Epidemiology of injuries in junior karate athletes: incidence and patterns at the Iranian National Championships

Abstract

Background

The rise in youth karate competition participation correlates with elevated injury risk. This study investigated injury incidence and patterns among Iranian junior athletes at the 2023 National Karate Championships (Tehran, April–May 2023), the official selection event for the national team, considering differences by age, sex, weight, and bout characteristics.

Methods

A prospective cohort design was employed, analyzing data from 1391 athletes across 1544 bouts. Injury data were systematically collected by qualified medical personnel using standardized forms. Injury incidence rates (IIRs) were rigorously calculated per 1000 athlete-exposures (AEs) and per 1000 min of exposure (MEs) to account for varying exposure durations.

Results

A total of 527 injuries were recorded during the competition. The overall IIR was determined to be 18.94 per 1000 AEs and 9.02 per 1000 MEs. The face was identified as the most commonly injured anatomical site, accounting for 46% of all injuries, while contusions were the most frequent injury type, comprising 48%. Athletes in the Under-21 (U21) male category exhibited the highest injury rates. Furthermore, more than half (52%) of all recorded injuries occurred within the first minute of a bout, and losing athletes sustained a disproportionately high 59% of the total injuries.

Conclusion

In conclusion, this study identified a high injury incidence among Iranian junior karate athletes, with the face being the most commonly affected region and contusions the predominant injury type. Male and U21 athletes showed notably higher injury rates, particularly early in bouts and among those who lost. These findings highlight the need for targeted preventive strategies and serve as a national benchmark for future injury surveillance in youth karate.

Introduction

Karate is a globally recognized martial art and combat sport [1]. The International Olympic Committee (IOC) acknowledges the World Karate Federation (WKF) as the premier international governing body, representing approximately 100 million athletes across 199 member countries [2]. The sport was scheduled to make its debut appearance on the official Olympic Games program at Tokyo 2020, subsequently postponed to July–August 2021 [3]. Karate is fundamentally divided into two primary modalities: sparring (kumite) and forms (kata) [2]. Kumite competitions are further categorized into individual and team events. In individual contests, athletes of similar weight compete within specified weight divisions, whereas in team contests, athletes compete without weight category restrictions [2].

Within karate competitions, different categories exist for athletes under 18 years old (U18), comprising 7 categories for females and 10 for males. In the U21 category, both male and female competitors are divided into five distinct weight divisions. Each bout in the U18 categories (both cadet and junior) lasts 2 min of ‘clean time’, while bouts in the male and female U21 categories extend to 3 min [3]. These variations in the number of weight divisions and bout durations serve as critical factors that allowed the researchers to analyze their potential effect on injury incidence by examining different categories separately.

Increased participation in sports competitions is generally associated with a heightened possibility of injury. In karate, injuries are observed in both disciplines, but more variable injury patterns are frequently encountered in kumite, largely influenced by external factors [4].The popularity of competitive karate among both genders exposes participants to high injury risks due to the sport’s physical demands [5]. Studies conducted over past decades have investigated the rate and severity of injuries in karate matches. Researchers such as Augustovičová, and et al. have reported a relatively low time-loss injury incidence rate for top-level karate competitions [6]. Conversely, Rosso et al. found that senior athletes, particularly senior males, sustained significantly more injuries compared to younger and female senior competitors [4]. Arriaza et al. noted that the injury rate for cadet top-level karate competition in their prospective study was considerably lower than rates previously published for karate [7]. However, a significant research gap exists: most prior studies focused predominantly on specific age groups or did not conduct comparative analyses between them [7, 8]. This highlights the critical importance of identifying potential risk factors for injury to inform the development of effective injury prevention strategies and policies within karate. By explicitly addressing this gap, the current study aims to provide a more nuanced understanding of injury risk factors across different developmental stages and genders. This detailed breakdown is crucial for informing age- and sex-specific training modifications, protective equipment recommendations, and medical preparedness, moving beyond a “one-size-fits-all” approach to athlete safety in karate.

During the study period, two World Karate Federation (WKF) rules were in effect that directly influenced the competitive environment [9]: direct blows to the head were prohibited (registered head contact incurred a penalty), and face mask use was not mandatory for cadets and juniors (though was previously required) [10]. According to WKF scoring criteria, any valid technique must be appropriately controlled, with ‘correct distance’ defined as contact delivered within 5 cm of the face, head, or neck as a light ‘touch.’ These rules define the regulatory framework within which the observed injury patterns occurred.

However, they also note that these potential confounders, coupled with the observed small injury rate, might not allow for definitive conclusions regarding their precise impact. The very mention of these rules highlights their fundamental influence on the competitive environment and, by extension, injury patterns. The shift from compulsory face masks for juniors and the prohibition of head blows are direct interventions aimed at safety, suggesting that the observed injury patterns are not merely inherent to karate but are actively shaped by the regulatory framework. Future rule changes or equipment mandates could significantly alter these patterns, underscoring the dynamic relationship between sport governance and athlete safety. The specific aims of this study were threefold: 1) To determine the proportion and overall incidence rate of injuries; 2)To meticulously describe the patterns of injury in terms of both anatomical location and injury type; and 3)To comprehensively compare injury risks among male and female athletes across the U18 and U21 age categories, as well as across different weight divisions, match outcomes (win vs. loss), and specific time intervals within the bouts during the Iranian National Karate Championships. The researchers hypothesized that injury incidence would vary significantly across different age groups, sexes, weight categories, match outcomes (win vs. loss), and the specific time points within the bout at which injuries occurred.

Methods

Study design and population

This investigation employed a prospective cohort study design, allowing for the observation of injury events as they occurred during the competition. The study population comprised all male and female athletes who actively participated in individual kumite competitions at the 2023 Iranian National Karate Championships. This championship served as a critical component of the national team selection process. Athletes were systematically grouped into three distinct age categories: cadets (aged 14–15 years), juniors (aged 16–17 years), and Under-21 (U21; aged 18–20 years). The duration of each bout was standardized as 2 minutes of ‘clean time’ for U18 categories (both cadet and junior), and 3 minutes of ‘clean time’ for U21 competitors.

Weight categories

The specific weight categories for each age group and sex are comprehensively presented in Table 1. This table provides the essential demographic framework of the study population, detailing the specific competitive structure (age and weight divisions) under which the athletes competed. This context is crucial for understanding the environment in which injuries occurred. It directly supports the study’s aim to compare injury risks across different weight divisions and age groups, making the subsequent results and discussion sections more interpretable and robust.

Table 1.

Age and weight categories

Age Group (yrs)	Sex	Weight Categories (kg)
Cadet (14–15)	Male	–52, − 57, − 63, − 70, + 70
	Female	–47, − 54, + 54
Junior (16–17)	Male	–55, − 61, − 68, − 76, + 76
	Female	–48, − 53, − 59, + 59
U21 (18–20)	Male	–60, − 67, − 75, − 84, + 84
	Female	–50, − 55, − 61, − 68, + 68

Data collection procedures

All data collection instruments, including injury checklists and classification schemas, were applied according to internationally standardized protocols that have been established and validated through multiple peer-reviewed publications in English-language literature [6, 11]. The Persian application of these protocols in this study was performed by trained tournament medical personnel following comprehensive instruction from the IKF Medical Commission Chairman. Given the absence of published Persian-language specific validation studies for the complete injury surveillance instrument at the time of this study, the methodological rigor was ensured through: (a) standardized daily quality control reviews of all recorded data; (b) independent expert verification and coding of all injuries using the OSICS-10 classification system; and (c) systematic feedback from the IKF Medical Commission regarding all severe and potentially severe injuries. This multi-layered quality assurance approach is consistent with international sports injury surveillance best practices [12, 13].”

The collected data encompassed: gender, age, weight category, the specific injured body part, the type of injury, the severity of the injury (categorized as minor or time-loss), the precise time of injury within the bout, and whether the injury was sustained by the winner or loser of each match. All injuries were definitively diagnosed by official tournament sports medicine personnel. For each tatami (competition area), a dedicated medical team consisting of one doctor and one assistant was present. The official tournament sports medicine staff received comprehensive instruction from the Chairman of the Medical Commission of the Iranian Karate Federation (IKF) regarding injury recording procedures prior to the commencement of the championship. To ensure data quality and uniform injury classification, the recorded data were meticulously reviewed three times daily. In instances where injuries were assessed as severe or potentially severe (classified as time-loss injuries), affected athletes were promptly referred to a nearby hospital for additional diagnostic tests, and the IKF Medical Commission Chairman directly gathered feedback on the diagnoses. All recorded injuries were subsequently coded by a trained researcher using the Orchard Sports Injury Classification System, Version 10 (OSICS-10), the current internationally standardized classification system for sports injury epidemiology. OSICS-10 provides systematic coding across anatomical location, tissue type, and pathological classification, ensuring standardized injury characterization consistent with international surveillance frameworks [7, 12–14].

This multi-layered approach to data collection and verification, from initial recording by medical staff to daily quality checks and expert coding, significantly enhances the reliability and validity of the injury data, minimizing potential biases and errors in classification. This rigorous methodology lends strong credibility to the study’s findings, particularly regarding the accuracy of injury incidence rates, anatomical locations, and injury types, making the study a valuable benchmark for future research and for informing policy decisions by sports federations.

Operational definitions

Injuries sustained during all bouts were prospectively recorded in situ on checklists. In addition to providing immediate care for injured athletes, the medical teams were also responsible for meticulously recording all injuries that occurred during the competition. In this study, an ‘injury’ was defined as any physical damage, regardless of severity or subsequent time-loss, observed by the attending medical personnel during competition. This comprehensive approach is consistent with international consensus recommendations for injury surveillance frameworks in combat sports, which aim to capture the true burden of sport-related harm rather than only time-loss events.Injuries were broadly categorized as non-time-loss or time-loss. Injuries were classified as ‘non–time-loss’ if they did not prevent continued bout participation. Conversely, ‘time-loss’ injuries were specifically defined as those that prevented the athlete from completing the current bout and/or subsequent bouts, and from participating in any sport activities for a minimum of 1 day thereafter. For clarity and alignment with recent consensus, ambiguous sub-tier severity categories (e.g., minor/medium) that were not validated against established criteria were omitted from the final analysis, retaining only the main distinction: time-loss versus non–time-loss [12].

One athlete-exposure (AE) was operationally defined as one individual athlete participating in a bout where they are exposed to the possibility of being injured; consequently, for each bout, there are two AEs. One minute of exposure (ME) was defined as one minute of fighting per individual athlete in a bout. While face masks were no longer mandatory for juniors during the study period, voluntary usage was not systematically recorded. Anatomical location categorization and injury type classification (contusions, lacerations, fractures, sprains, dislocations, and ligament ruptures) are based on clinical diagnosis documented by tournament medical personnel and subsequently coded using the Orchard Sports Injury Classification System, Version 10 (OSICS-10), which provides standardized pathoanatomical coding for sports injuries [14].

Data analysis

Given that the duration of combats differed between U18 and U21 female and male divisions, injuries were rigorously analyzed considering both athlete-exposures (AEs) and minutes of exposure (MEs) to risk. Injury incidence rates (IIRs) per 1000 AEs and per 1000 min of exposure (MEs) were calculated utilizing standard epidemiological methods. Subgroups were compared by computing the rate ratio (RR) of two IIRs. 95% confidence intervals (95% CIs) were computed for all IIRs and RRs using standard formulae appropriate for Poisson rates. The 95% CIs for RRs were specifically used to determine whether two IIRs differed significantly from one another; that is, two IIRs were deemed statistically different if the 95% CI for their RR did not encompass the null value. RRs with 95% CIs were calculated to compare injury incidence across subgroups (e.g., age, sex, weight). This dual exposure metric allows for a more nuanced and accurate comparison of injury rates, especially when comparing groups with different bout durations. It demonstrates a sophisticated understanding of epidemiological principles and strengthens the internal validity of the comparisons, making the findings more reliable for informing targeted interventions for specific age/sex groups.

Confidentiality and ethics approval

Prior to entering the championships, all participating athletes or their legal representatives provided written informed consent to allow for injury registration and treatment. The rules stipulated by the WKF mandate that before athletes are permitted to enter a championship, they must be declared fit to compete by their local medical authorities, and a corresponding medical certification must be issued. In this context, it is presumed that most, if not all, injuries reported to the tournament doctors would be acute in nature. All authors strictly adhered to the principles of the Helsinki Declaration and the ethical guidelines set forth by the Ethics Committee at the University of Hormozgan (approval number 1404.283). To guarantee athlete anonymity, injuries were recorded without any personal information that could facilitate identification of the athletes.

Result

Overall injury incidence rates

A total of 1391 athletes participated in 1544 bouts, during which 527 injuries were recorded. This yielded an overall injury incidence rate (IIR) of 18.94 injuries per 1000 athlete-exposures (AEs) (95% CI 17.36 to 20.63) and 9.02 injuries per 1000 min of exposure (MEs) (95% CI 8.25 to 9.81). For time-loss injuries, the incidence rate was 0.75 per 1000 AEs (95% CI 0.47 to 1.15) and 0.36 per 1000 MEs (95% CI 0.22 to 0.55). Table 2 provides a detailed breakdown of these rates by age group and sex. This table is the central data presentation for the study’s primary outcomes, allowing for direct, granular comparisons of injury incidence rates across all defined age and sex subgroups, which is a core objective of the research. The inclusion of both AEs and MEs, along with 95% CIs, provides a robust and statistically sound basis for understanding exposure-adjusted injury risk across varying bout durations, making the data highly interpretable and comparable to other epidemiological studies.

Table 2.

Number of athletes, bouts and injuries by age group and sex, including injury incidence rates (IIRs) per 1000 athletes of exposure (AEs) and 1000 min of exposure (MEs) with 95% CIs

	Female				Male
	cadet	junior	Under 21	Female total	Cadets	Juniors	Under 21	Male total	TOTAL
Number of athletes	291	211	145	647	292	264	188	744	1391
Number of bouts	311	231	168	710	323	299	212	834	1544
Number of athlete-exposure	582	422	290	1294	584	528	376	1488	2782
Number of minute-exposure	1164	844	870	2878	1168	1056	752	2976	5854
Number of injuries	49	66	83	198	120	103	106	329	527
Number of time-loss injuries	2	1	4	7	2	8	4	14	21
Injuries in total
IIR per 1000 athlete-exposures	8.42 (6.22–11.13)	15.64 (12.10–19.90)	28.62 (22.80-35.48)	15.30 (13.24–17.59)	20.55 (17.04–24.57)	19.51 (15.92–23.66)	28.19 (23.08–34.10)	22.11 (19.79–24.63)	18.94 (17.36–20.63)
IIR per 1000 min-exposures	4.21 (3.11–5.57)	7.82 (6.05–9.95)	9.54 (7.80-11.82)	6.88 (5.95–7.91)	10.27 (8.52–12.29)	9.75 (7.96–11.82)	14.10 (11.54–17.05)	11.06 (9.89–12.32)	9.02 (8.25–9.81)
Time-loss injuries
IIR per 1000 athlete-exposures	0.34 (0.04–1.24)	0.24 (0.01–1.32)	1.38 (0.38–3.53)	0.54 (0.22–1.12)	0.34 (0.04–1.24)	1.52 (0.65–2.99)	1.06 (0.29–2.72)	0.94 (0.51–1.58)	0.75 (0.47–1.15)
IIR per 1000 min-exposures	0.17 (0,02-0.62)	0.12 (0.01–0.66)	0.46 (0.13–1.18)	0.24 (0.09–0.50)	0.17 (0.02–0.62)	0.76 (0.32–1.50)	0.53 (0.14–1.36)	0.47 (0.26–0.79)	0.36 (0.22–0.55)

Injury pattern

Tables 3, 4, 5 and 6 provide an overview of the frequency and proportion of injuries by anatomical location, injury type, time of injury, and bout outcome, respectively.

Table 3.

Frequency and proportion (%) of injuries by anatomic location^*

		Female				Male
		cadet	junior	Under 21	Total female	Cadets	Juniors	Under 21	Total male	TOTAL
Anatomic location	Face	26(53)	35(53)	45(54)	106(53)	50(42)	43(42)	44(41)	137(42)	243(46)
	Head	1(2)	2(3)	6(7)	9(5)	11(9)	6(6)	10(9)	27(8)	36(7)
	Neck	1(2)	2(3)	3(4)	6(3)	4(3)	5(5)	1(1)	10(3)	16(3)
	Throat	10(21)	13(20)	10(12)	33(17)	16(13)	17(16)	16(15)	49(15)	82(16)
	Abdomen	0(0)	0(0)	0(0)	0(0)	0(0)	0(0)	0(0)	0(0)	0(0)
	Genitals	3(6)	2(3)	2(2)	7(3)	8(7)	5(5)	8(8)	21(6)	28(5)
	Upper Extremities	3(6)	10(15)	9(11)	22(11)	20(17)	19(18)	21(20)	60(18)	82(16)
	Lower Extremities	5(10)	2(3)	8(10)	15(8)	11(9)	8(8)	6(6)	25(8)	40(7)
	Total	49(100)	66(100)	83(100)	198(100)	120(100)	103(100)	106(100)	329(100)	527(100)

^*Data are shown as n(%)

Table 4.

Frequency and proportion (%) of injuries by type of injury^*

		Female				Male
		cadet	junior	Under 21	Total female	Cadets	Juniors	Under 21	Total male	TOTAL
Type of Injury	lacerations	11(22)	17(26)	17(20)	45(23)	21(17)	12(12)	13(12)	46(14)	91(17)
	Fractures	2(4)	1(1)	3(4)	6(3)	1(1)	1(1)	4(4)	6(2)	12(2)
	concussions	0(0)	0(0)	0(0)	0(0)	0(0)	0(0)	0(0)	0(0)	0(0)
	Sprains	0(0)	0(0)	1(1)	1(1)	1(1)	4(4)	2(2)	7(2)	8(2)
	Dislocations	0(0)	0(0)	0(0)	0(0)	2(2)	5(5)	0(0)	7(2)	7(1)
	Ligament Ruptures	0(0)	0(0)	0(0)	0(0)	0(0)	0(0)	1(1)	1(0)	1(0)
	contusions	15(31)	25(38)	20(24)	60(30)	73(61)	51(49)	69(65)	193(59)	253(48)
	swelling/Abrasion	21(43)	23(35)	42(51)	86(43)	22(18)	30(29)	17(16)	69(21)	155(30)
	Total	49(100)	66(100)	83(100)	198(100)	120(100)	103(100)	106(100)	329(100)	527(100)

^*Data are shown as n(%)

Table 5.

Frequency and proportion (%) of injuries by time of Injury^*

		Female				Male
		cadet	junior	Under 21	Total female	Cadets	Juniors	Under 21	Total male	TOTAL
Time of Injury	0–60	28(57)	30(45)	25(30)	83(42)	71(59)	71(69)	51(48)	193(59)	276(52)
	61–120	21(43)	36(55)	32(39)	89(45)	49(41)	32(31)	38(36)	119(36)	208(40)
	121–180			26(31)	26(13)			17(16)	17(5)	43(8)
	Total	49(100)	66(100)	83(100)	198(100)	120(100)	103(100)	106(100)	329(100)	527(100)

^*Data are shown as n(%)

Table 6.

Frequency and proportion (%) of injuries by bout Outcome ^*

		Female				Male
		cadet	junior	Under 21	Total female	Cadets	Juniors	Under 21	Total male	TOTAL
Bout Outcome	Win	15(31)	24(36)	31(37)	70(35)	47(39)	41(40)	60(57)	148(45)	218(41)
	Lose	34(69)	42(64)	52(63)	128(65)	73(61)	62(60)	46(43)	181(55)	309(59)
	Total	49(100)	66(100)	83(100)	198(100)	120(100)	103(100)	106(100)	329(100)	527(100)

^*Data are shown as n(%)

Anatomical location

The face was the most commonly injured anatomical location, accounting for 46% of all injuries. This was followed by the throat and upper extremities, each accounting for 16% of injuries. Other locations included the head (7%), neck (3%), genitals (5%), and lower extremities (7%). No injuries were reported in the abdomen. The data clearly shows the face as the most injured site and contusions as the most common injury type. Table 3 provides a detailed breakdown of injury locations.

Type of injury

Contusions represented the most frequent type of injury (48%), followed by swelling/abrasions (30%) and lacerations (17%). Notably, no concussions were recorded. Table 4 provides a detailed breakdown of injury types.

Time of injury

Most injuries (52%) occurred within the first minute (0–60 s) of bouts. Table 5 illustrates the temporal distribution of injuries. This table presents novel data on the temporal distribution of injuries within a bout, which the authors identify as a strength.

Result of the bout

Injuries occurred more frequently in losing athletes, who sustained 59% of the total injuries, suggesting higher vulnerability or increased risk-taking under competitive pressure. Table 6 details injuries based on bout outcome. This table also contributes novel data by linking injury occurrence to bout outcome.

Injury risk factors

Sex

Male athletes consistently exhibited a higher rate of injuries compared to female athletes. The overall IIR for males was 22.11 per 1000 AEs (95% CI 19.79–24.63) and 11.06 per 1000 MEs (95% CI 9.89–12.32). For females, the overall IIR was 15.30 per 1000 AEs (95% CI 13.24–17.59) and 6.88 per 1000 MEs (95% CI 5.95–7.91). U21 males exhibited the highest rates, significantly exceeding cadets (RR: 3.4, 95% CI: 2.7–4.3).

Age group

The injury rate in both sexes was significantly higher in the U21 group compared to the cadet and junior groups. Table 7 illustrates female athletes, the relative risk per 1000 AEs in U21 was 28.62 (95% CI 22.80-35.48), compared to 8.42 (95% CI 6.22–11.13) in cadets and 15.64 (95% CI 12.10–19.90) in juniors. Similarly, for male athletes, the relative risk per 1000 AEs in U21 was 28.19 (95% CI 23.08–34.10), compared to 20.55 (95% CI 17.04–24.57) in cadets and 19.51 (95% CI 15.92–23.66) in juniors. The corresponding relative risks per 1000 MEs also showed similar trends, with U21 males having the highest relative risk (14.10; 95% CI 11.54–17.05). The U21 male group had the highest injury rates, and the injury rate in both sexes was higher in the U21 group compared with that in the cadet and junior groups. This pattern is statistically significant. The U21 category also has longer bout durations (3 min vs. 2 min for U18).

Table 7.

Injury incidence rates (per 1000 AEs) by age group and sex

Age Group	Male IIR	Female IIR
Cadet	20.55	8.42
Junior	19.51	15.64
U21	28.19	28.62

Weight categories

Among male athletes, the weight categories with the highest injury incidence were − 84 kg (U21), -63 kg (cadet), and − 70 kg (cadet). Athletes in heavier weight categories (e.g., U21 male − 84 kg) had a 1.5-fold higher injury rate compared to lighter divisions (RR: 1.52, 95% CI: 1.12–2.07).

Comparative analyses revealed significantly higher injury rates in U21 males vs. cadets (RR: 1.37, 95% CI: 1.07–1.76), males vs. females (RR: 1.45, 95% CI: 1.18–1.77), and during the first minute of bouts vs. remaining time (RR: 4.40, 95% CI: 3.71–5.21). Losing athletes had a 1.43-fold higher injury risk than winners (95% CI: 1.21–1.69).

Discussion

This prospective cohort study aimed to analyze injury incidence and patterns in junior-level Iranian karate athletes during a national championship, encompassing cadet (14–15 years), junior (16–17 years), and U21 (18–20 years) age groups. Across 1544 bouts and 1391 athletes, 527 injuries were recorded, with an overall injury incidence rate (IIR) of 18.94 per 1000 athlete-exposures (AEs) and 9.02 per 1000 min of exposure (MEs). Contusions were the most common injury type (48%), with the face being the most frequently injured anatomical site (46%). The U21 male group exhibited the highest injury rates, and 52% of all injuries occurred in the first minute of competition. A higher proportion of injuries (59%) occurred in losing athletes. These findings build on previous literature by providing detailed epidemiological patterns across age, sex, and performance outcomes in competitive youth karate, adding new insight into temporal injury dynamics and winner–loser injury relationships.

The injury incidence rates reported in this study are consistent with some and lower than others in the existing body of work. For instance, Arriaza et al. (2016) reported an IIR of 15 injuries per 1000 AEs in elite adolescent karate athletes, comparable to our findings in cadets and juniors [15]. However, our IIR is substantially lower than that found by Rosso et al. (2023) in European adults (45.3/1000 AEs) and by Lystad et al. (2020), who noted pooled Olympic-level injury rates of 88.3/1000 AEs and 39.2/1000 MEs [4, 9]. This disparity may reflect cultural differences in refereeing strictness, training intensity, and athlete maturity, as Iranian junior competitions emphasize technical control over aggressive engagement compared to European adult tournaments. In our study, participants were younger and subject to strict WKF guidelines prohibiting heavy head contact. Conversely, in adult competitions, higher-intensity techniques and more permissive contact rules may elevate injury risk. Additionally, regional differences in officiating standards and cultural tolerance for aggressive engagement could influence injury patterns.

Regarding sex-based differences, our results showed a significantly higher injury rate in male athletes (22.11/1000 AEs) compared to females (15.30/1000 AEs), which supports findings from Rosso et al. (2023) and Macan et al. (2006) who observed more frequent injuries in male competitors [4, 12]. In contrast, Čierna and Lystad (2017) found no statistically significant sex difference in injury incidence among youth athletes [16]. These contrasting results may be explained by biological and tactical variables: male participants consistently demonstrated higher injury rates, corroborated by meta-analyses that attribute this gap to greater lean body mass and higher striking force, contributing to greater mechanical loads upon contact [17, 18]. Furthermore, male athletes may demonstrate more risk-oriented strategies, including faster tempo and greater aggression, which could amplify injury risk [19]. Differences in skill levels, reaction speed, and competition density between male and female divisions may also account for variability.A key finding in this study was the elevated injury incidence in the U21 category, especially among males. This aligns with Kujala et al. (1995) and Zetaruk et al. (2000), who observed higher injury rates in late adolescent and young adult athletes compared to children [20, 21]. Our findings also concur with recent multi-sport analyses: injury rates rise with age and competitive tier as athletes mature physically and intensify participation. The longer bout duration for U21 (3 min vs. 2 min for U18) increases exposure time and physical fatigue, which could impair neuromuscular control and elevate injury risk. Moreover, the elevated injury incidence in U21 athletes aligns with research indicating increased risk as athletes reach peak physical power, compete with greater force, and accumulate more cumulative bout exposure. These transitional biological and developmental changes, alongside intensified bout durations, contribute to this vulnerability. Interestingly, some studies, such as those by Stricevic et al. (1983) and McLatchie (1976), reported higher injury rates in younger competitors, suggesting that inexperience may also be a critical risk factor [18, 22]. However, differences in training quality, tactical understanding, and competition format (e.g., elimination vs. league structure) may explain this divergence.

The predominance of facial injuries, despite regulatory constraints on head contact, was striking. Our findings are consistent with those of Critchley et al. (1999) and Arriaza and Leyes (2005), Rahimi et al. (2012) who reported that facial and cranial injuries accounted for more than 60% of all recorded trauma in karate [14, 23, 24]. This likely reflects the offensive targeting of high-scoring zones (head and upper body) under WKF rules. While the use of controlled contact is mandated, practical enforcement is often inconsistent, especially in the initial seconds of the bout when fighters rapidly engage. In contrast, studies such as Antekolović et al. (2016) and VencesBrito et al. (2016) found a higher prevalence of injuries to the extremities (hands, ankles), particularly in female and younger athletes [17, 25]. This discrepancy may arise from differing rule interpretations, protective equipment use, or fighting styles across regions. For instance, younger or female athletes may employ more defensive techniques, reducing head exposure while increasing limb use.

This study identified lower-extremity injuries in only 7% of all recorded injuries, which represents a notably lower proportion compared to several published karate epidemiology studies. Multiple factors contribute to the substantial variation in reported lower-extremity injury percentages across the karate literature, with percentages ranging from 6% to 41% across different populations and studies [4, 19].

Age and competitive level

Younger athletes in cadet and junior categories may preferentially employ defensive techniques with greater emphasis on upper-body contact zones, whereas older and more experienced senior athletes utilize high-amplitude kicks and sweep techniques that increase lower-extremity exposure and injury risk. This age-related tactical variation is reflected in the relative scarcity of lower-extremity injuries in the present junior-level cohort.

Sex-based tactical differences

Female competitors often demonstrate more technically conservative, positionally-grounded fighting strategies with reduced reliance on high-amplitude kicks, whereas male athletes frequently employ more aggressive upper-body striking patterns, resulting in different injury site distributions [4, 8].

Geographic and refereeing variations

Enforcement of WKF rules regarding controlled contact varies significantly between competitions. European tournaments with higher reported injury rates and more permissive contact enforcement show higher proportions of lower-extremity injuries compared to Asian tournaments emphasizing technical control [13, 24]. Similarly, strict refereeing that penalizes uncontrolled contact reduces injuries across all anatomical sites but may disproportionately protect the face through rule enforcement.

Rule interpretations and protective equipment

Inconsistent application of WKF regulations, varying availability and standardization of protective equipment (shin guards, foot protectors), and regional differences in mandatory equipment use influence the distribution of injuries across anatomical sites. Studies conducted in regions with more rigorous enforcement of protective equipment regulations report different injury patterns.

Methodological variations

Fundamental differences in injury surveillance methodology contribute substantially to reported variation. Some studies employ comprehensive prospective surveillance with trained medical personnel (as in the present study), while others rely on retrospective questionnaires or self-reported injuries, potentially underestimating minor injuries. Varying definitions of time-loss injuries, different minimum thresholds for injury reporting (e.g., injuries requiring medical attention vs. all observed injuries), and inconsistent classification frameworks produce heterogeneous results across the literature [8].

Competitive intensity and population characteristics

Elite international athletes competing at World Championships represent a qualitatively different population from national-level and regional competitors. Higher-intensity international competition, greater athlete skill uniformity, and more selective refereeing standards produce distinct injury patterns compared to younger, developing athletes in national championships [4, 13].

These multiple overlapping factors—age, sex, geographic location, refereeing standards, rule enforcement intensity, protective equipment use, methodology, and competitive level—interact to produce substantial variation in reported lower-extremity injury proportions across the karate epidemiology literature. Future studies should explicitly document these contextual factors to facilitate valid comparison and meta-analytical synthesis of karate injury data across populations.“Our study also observed that 52% of injuries occurred in the first 60 seconds of bouts, a pattern not widely reported in previous karate literature. However, this trend aligns with findings in judo and taekwondo, where injury risk spikes during initial aggressive exchanges before fatigue sets in [25, 26]. The early-bout period often involves sudden explosive movements, increased adrenaline, and reduced tactical restraint—factors that can compromise control and increase collision likelihood. It is also possible that insufficient pre-bout warm-up or psychological readiness plays a role. Hrysomallis and Goodman (2001) emphasized the importance of neuromuscular preparation and posture alignment in reducing early-phase injuries, supporting the idea that targeted pre-match conditioning could mitigate this trend [26]. Based on the high frequency of first-minute injuries (52%), we recommend dynamic warm-up protocols targeting reaction time and neuromuscular control (e.g., agility drills paired with simulated sparring) to reduce early-bout risks. Additionally, the WKF should reconsider mandatory face masks for juniors, given that 46% of injuries affected the face.

Another novel observation in our study is the higher proportion of injuries in losing athletes (59%), a trend echoed in research by Augustovičová et al., who associated losing status with lower technical execution and diminished defensive responsiveness [6]. Losing competitors may also adopt riskier tactics or experience lapses in concentration due to psychological pressure. Interestingly, this pattern was reversed in U21 male winners, who demonstrated a higher injury burden than losers—a result not previously emphasized in the literature. One possible explanation is that winning U21 athletes are more physically and technically dominant, thus engaging in more aggressive or high-amplitude techniques, such as high kicks or sweeps, which inherently increase risk. Macan et al. (2006) and Rosso et al. (2023) reported similar dynamics, where injury correlated with offensive intensity rather than merely match outcome [4, 12]. This highlights the dual nature of performance and injury-technical superiority does not always equate to reduced risk, especially in high-stakes matches where intensity is maximal.

From a practical standpoint, the findings of this study underscore the need for multifactorial injury prevention strategies in youth karate. Given the high injury burden among U21 males, specialized interventions targeting strength, flexibility, fatigue resistance, and tactical efficiency should be implemented. Programs should incorporate dynamic warm-up routines, neuromuscular training, and scenario-based drills mimicking high-intensity match openings. Additionally, given the disproportionate frequency of facial injuries, the WKF should reconsider the reintroduction of mandatory face masks for junior divisions. This would be in line with approaches used in youth taekwondo and boxing, where headgear has demonstrably reduced injury rates [24]. Moreover, mental preparation techniques such as self-regulation, situational awareness, and cognitive control should be emphasized to help athletes manage pressure and make safer decisions during competition [25]. Lastly, continuous injury surveillance and injury mechanism analysis should be mandated across national competitions, which will allow for real-time adjustment of safety policies and coaching strategies. Although this study did not record specific injury mechanisms (e.g., high kicks vs. punches), the predominance of facial contusions (46%) suggests that strikes to high-scoring zones (head/upper body) are a primary driver of injuries. Qualitative analyses of bout footage could further elucidate whether injuries stem from offensive techniques (e.g., mawashi geri) or defensive failures (e.g., poor blocking).

The impact of the study

The results of this study offer valuable information that can inform physicians responsible for karate tournaments about the actual types and frequencies of injuries encountered during competition. It is crucial to consider that previous studies may have utilized different data gathering and analysis methods, and that various karate styles may employ distinct competition rules. Even within Olympic karate, competition rules continually evolve, and these changes can significantly impact injury risks. Additionally, differences in the evaluation of injury severity by various authors could contribute to discrepancies in reported data. It is important to recognize that seemingly minor changes in competition rules, such as simply altering weight categories, can have a substantial impact on athlete safety. Therefore, continuous, prospective recording of injuries is essential to identify such changes and enable appropriate responses.

Limitations

While this study provides robust data for Iranian athletes, regional differences in training intensity, refereeing strictness (e.g., European vs. Asian tournaments), and cultural norms around contact may limit direct generalizability. Future multi-national studies could clarify whether these patterns persist across diverse populations. Another acknowledged limitation is the potential for underreporting of injuries, as some injured athletes might not have sought medical attention or care, or referees might have failed to call on the doctor when an athlete was injured. However, the degree of injury underreporting is likely to be small because the scoring system stipulates that valid techniques should not cause harm or injury to the opponent, providing athletes with an incentive to disclose all injuries. Although the scoring system incentivized injury reporting, minor contusions or abrasions may have been underreported if athletes chose to continue fighting without medical intervention. Furthermore, referees are explicitly instructed to call on medical personnel when a potentially injurious incident occurs. Lastly, the study did not record specific injury mechanisms (e.g., technique, movement pattern, phase of attack/defense), which limits the ability to develop highly specific preventative recommendations.

A primary limitation is the absence of recorded concussions, despite 36 head and 243 face injuries being documented. This mirrors recent literature indicating low diagnosed concussion incidence in karate, which may stem from light contact rules. However, this is more likely a significant under-detection, as systematic neurocognitive assessment tools (e.g., SCAT5) were not utilized by on-site medical staff. Given that athlete reporting and awareness of concussion symptoms remain limited, consensus statements urge improved education and the routine use of standardized tools to address this diagnostic gap in combat sports.

Conclusions

The study recorded a total of 527 injuries across 1544 karate combats at the Iranian National Karate Championship, with 21 (3.98%) of these classified as time-loss injuries. The time-loss IIRAE was 0.75 (95% CI 0.47–1.15) and the IIRME was 0.36 (95% CI 0.22–0.55), which is consistent with previously reported time-loss IIRs in karate. This dual profile suggests that while the sport is generally safe from severe harm, there is still a high burden of minor injuries that can impact training continuity and athlete well-being. Prevention efforts should therefore focus on both reducing the frequency of minor injuries (e.g., through improved protective gear or stricter contact rules) and continuously monitoring for any shifts in the low but persistent severe injury rates.

The most frequently injured anatomical region was the face (46%), followed by the throat (16%) and the upper extremities (16%). The most common type of injury observed was contusion (48%), followed by swelling/abrasion (30%) and laceration (17%). Female athletes consistently exhibited a lower rate of injuries compared with male athletes. These comprehensive findings can serve as a valuable benchmark for future studies aimed at evaluating the impact of any subsequent rule changes or the effectiveness of new preventive measures implemented in karate. This empowers the Iranian Karate Federation and other governing bodies to adopt an evidence-based approach to athlete safety. Any future modifications to rules, training protocols, or equipment can be rigorously evaluated against this baseline data to determine their effectiveness in reducing injury risk, fostering a continuous improvement cycle for athlete welfare.

Authors’ contributions

Dusana Augustovicova3, Montassar Tabben5, Yaping Zhong1: Conceptualization, Methodology, Software. Reza Seyedi1,2, Dusana Augustovicova3, 4: Data curation, Writing – original draft preparation. Masoud Khorsandi6,7, Shaghayegh Sayyar7: Visualization, Investigation. Montassar Tabben5, Yaping Zhong1: Supervision. Yuan Lin8, Mohammad Ebrahim Marjani9: Software, Validation. Reza Seyedi1,2, Dusana Augustovicova3: Writing – review & editing.

Funding

This research did not receive any funding.

Data availability

The datasets generated and/or analyzed during the current study are not publicly available because they have not been deposited in a public repository, but are available from the corresponding author on reasonable request.

Declarations

Ethics approval and consent to participate

The study protocol was approved by the Ethics Committee of … at University of Hormozgan (Approval No. 120452018), a registered body under Iran’s Ministry of Health and Ministry of Science regulations. All procedures conformed to the ethical standards of the Declaration of Helsinki. All participants, or their legal guardians, provided written informed consent prior to their inclusion in the study. To ensure participant anonymity, injury data were collected and recorded without any personal.

Consent for publication

Consent for publication is not applicable as no identifiable data of individual participants are included in this manuscript.

Competing interests

The authors declare no competing interests.

Corresponding author

Seyed Reza Seyedi.