Injuries in karate : a review

mostly recorded in the area of head, face and neck. Modifications of the fighting regulations reduced injury risk during championships. However, the risk decline was observed only for minor injuries. Conclusion It is important to investigate the factors that reduce injury risk in sport. In karate, injuries are impossible to be entirely eliminated as the impact that exceeds tissue mechanical strength has not been excluded as the main cause of severe injuries. Among children, formal exercise (kata) and pre-arranged sparring might represent a safe alternative for karate fights.


Introduction
There are three groups of combat sports, depending on the actions permitted with fighting regulations: Group 1: using weapon as in fencing; Group 2: using punches and/or kicks as in boxing, karate or taekwondo and Group 3: using throws, pinning techniques, strangulation and joint manipulation techniques 1 .All the three types of motion actions can be also mixed in ju-jitsu 2,3 .Undoubtedly, practicing combat sports is risky.Average rates (percentages of injured athletes of 36 Olympic sports) were similar in male (12.1%) and female (13.3%) athletes.The rates of injuries in fencing were 13.1% and 5.6% in males and females, respectively.Opposite patterns were observed in boxing, i.e. 7.3% and 19.4%, in males and females, respectively.The injury risk (IR = #injuries/#athletes) was the highest in males (51.6%) and females (26.6%) taekwondo (which can be regarded as a Korean variant of karate) and was medium in male (10.9%) and female (12.4%) judo athletes.IR in wrestling was also medium, i.e. 10.5% in males and 13.2% in females 4 .Injury is a factor that causes trouble winning 5,6 .
Similarly to taekwondo, boxing, judo and wrestling, which are Olympic combat sports, the participants of karate competitions fight in gender, age and weight categories [7][8][9] .Karate fighting is considered a highintensity event 10 .Different karate styles are becoming more and more popular because training regimes are oriented at preparation for fighting during competitions.World Karate Federation is the largest international governing body of this sport with over 130 member countries and has more than 10 million members 11 .With this high number of karate practitioners, it seems very important to prevent injuries.Similar to other sports, identification of the relationship between the causes and the effects of accidents is very important for the activities aimed at reduction in the injury risk 12 .It is suggested that in retrospective (R) epidemiological studies analysis is carried out from the effect towards the cause.However, in prospective (P) studies, analysis is typically conducted from the cause towards the effect 13 .There have been the findings of the retrospective studies in institutions providing insurance 14 in hospitals 15 and questionnaire studies among karate athletes who provided information about injuries in a particular time period 16 .It is essential to combine activities of an observer of an injury mechanism (karate expert) and a person who diagnoses (medical doctor), which is especially important during P studies 17,18 .The seriousness of the problem of injuries in karate has been supported by the publications which presented injury rates, injury types and location, and injury

Materials and methods
A comprehensive search in international databases of MEDLINE, Web of Science, SPORTdiscuss, Academic Search Premiere, Google Scholar was conducted to find the results matching the keywords 'karate', 'injury', 'retrospective' and 'prospective'.The analysis excluded the data concerning infrequent cases of injuries.Finally, 20 peer reviewed studies were qualified.They described specific characteristics of injury, such as rates, types, locations, mechanism of injury.Number of injuries reported in different studies ranged from 12 cases 19 to 7431 cases 15 .Absolute and relative injury rates (IR) were evaluated in different groups of karatekas.Relative injury risk (IRR) was adopted as a ratio of IR in the Group 1 to IR in the Group 2 used in epidemiology 13 .For the results of retrospective and P studies, the authors calculated IRR risk in consideration of gender, age and sports skill level.Type, location and mechanism of injury percentages were presented and compared.

Results
Injury rate in male and female karate athletes Table 1 presents incidence of injuries documented in the literature from years 1977 to 2012.
Various indices were used to identify the scale of injury rate in karate.Hence the results and their evaluation seemed to be ambiguous.The findings obtained in the retrospective studies based on institutional documentation (RD) show that the injuries were most frequently observed in men (aged 16-32 years), chiefly during training, while the relative injury rate was 1.95 per 1000 participants per year 14 .In another study, absolute IR in training was also much higher than the rate of injuries occurring in competitions 20 .A significantly higher IR was also observed in the group of males compared to females.The highest IR was found for the athletes aged 20-24 years (95% CI criterion) 20 .The youngest karateka in RD record was nearly 14 months 15 .In retrospective studies based on questionnaires (RQ) among adult women, contributions of training vs. competition injuries were nearly fifty-fifty 21 .In another RQ study, in a club where sparring and competition were not the main training goal, IR in children (aged 6-16 years) was 3.7 injuries per 1000 h of karate training.IR depended on the experience, training hours and rank rather than on age and gender 22 .IR during competition for young karatekas (aged 7-15 years) was considerably higher, i.e. 13.3-15.3injuries/100 minutes of athletic exposure (AE), whereas IR value in girls was higher than in boys 19 .
Among the P studies that investigated injury rate during karate competitions, the most popular measure was IR expressed per 1000 AE.The value of #injury/1000 AE in male tournaments ranged from 22.2/1000 AE 23 to 194.0/1000 AE 18 .In female athletes, IR was from 66.2/1000 AE 24 to 143.2/1000 AE 25 .The results of observation of karate tournaments recorded by the same authors of P studies provided information about the effect of different factors on the level of IR which was not fully consistent.As a result of application of protective gear in male competition, a four-time reduction in IR was demonstrated (per 100 karate matches) 23 .Other observations did not confirm the optimistic prognosis that resulted from these studies 18,26 .When knuckle padding was used in male tournaments, the IRR was similar as without this type of protective gear 26 .In an international Oyama's Cup (Kyokushin full-contact style), despite the obligatory use of the protective gear (foot and shin), IR was higher (194.0/1000AE) compared to the national-level tournaments where this gear was not used (148.6/1000AE), with IRR being 1.31 18 .Elevated IR (192.6/1000AE) was also observed in the members of the male national team that competed in the selection tournaments in the lead up to Asian Karate Championships 2012 27 .High sport rank of the Oyama's Cup might have affected the increase in IRR with respect to the national-level competition.
Adult males were characterised usually by higher IR compared to women that presented the same competitive level 21,24,25,29,30 .A decline in IR during world championships organised by the World Karate Federation as a result of changes in fighting regulations was observed.Consequently, IRR (post-value in relation to prevalue) was 0.64 and 0.46 in males and females, respectively 24,25 .In another study, before using protective gear, IR in males was slightly different than IR in females, with IRR that reached 1.05.Using protective gear caused a higher IR in female than male athletes (IRR = 0.81) 30 .Employing an original and more precise index (#injures/100 minutes AE), however, showed that IR was lower in male athletes (0.83) 30 .With protective gear, IRR (males to females relation) decreased to 0.73 30 .In the age category under 18 years in general, the competitors fought significantly safer after the changes in rules had been implemented (IRR = 1.55; preto post-IR's relation) 30 .to 71.4% 14 .However, the contribution of sprains and strains ranged from 11.9% 14 to 44.7% 20 .They were also in contrast to the rate of contusion (from 0.0% 14 to 35.1% 20 ) and luxation (from 0.0% 14 to 25.4% 30 ).It was found in RD studies that 17.9% of the patients necessitated hospitalisation that took from 2 to 21 days.In 60.0% of the people, bodily injuries were evaluated (according to Polish regulations) as 1%-9% whereas in 20%, medical board evaluated injuries as 10%-15%.Twenty percent of the injured karatekas were evaluated as returned to entirely healthy status 14 .The documentation analysed in RD studies confirmed the fact that it is severe injuries which are reported to hospitals and insurance institutions.The RQ studies did not find concussions, which were rather rare in RD and P studies of karate practitioners.In RQ studies, diagnoses might have been inaccurate since they originated from the injured people rather than from competent doctors.

Injury types Distribution of the frequency of typical injuries depended on the study design (Table 2). Percentage comparison of the injury types showed much
P studies recorded a higher variety in the classification of sustained injuries than R studies.In P studies, the vast majority of injuries were contusions, except for the studies where authors were focused on severe injuries.The most frequent among time-loss injuries were fractures (58.3%) and, also frequent, concussions (8.3%) 32 .Moderate and severe injuries contribution was only 12.9% of all 497 injuries recorded among elite competitors.In the area of head injuries (n = 64), the highest percentage was found for fractures (31.3%) and concussions (28.1%) 24 .Frequency of typical injuries depended on the tactical situation, for example, contusions were more frequent in the attacking (81.1%) compared to the attacked athlete (48.7%).The specific injuries, which occurred exclusively in the attacked athletes included concussion (9.3%) and wind knocked out (9.3%) 18 .

Injury location
Karate injuries reported in RD studies concerned mainly head, face and neck 14 as well as upper and lower limbs 15,20 (Table 3).In RQ studies, the percentage of head, face and neck injuries ranged from 5% in children 22 to 32.4% in adults 16 .Adult men were more often injured in the head, face and neck compared to women (32.4% vs. 9.2%), among which the most frequent were lower limbs injuries (28.5% vs. 53.7%) 16,21.In P studies, head, face and neck injuries accounted for 22.9% 18 to 92% 26 .Contribution of injuries of trunk, upper limbs and lower limbs ranged from 4% 26 to 31.8% 18 , 10.1% 27 to 17.2% 24 and 3.4% 27 to 55.2% 18 , respectively.During the Oyama Cup, where protective gear for feet and shin, the contribution of injuries in the head, face, neck and trunk was increased compared to the injuries reported in the national-level competition where protective gear was not used 18 .Similar patterns were observed in a Danish research, but they concerned an increase in the frequency of head, face and neck injuries 26 .During karate tournaments, both for women and men, predominant injuries were head, face and neck injuries (55.4% vs. 57.9%) 27,29.Moreover, 15-year-old girl and boy karate athletes had also considerable risk of head injury, i.e. 43.8% vs. 52.6%,respectively 19 .

Causes and mechanisms of karate injuries
The circumstances in which injuries occurred were frequently identified as punches, kicks, blocks and falling on the ground.In general, it can be concluded that the impact that exceeded tissue strength led to body damage among karatekas.The most frequent mechanism in RD studies was the impact that occurred during kicks (33.3%) in the head, in the lower limb, groin, stomach and punchbag, falling on the ground (25.6%), hitting with the upper extremity (20.5%) against the head, upper limb, a wall or a board 14 .Mechanism of the injury during kicking was formed through being kicked (26.9%), falling (20.8%) and kicking (18.0%) 15 .In another study, the cause of the body injuries in karatekas were: kick/foot strike (38.0%), fall/ throw/jump (26.0%), block (9.0%), weapon (5.0%) and others (12%) 31 .In RQ studies, the most frequent injury mechanism occurred with kicks (47.0%) and punches (43.2%), whereas it was observed less often for falling on the ground (9.8%) 16 .The predominant causes of injuries in P studies were punches (from 48.4% 28 to 82.7%) 25 .Therefore, kicks were less frequently recognised as an injury mechanism, i.e. from 7.3% 25 to 29.2% 27 .Some authors reported injuries during blocking the attack with the frequency of 5.1% 27 -18.8% 19.

Death cases
Death cases should be analysed if they are typical of a particular sport or, if not, when they occurred during competition or athletic training 33 .In Japan, only one death case was reported.It occurred as a result of a karate punch at the Ritsumeikan University 34 .Three deaths were reported in the USA as a result of blunt injury of the chest.The first death occurred during taekwondo fighting caused by a kick performed by a coach to the lateral part of the chest, the doctors found rib fracture (5th rib on the left), pulmonary oedema, congestion and hepatic exudate.The suffocation was caused by the ingested matter sucked into the trachea.In the second case, a Kempo practitioner received a series of punches on the chest during his tournament fight.It was in the late evening when he was taken to the hospital because of the serious pain and vomiting, and the doctors diagnosed ruptured spleen and infectious mononucleosis.The latter illness might have caused the spleen oedema, making it extremely susceptible to injuries.The patient died one hour after a surgical intervention.The third case occurred during the fight with an advanced fighter.The patient received a light roundhouse kick into the solar plexus.Although resuscitation was performed in the ambulance, the death was recorded after the arrival to the hospital.Stimulation of the vagus nerve, which caused cardiac dysrhythmia, eventually led to cardiac arrest and was found to be the cause of the death.The doctors found the effusion to the soft tissue surrounding the vagus nerve, numerous petechiae in the liver, numerous haematomas in the lung lobes and emphysema of both lungs.All the three cases concerned young men with training experience below one year 35 .
In Poland, a death accident was reported for a 17-year-old participant of a training unit.He had one-year training experience and low level of advancement in Kyokushin karate (8th kyu).Practice fights were performed during the training session under supervision of a coach and according to the regulations which exclude attack to the face.The students were wearing boxing helmets and shin guards.When choosing the partners, the coaches divided students according to the age and body height.At the end of the classes, the patient was fighting with an opponent aged 18 years, with training experience of over two years and 6th kyu rank.The dangerous accident took place when this person was in the corner