Discussion
During the Olympic Games in 2008 and 2012, an average injury risk of about 11–12% has been observed. Sprains, strains and contusions, usually of the knee, shoulder and fingers, were the most frequently reported injuries, whereas being thrown was the most common injury mechanism.
The injury risk during the two most recent SOG of about 11–12% is well in accordance with the average injury risk of 11% for all sport disciplines together in the 2012 SOG. In comparison, taekwondo had the highest injury risk with 39.1% during the London Games while in archery, canoe slalom and sprint, track cycling, rowing, shooting and equestrian sport less than 5% of athletes were injured.
Compared with other Olympic combat sports, judo time-loss injury risk of 6–9% during the last two SOGs was clearly lower than in taekwondo (16–18%) but slightly higher than in boxing (4–8%) and wrestling (5–6%), respectively.
It is notable that diverging results were influenced by different study designs and definitions of injury: retrospective studies showed a higher percentage of injuries as they usually cover entire careers of judokas until the moment of the questionnaire, while prospective studies are generally oriented to shorter and well-defined periods.
Influence of Nutrition, Hydration and Weight Cycling on Judo Injuries
Although nutrition, hydration and weight cycling are considered important injury risk factors in combat sports, specific research on judo is still very scarce. A higher frequency of injuries and impairment of muscular function have been found in weight cycling judokas and among those undergoing rapid weight reduction before a competition compared with control groups of judo athletes. Moreover, even if bone injuries were not higher in judokas displaying disordered eating behaviours, the higher risk of bone injuries due to changes in bone metabolism has been referred as a consequence of weight cycling in judo. Nevertheless, the strength requirements and technical characteristics of judo practice may also be preventive factors for bone loss and bone-related injuries. Furthermore, it has been reported that the fluid restriction practiced by many judo athletes when involved in weight loss processes, in conjunction with intense judo training in hot environments, resulted in serious dehydration, which might provoke heat-related injuries. Death has rarely been reported as a consequence of dehydration in judo and wrestling.
Despite the described risks, most judo athletes reduce their weight a short time before competition. The methods used include fluid restriction, sauna or plastic clothing, diuretics or laxatives, or food restriction, among others. In line with Artioli et al, it can be concluded that athletes, especially prepubescent ones, must avoid harmful weight loss procedures in terms of sports injury prevention and further actions, including specific programmes, must be promoted to dissuade judo athletes from these methods. Judo should follow the example of wrestling, where these programmes started to be implemented since the late 1990s. To create a daily energy deficit of 500–1000 kcal, a long-term soft diet and aerobic exercise have been recommended for losing weight without harming the athletes' health. More importantly, strict regulations would be the best way to avoid dangerous weight loss practices in judo, as has been the case for wrestling.
Psychological Factors Associated With Judo Injuries
The research results of recent years reinforce the assumption that psychological factors are involved in the development of sports injuries. The perceived similarity and control seem to directly contribute to the perceived risk of injury. The perceived similarity of an athlete with the 'typical judoka who gets injured while practicing judo' might especially be a pathway to the time and effort spent in analysing the risk information critically, which might lead to developing preventive actions. Some studies in non-judokas refer to the three central elements of self-determination theory (autonomy, competence and relatedness) fostering intrinsic motivation and seem to be related to the return to sport following injury. Accordingly, there is preliminary evidence that positive psychological responses (motivation, confidence and low fear) are associated with a higher rate of returning to sport.
Future research on judokas should aim at reducing injuries by testing cognitive behavioural strategies, which have shown efficacy in other sport settings, by performing randomised clinical trials based on the extended theoretical framework of stress-injury models.
Injury Prevention Measures During Training and Competition
The knowledge on judo injuries is indispensable for the development of preventive measurements.
Considering the relatively high frequency of upper body injuries being thrown in judo, to improve falling skills, by means of good and frequent break fall training, avoiding to fall on the top of the shoulder or on the palm of the hand, should be the highest priority of judo coaches, especially when teaching beginners and young practitioners. Also, balance training as well as testing the training effects in young judokas might be useful in the evaluation and reduction of the risk of falls. As throwing could also be dangerous, throwing techniques should likewise be carefully and correctly apprehended from the very beginning. Furthermore, it is important to have good physical preparation, especially by stimulating long-term resistance training practice, mainly focusing on women's upper body strength, as a high level of strength and flexibility showed a significantly lower injury rate.
A specific programme for ACL injury prevention with proprioceptive exercises and knowledge of the risk situations, in addition to a higher emphasis on bilateral grips during training, would be useful in reducing knee injuries. Changing the rules, including the prohibition of direct attacks with the hand on the pants, seems to reduce knee sprains. However, this should be assessed more extensively in future studies. Yamamoto et al showed elastic taping to have a preventive function on ankle instability. Additionally, the quality of the mat is also important: even if collisions, that is, head impacts, would be attenuated on relatively soft mats, the feet would penetrate into the mat, which could lead to knee ligament injuries. A soft protective headgear could be an option to decrease head injuries as well as 'cauliflower ear'. The frequency of finger injuries has to be assessed in future follow-up studies to determine if the recent changes in the international judo rules from 2013 concerning grip fight will have a positive influence.
Educational Programmes
Injury prevention can be improved by providing education for athletes, coaches, referees and tournament directors and establishing minimum standards of qualification and experience for trainers and referees. They should also be instructed in the mechanisms, prevention and treatment of injuries. Furthermore, judokas need to be aware of the importance of entering competition fully recovered from past injuries. In addition, one decisive criterion of the ability to compete could be the scores in the Special Judo Fitness Test (SJFT). During the rehabilitation process, judo coaches can compare individual progress in SJFT, aiming at the achievement of the scores athletes had before sustaining the injury. Moreover, athletes should be encouraged to give up on time in case of armlocks and choking techniques as well as to interrupt the fight in case of moderate injuries. On the other hand, the role of the referee is also relevant, especially during armlocks and choking techniques, stopping the fight if the athlete is unable to give up.
It is also necessary to reflect on the re-evaluation of the current competition rules. Specific rules should keep on developing for the young categories having safe practice as a main concern. Hard or uncontrolled throwing, holding, joint locking or choking techniques and dangerous falling techniques, for example, trying to avoid falling on the back, can cause injuries and even serious damage, and should be strictly penalised for the preservation of young athletes' health. Moreover, children and juveniles or inexperienced judokas should be prevented from entering competition prematurely. Competitions for athletes of different levels of experience, as those organised by the French Judo Federation, should be encouraged.
A correct pedagogical approach should not be forgotten. Studies on sports traumas indicate that the injury risk is lower if goals of achievement are proposed to players: sport exercise for health, physical maintenance or pleasure causes 9% fewer accidents than practice driven by aspiration of good performance, success in competition or desire of taking risks. Therefore, a reorientation of performance goals to goals of achievement, especially for young judo practitioners, would probably reduce the injury risk.