Injuries in karate: a review

Injury rate in male and female karate athletes

Table 1 presents incidence of injuries documented in the literature from years 1977 to 2012.

Table 1 Injury rates in karate

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 RQstudy, 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. 13.3-15.3 injuries/100 minutes of athletic exposure (AE), whereas IRvalue 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 Pstudies 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 (148.6/1000 AE), with IRR being 1.3118. Elevated IR (192.6/1000 AE) 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 pre-value) 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 higherIR 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; pre- to post-IR's relation)^[30]. Changes in rules caused a significant reduction in IR during male and female tournaments^[24,25,30], which, however, did not affect the frequency of moderate and severe injuries^[24].

Injury types

Distribution of the frequency of typical injuries depended on the study design (Table 2). Percentage comparison of the injury types showed much more frequent fractures observed in RD studies, i.e. from 16.9%^[20] 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 RQstudies did not find concussions, which were rather rare in RD and Pstudies of karate practitioners. In RQ studies, diagnoses might have been inaccurate since they originated from the injured people rather than from competent doctors.

Table 2 Types of injuries in karate practitioners

P studies recorded a higher variety in the classification of sustained injuries than Rstudies. In Pstudies, 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 RDstudies concerned mainly head, face and neck14 as well as upper and lower limbs^[15,20] (Table 3). In RQstudies, 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 Pstudies, 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].

Table 3 Injury location in karate practitioners

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 Pstudies 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 oneyear^[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 of the fighting field and moved to the right, turning a little backward to the movement direction. At this moment, he received a roundhouse kick to the back of the head. After making a few steps, he staggered but was supported. Then, he lost consciousness for ca. 3 minutes. After the doctor arrived, he was immediately transferred to the local hospital, where he was diagnosed with head contusion and concussion. RTG images did not show changes. The opinion of the surgeon after opening the skull was that the thickness of occipital bone was 3-4 mm while the muscles of the nape of the neck were too weak with respect to the age and overall body build. This might have been conducive to craniocerebral trauma. The patient died on the 5th day after the accident. Its cause was contusion and cerebellar tear^[14]. Physical modifications after head injuries caused by accelerations usually result in elastic deformation of the skull, rapid acceleration of the head motion and the relative motion of the brain with respect to the skull bones^[36]. A specific characteristic of the above accidents was that they occurred during the fight and concerned beginner karatekas. The ability to control the fight remains the basic criterion of the exams for individual ranks.