KEY WORDS: Karate, martial arts, athletic injuries, risk factors, safety, sports.

Participation in the martial arts has increased dramatically over the past 15 to 20 years (Oler et al., 1991; Pieter and Lufting, 1994). Karate is one of the most widespread martial arts and the Japanese word "karate", meaning empty hand (kara = empty, te = hand), describes the property of this sport involving the use of punches, kicks and blocking techniques without the use of weapons. Shotokan karate is one of the oldest styles of karate and was first publicly demonstrated in Japan in 1922 by its modern day founder Funakoshi, though it had originated from the Japanese island of Okinawa in 16th century (Stricevic et al., 1983).

Shotokan karate is among the more popular art forms, with a conservative estimate of 2 million participants worldwide (Oler et al., 1991). Shotokan karate is considered noncontact, in which punches and kicks must be controlled (without injury to the opponent) or stopped before contact with the opponent's body. Correctly executed techniques to the head or trunk are scored. For uncontrolled punches and kicks, the competitor receives a penalty and the opponent wins a point. Sparring in tournaments is often more aggressive, therefore mouth guards and lightweight sparring gloves are worn (Violan et al., 1997).

Modern non-contact karate tournament competitions consist of two disciplines: kata and kumite. Kata is a set combination of techniques which are practiced with imaginary opponents, and kumite is the term used for sparring with an opponent and ranges from prearranged moves for beginners to "free fighting" for experienced practitioners and for use in competitions (Frederic, 1995). Other benefits to competing in karate include, improved flexibility, strength, and balance (Violan et al., 1997), increases agility, and decreases reaction time (Layton, 1993). It also is proposed to enhance qualities such as respect, politeness, discipline, concentration, patience, power of observation and self-confidence (Fetto, 1994; Daniels and Thornton, 1990; Daniels and Thornton, 1992).

Increasing numbers of women are taking part in martial arts in order to maintain fitness and provide skills for self-defence all around the world (Zetaruk et al., 2005). In Iran, the popularity of martial arts including Shotokan karate is more evident among women, because they can join in this sport without contravening their Islamic beliefs regarding use of covered garment and scarf and so they can participate in national and sometimes international sports events.

As a martial art, Shotokan karate may be perceived as carrying a high risk of injury as the aim is to strike the opponent. Although several articles regarding karate injuries have been published, although the generalisability of findings is limited by the research design used. Studies include case reports (Arriaza et al., 1990; Ortu et al., 2006) and retrospective studies (Birrer and Halbrook, 1988; Zetaruk et al., 2000a; Destombe et al., 2006; Tuominen, 1995). Research into the injury and karate performance is relatively widespread with some studies conducted in training (Zetaruk et al., 2000b) and others in competition (Muller-Rath et al., 2000; Stricevic et al., 1983; Macan et al., 2006). Further, some studies have compared injury risk in a range of martial arts and not only karate (Birrer, 1996; Birrer and Halbrook, 1988) or compared the injury risk of karate with other martial arts (Zetaruk et al., 2005; Oler et al., 1991). Despite the number of studies, it is proposed a consistent pattern of results does not exist.

The aim of the present study was to document the injury rate and patterns in Iranian women competitive Shotokan karate athletes participating in 6 diverse national championship events during the season (2004-2005).

A total of 1139 bouts involving 1019 athletes occurred during the study period. Overall, 186 injuries were recorded with an injury per bout ratio of 0.163 [C.I. 95%: 0.142-0.184] and a ratio of 183 injuries per 1000 athletes [C.I. 95%: 159-205]. The demographic characteristics of the athletes (injured or non-injured) have been shown (Table 1).

Results indicated that experienced competitors (more than 3 y) were more injury- prone than less experienced ones (P= 0.002). No significant differences between injured and non- injured athletes regarding the variables such as age, weight and belt rank were found.

With regard to mechanism of injury, punches (90, 48.4%) caused more injuries than kicks (62, 33.3%). Other mechanisms such as stumble and blocking the opponent's strike accounted for the remaining 34 injuries (18.3%). The injuries were most commonly located in the head and neck followed by the lower limb, upper limb and trunk (Table 2). Figure 1 shows the distribution of injuries in a schematic karateka, as a summary.

The injuries primarily consisted of muscle strain and contusion (81, 43.6%), hematoma and epistaxis (49, 26.3%), lacerations and abrasions (28, 15.1%), concussion (13, 7%), tooth avulsion or subluxation (3, 1.6%), joint dislocation (3, 1.6%) and fractures (3, 1.6%) (Table 3). Among concussions, only one injured athlete presented with complete loss of consciousness and transferred to hospital by medical emergency. The majority of the injuries were grade 1, in which athlete was able to continue the competition after a short time of rest or medical care (149, 80.1%). Grade 2 and 3 injuries constitute the remaining cases; 27 (14.5%) and 10 (5.4%) respectively and athlete withdrew from the competition or transferred to the hospital. With regards to the score of the bout at the time of injury, the injured athletes were in the winning (99, 53.2%), loss (75, 40.4%) and draw positions (12, 6.4%). There was no statistical association between the injury rate and score at the time of injury. With regard to the time of injury during the bout, each match was divided to 3 sections: first 30 seconds, middle 60 seconds and last 30 seconds. 48 (25.8%), 96(51.6%) and 42 (22.6%) injuries were recorded in these sections; respectively.

Several studies are comparable to our investigation, principally studies directed towards examining injuries sustained while competing (Birrer and Halbrook, 1988; Buschbacher and Shay, 1999; Johannsen and Noerregaard, 1988; Kujala et al., 1995; MacLatchie, 1981; Stricevic et al., 1983; Tenvergert et al., 1992; Tuominen, 1995; Zetaruk et al., 2000a). The rate of injuries in our study, 0.16 injuries per bout, a figure that is lower than those previously reported by Arriaza and Leyes, 2005 (0.31), Tuominen et al. (1995) (0.28), Johannsen and Noeregaard (1988) (0.26), Stricevic et al., 1983 (0.30) and more than Critchley (1999) (0.09) and compares favorably with Zetaruk et al., 2005 (17%) and McLatchie, 1977 (0.20). This may be due to the different level or style of competitions (sparring vs. non-contact) in these studies. Injury rates from martial arts tournaments which are not of the light contact form tend to be much higher. For example, McLatchie, 1977 found a far higher rate of 53/100 but studied only participants in aggressive full-contact knock-down championships.

Although martial arts have a reputation for being a high risk sport, many authors do not support this belief. Tenvergert et al., 1992 studied injuries associated with four sports over a 7-year period. The annual injury rates in martial arts were lower than soccer, volleyball and gymnastics. The injury pattern in our study compares relatively to earlier studies (Arriaza and Leyes, 2005; Birrer 1988; 1996; Critchley et al., 1999; Muller-Rath et al., 2000; Stricevic et al., 1983; Tuominen, 1995; Zetaruk et al 2000a) in which hematomas, contusions and strains have been reported as the most frequent injuries.

Muscle strains and contusions were the most frequent types of injury in our study (43.6%). These lesions are often due the result of ballistic movements such as kicking, particularly if there has not been an adequate warm-up. The coaches clearly have a key role to insist on proper and full warm-up routines. We also found a high incidence of hemorrhage (49, 26.3%) or once in every 23 bouts which is lower than one in every ten matches reported by Arriaza and Leyes, 2005. This high incidence represents the risk of blood-borne pathogen transmission. Therefore, special cautions should be applied by attending physicians to minimize the risk.

The nose is the most common site of hematomas. Other common hematoma sites are the forearm, which is widely used for the blocks, and the dorsum of the foot, which is exposed during kicks and blocks. In our study, we recorded 3 dental avulsions (1.6%), which corresponds well with Arriaza and Leyes, 2005 who reported dental avulsions and teeth fractures in 1.4% of injuries. These figures have reported to be higher in previous tournaments (Kujala et al., 1995). Since 1994, the use of mouth-guards is compulsory in karate competitions and it has decreased the incidence and severity of dental injuries.

One of the most clinically important findings of this study is the higher rate of concussion (13, 7%) when compared with the studies conducted by McLatchie et al (1977) (3%), Buschbacher (1999) (3%) and Arriaza and Leyes, 2005 (3.8%). It may be partly explained by the fact that the Iranian coaches promote the use of high kick techniques in athletes, because they regard these techniques as aesthetical ones with resultant full scores. As a result, if the athlete performs the techniques properly, there will be a considerable risk for the opponent to be injured by a heavy strike. On the other hand, because of the less controllable and risky nature of these kicks, the athlete may fall on her back and injured herself as head trauma and concussion. Nevertheless, the complete loss of consciousness was reported only in one competitor, who on being transported to hospital and discharged one day later, with no apparent consequence. As concussion may be a serious and potentially fatal injury, it seems that a particular emphasis should be placed on education and control by competitors and referees to reduce the contact to the head and neck region in Shotokan karate.

With regard to the localization of injuries, head and face represent the highest percentage of injuries (55.4%), although the relative frequency is lower than what reported by some authors such as Arriaza and Leyes, 2005 (84.1%) and Tuominen, 1995 (97%).

In our study, lower limb injuries (21% of all injuries) were more frequent than some other studies by Arriaza and Leyes, 2005, Johannsen and Noerregaard (1988) and MacLatchie (1977) who report lower frequencies; 6.4%, 4% and 9%, respectively. It may be explained by the new changes in scoring rules, which reward leg techniques more than before and therefore make them more popular among athletes. Leg injuries mostly occur during contact of the instep or shin with the opponent's elbow, hip, or forearm. The leg is also often injured when both opponents perform a leg maneuver at the same time.

Concerning injury severity, the rate of severe injury (grade 3) was 8.8 per 1000 bouts (9.8 per 1000 athletes). This rate is lower than the ones reported in other sports such as tae-kwondo (23-33.5), soccer (16.6-23.1), amateur boxing (47.5) (Kujala et al., 1995; Plancher and Minnich, 1996), aikido (28%) and kung fu (18%) (Zetaruk et al., 2005). However, the definition and classification of severity may differ between studies and therefore making meaningful comparisons is difficult.

With regard to mechanism of injury, punches were associated with more injuries (48.4%) than kicks (33.3%). Other mechanisms such as stumble and blocking the opponent's strike accounted for the remaining 18.3%. At the first glance, it seems that punches have a higher injury ratio than kicks (around 1.5 to 1), but as the number of punches in a karate contest is much higher than the number of kicks (with a ratio of approximately 10 to 1), the inverse conclusion would be more reasonable.

We found that injuries were more common among experienced athletes and the risk of injury increases with number of years of training. It is not surprising that such a relationship exists when one considers that speed, force of techniques, and confidence all increase with experience. This potentially leads to more aggressive style, placing the more experienced karateka at increased risk of injury.

With regard to the time of injury during the bout, although we expected to record more injuries in the last 30 seconds of the bout, due to maximal tension and stress as well as fatigue in this time, no significant difference was found. Furthermore, there was no statistical correlation between the occurrence of injury and score at the time of injury. Because these topics have been first proposed as potential risk factors in this study, it should be addressed in future studies to compare the results.

Our results support that the attendance of a qualified physician in a karate competition is essential. In our study, interventions were called up approximately in one in every 6 matches. However, some of these requests for medical interventions are not for real injury. Several factors have been recognized for injury prevention. The most important factors in decreasing the injury rate has been the enthusiasm of the referees to stop play that is dangerously violent, and penalize competitors who participate without proper regard for safety. It is proposed that the outlawing of particular uncontrollable methods of attack and having referees apply the already existing rules for competition strictly would reduce injury risk to athletes. Furthermore, attendance of medical personnel is a necessity, not only to manage injuries but also identify predisposing factors to the injury. In addition, we argue that injury risk would reduced by factor including a) careful teaching, and b) close monitoring by coaches to ensure faultless control of each strike. Routine warm-up exercises before each session, the use of protective pads and gear and padded flooring may also have preventive roles. Provided these guidelines are followed, Shotokan karate would be a suitable and low risk sport for female participants.

There were some limitations to our prospective study. First, it was very difficult for us to identify the precise duration of the matches: each karate bout lasts 2 min in competitions for females, but some may finish before time due to disqualification, severe injury or scoring full points, and others may have gone on to an extra time to decide the winner if two athletes draw at the end of the usual time. Therefore, we could not carry out an accurate calculation of the injury rate per minute of exposure. However, the statistical data of the number of injuries per 1,000 bouts (athlete exposures) and per 1,000 athletes permits us to compare karate statistics with other sports disciplines.

Other limitations of the study relate to our definition of injury. Because we define injury based on the request of competitor or referee for medical intervention, we may incorrectly consider injury in an athlete who may simulate in an attempt to achieve time for recuperation or cause the score penalty of the opponent by referee. On the other side, we may overlook injuries in athletes who do not seek medical intervention due to their excessive motivation to terminate the bouts. A further drawback was the difficulty of knowing the exact severity of some injuries that could only be determined after comprehensive examination once the athlete returns home.

• 186 injuries were recorded during women competitions.
• Incidence rates of 0.163 injury per bout and 183 injuries per 1000 athletes were calculated.
• The injuries were most commonly located in the head and neck.
• Muscle strain and contusion, hematoma and epistaxis constitute the majority of injuries.