Journal of Preventive Medicine

Introduction
Jiu-Jitsu is a Japanese martial art that can be used in an offensive or defensive manner, and a system of close combat with an armed or unarmed opponent, and is known as an unarmed fighting style. It uses grappling techniques and the application of pressure on the joints. Almost all martial arts are related to Jiu-Jitsu, but some of them are heavily influenced such as Brazilian Jiu-Jitsu and Judo. Knowing the injuries and their main causes is the most important step to eliminate them. Due to scant research in the field of injury in Jiu-Jitsu sports in Iran, this study aims to investigate the prevalence, mechanism, type, time, and severity of injuries in Iranian Jiu-Jitsu athletes.

Methods
This is a descriptive and retrospective study. The study population consists of all elite male Jiu-Jitsu athletes in Iran in 2020, of whom 200 voluntarily participated in this research. Of these, 168 athletes over 18 years who had completed the injury report form were selected as the study sample. Their mean age was 27.69±6.04 years, and they had at least three years of experience in Jiu-Jitsu at the national level. Unwillingness to participate in the study, withdrawing from the study, and not having the presence of mind to remember the injuries experienced in the past were the exclusion criteria. The participants signed a consent form to participate in the research before starting the research. Then, their personal information was surveyed, and they were asked to write all the injuries they experienced during competitions and training in the past year in a researcher-made injury report form. The study variables included injury incidence rate, injury type, injury mechanism, injury severity, different anatomical areas of injury, time of injury (during training or competitions), and style of jiu-jitsu. The chi-square test was used to examine the difference in multi-level variables, and the proportion test was used to check the difference in two-level nominal variables. All statistical calculations were performed in SPSS software, version 22 software. The significance level was set at 0.05.

Results
The mean age, height, weight, and body mass index of participants were 27.69±6.04 years, 178.27±9.58 cm, 77.68±6.87 kg, and 77.68±6.87 kg/m2. Out of 168 participants, 67(39.9%) reported no injury, and 101(60.1%) reported at least one injury in the past year. A total of 126 injuries occurred in these 101 athletes. The chi-square test results showed a significant difference among the athletes in terms of the type of injury, nature of injury (acute or chronic), mechanism of injury, severity of injury, anatomical areas of injury, and four general areas of injury in the body. The most common type of injury was dislocation/partial dislocation, while the least common type was brain injuries. Moreover, 65.1%(82) of cases were related to acute injuries and 34.9%(44 cases) were related to chronic injuries. The most common mechanism of injury was the maximum pressure on the joints (37.3%), while the least common mechanism was direct contact (6.34%). Mild injuries (4-7 injury days) were the most prevalent injuries (53.2%), while severe injuries (8.7%) were the least prevalent injuries. Most injuries were reported in the knee area (29.4%), while the lowest prevalence was related to hip injuries (1.6%). The most injuries were in the lower limb area (37.3%), while the least were in the head and neck area (7.1%).
The proportion test results showed a significant difference in terms of time of injury in total, time of injury during training, and time of injury during competitions. In this regard, 69% of injuries occurred during training and 31% during competitions. The most injuries occurred during training with the opponent (46.8%), and the least occurred during cooling down after training. The most injuries occurred at the end of the competition (49.2%) and the least at the beginning of the competition. There was a significant difference in the prevalence of injuries among athletes in the styles of Ne-waza (Brazilian jiu-jitsu), fighting, and self-defense (kata). In Nawaza style, injuries were more (62.7%) and less in kata (7.9%).

Discussion
In Iranian Jiu-Jitsu athletes, the most common mechanism of injury is the maximum pressure on the joint; the most common type of injury is dislocation/partial dislocation, and the least common type is brain injury; the injuries are mostly mild or moderate; most of the injuries occur in the knee and shoulder joints; the prevalence of injuries is higher during training than during competitions, and those in Brazilian jiu-jitsu style report more injuries. According to these results, planning to prevent injury in these athletes is necessary.

Ethical Considerations
Compliance with ethical guidelines
All ethical principles were considered in this study. Informed consent was obtained from all participants.

Funding
This article was extracted from the master's thesis of Ali Sistar registered by the Faculty of Sport Sciences and Health, University of Tehran.

Authors' contributions
Conceptualization and Investigation: Ali Sistar and Hooman Minoonejad; Methodology, writing original draft, review & editing, resources, and supervision: All authors.

Conflicts of interest
The authors declared no conflict of interest.

Acknowledgements
The authors would like to thank all the martial arts athletes participated in this study for their cooperation.

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