20184e000425

22 Minghelli B Isidoro R Prevalence of injuries in Jiu-Jitsu and Judoathletes of Portugal South associated injury mechanismsJ Community Med Health Educ 20166(3)

23 James G Pieter W Injury rates in adult elite judoka Biol Sport20032025ndash32

24 Green CM Petrou MJ Fogarty-Hover MLS et al Injuries amongjudokas during competition Scand J Med Sci Sport 2007

25 Junge A Engebretsen L Mountjoy ML et al Sports injuries during theSummer Olympic Games 2008 Am J Sports Med 2009372165ndash72

26 Gal JSI van der Made AD Kneepkens HE et al Sporttraumatologie inhet judo Ned Tijdschr Voor Traumatol 20132163ndash8

27 Pocecco E Ruedl G Stankovic N et al Injuries in judo a systematicliterature review including suggestions for prevention Br J Sports Med2013471139ndash43

28 Kujala UM Taimela S Antti-Poika I et al Acute injuries in soccer icehockey volleyball basketball judo and karate analysis of nationalregistry data Br Med J 19953111465ndash8

29 Jaumlggi U Joray CP Bruumllhart Y et al Verletzungen in denKampfsportarten Judo Taekwondo und Ringen - Eine systematischeUumlbersichtsarbeit Sportverletzung-Sportschaden 2015

30 Racinais S Cocking S Peacuteriard JD Racinais S Cocking S et al Sportsand environmental temperature from warming-up to heating-upTemperature 20174227ndash57

31 Kamitani T Malliaropoulos NG OmiyaM et alOn the way to the TokyoSummer Olympic Games (2020) Prevention of severe head and neckinjuries in judo itrsquos time for action Br J Sports Med 2017511581ndash2

32 Sewry N Verhagen E Lambert M et al Evaluation of the effectivenessand implementation of the BokSmart Safe Six injury preventionprogramme a study protocol Inj Prev 201723428

33 Van MechelenW Hlobil H Kemper HCG Kemper HC et al Preventionof running injuries by warm-up cool-down and stretching exercisesAm J Sports Med 199321711ndash9

34 Buist I Bredeweg SW Van Mechelen W et al No effect of a gradedtraining program on the number of running-related injuriesa randomized controlled trial Am J Sports Med 2008(2)33ndash39

35 Bredeweg SW Zijlstra S Bessem B et al The effectiveness ofa preconditioning programme on preventing running-related injuries innovice runners a randomised controlled trial Br J Sports Med201246865ndash70

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38 GoodeAP ReimanMPHarris L et alEccentric training for prevention ofhamstring injuriesmay depend on intervention compliance a systematicreview and meta-analysis Br J Sports Med 201549349ndash56

39 Pasanen K Parkkari J Pasanen M et al Neuromuscular training andthe risk of leg injuries in female floorball players cluster randomisedcontrolled study Br J Sports Med 200842502ndash5

40 Olsen OE Myklebust G Engebretsen L et al Exercises to preventlower limb injuries in youth sports cluster randomised controlled trialBr Med J 2005330449ndash52

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