
==== Front
J Funct Morphol Kinesiol
J Funct Morphol Kinesiol
jfmk
Journal of Functional Morphology and Kinesiology
2411-5142
MDPI

10.3390/jfmk9030148
jfmk-09-00148
Article
1-Year Prevalence and Factors Related to Injuries and Illnesses in Japanese Judo Collegiate Athletes
https://orcid.org/0009-0004-3444-1389
Kinoda Akira Conceptualization Methodology Software Validation Formal analysis Investigation Resources Data curation Writing – original draft Writing – review & editing Visualization
https://orcid.org/0000-0002-0209-5862
Mącznik Aleksandra Conceptualization Writing – original draft Writing – review & editing
https://orcid.org/0000-0001-8940-2206
Kimura Takeshi Methodology Validation Resources Data curation
https://orcid.org/0000-0002-9363-2722
Muramoto Yuki Resources
https://orcid.org/0000-0001-5576-5789
Katsumata Yoshinori Supervision
Sato Kazuki Project administration Funding acquisition *
Hue Olivier Academic Editor
Van den Tillaar Roland Academic Editor
Institute for Integrated Sports Medicine, Keio University School of Medicine, 35 Shinanomachi Shinjuku-ku, Tokyo 160-8582, Japan; akirakiak@gmail.com (A.K.); alexmacznik@gmail.com (A.M.); takeshikimura4@gmail.com (T.K.); yukimuramoto1019@gmail.com (Y.M.); goodcentury21@gmail.com (Y.K.)
* Correspondence: kazuki@a5.keio.jp; Tel.: +81-3-3353-1211; Fax: +81-3-5363-3875
28 8 2024
9 2024
9 3 14808 7 2024
26 8 2024
26 8 2024
© 2024 by the authors.
2024
https://creativecommons.org/licenses/by/4.0/ Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).
Despite its rich history and widespread participation, the research surrounding injuries and illness in judo remains relatively limited compared to other sports. The primary aim of this research was to investigate injuries and illness within a previous year in Japanese collegiate judo athletes and analyze possible factors associated with these. This was a cross-sectional observational study using a web-based survey to collect data on the 1-year prevalence of injuries and illness. This study involved 564 judo athletes (67% males), aged between 18 and 25 years. Of these, 344 athletes (61%) reported one or more injuries within the previous year, and 49 reported illness (9%). The more judo experiences the athlete acquired, the less likely they were to sustain an injury (OR: 0.9; 95% CI: 0.56–1.10; p-value < 0.05) or illness (OR: 0.9; 95% CI: 0.81–1.00; p-value < 0.05). Support of an athletic trainer was associated with 1.7 times increased odds of sustaining an injury (95% CI: 1.19–2.49; p-value < 0.05). Athletes with obese BMI status (BMI > 30) had 3.1 times higher odds of becoming ill (95% CI: 1.41–6.95; p-value = 0.005), and athletes training more than 5 days per week had the odds of becoming ill increased by 5.1 times (95% CI: 1.11–23.21; p-value = 0.036). Judokas with fewer years of experience and with obese status should be targeted in efforts to prevent injury and illness. Moreover, the support of an athletic trainer and the impact of weekly training days should be targeted in research efforts.

judo
injuries
martial arts
epidemiology
risk factors
prevention
UNIVASThis study was funded by the UNIVAS was not involved in data analysis or manuscript writing.
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pmc1. Introduction

Originating from Japan in the late 19th century, judo has evolved into a globally recognized sport, featured prominently in international competitions such as the Olympic Games. While judo offers numerous benefits, it is not without its inherent risks [1]. Injuries are an unfortunate reality in any sport, and judo is no exception. The combination of intricate throwing techniques, joint locks, and immobilizations exposes athletes to a wide array of potential injury mechanisms. Additionally, judo is a sport contested in weight-specific classes, which adds to the complexities of managing athletes’ health through constant monitoring of the body weight and composition, and the potential of risky practices such as rapid weight loss just before the competition. These practices as well as the intimate proximity and inherent physical contact with opponents might increase the risk of illness among judokas.

Furthermore, the close-contact nature of judo, with its constantly evolving rules, necessitates ongoing research to address emerging injury and illness profiles. Injuries may influence athlete performance and longevity in sport and illnesses can determine athlete’s success, being crucial elements in optimal athlete development. Japanese judokas are regarded as some of the best in the world, and knowing their injury and illness profiles could be helpful in contextualizing that success. Understanding the prevalence, nature, and contributing factors of injuries and illness in judo is essential for the development of effective prevention strategies, as well as for optimizing performance and athlete well-being.

Despite its rich history and widespread participation, the research surrounding injuries in judo remains limited compared to other sports [2,3]. Available data are only irregular, resulting in none of the judokas’ populations being researched thoroughly. The available data span different nationalities, ages, and levels, from elite Brazilian [4] or club-level Mongolian youth [5] through French regional and national levels of all ages [3] to the international elite Olympic-level judokas [6,7,8,9,10]. Research in the collegiate population specifically is extremely scarce with only one study in Polish physical education students taking a judo class as a part of their curriculum [11]. Additionally, establishing whether more injuries happen to female or male judokas, or in training versus competition, could allow for immediate application of preventive strategies in athlete development at any stage.

Finally, the research on illnesses in judokas is limited with only three studies ever looking at this topic [6,9,10]. All three studies were carried out during the Olympics and only gave the total prevalence numbers without any details. The impact of the limited research on injury and illness prevalence in judo athletes is potentially disastrous with coaches and athletes basing their training and competition decisions on guesses.

The primary aim of this research was to investigate the injuries and illnesses within a previous year in Japanese collegiate judo athletes. Additionally, we aimed to analyze possible factors associated with higher odds of sustaining an injury or contracting an illness.

2. Materials and Methods

This was a cross-sectional observational study using a web-based retrospective survey to collect data on 1-year prevalence of injuries and illness in collegiate judo athletes. The study was designed and conducted in accordance with the Declaration of Helsinki [12] and reported according to the STROBE-SIIS consensus statement [13]. The Ethics Committee of Keio University approved this study (approval number: 20211158).

Collegiate judo athletes associated with Japan Association for University Athletics and Sport (UNIVAS) were eligible and recruited from June to October 2022. Informed consent was collected digitally before athletes could access the web-based survey. Data submitted by non-athletes were excluded from the analysis.

The survey was hosted on a specially designed website (https://enquete.cc/q/BC2XC8A8; accessed on 1 June 2022). The questions were adapted from the latest consensus document of the Japanese Society of Clinical Sports Medicine and the Japanese Society for Athletic Training [14] and adjusted to better fit the collegiate demographic.

The survey consisted of questions on athlete’s characteristics (age, sex, judo experience, competition level, practice days per week, number of tournaments in a season, hand and leg dominance, year at university, height, weight, body mass index (BMI), support from an athletic trainer–a person who takes care of the athletes on a day-to-day basis providing first aid, injury prevention, and management), injuries, and illnesses experienced within the previous year. For injuries, location, severity, type, time lost from training/competition, mechanism, and onset data were collected. Diagnosis, severity, time lost from training/competition, and onset data were collected for illnesses.

Injury was defined as any tissue damage or other derangement of normal physical function that occurred during sports participation [14]. Illness was defined as a complaint or disorder experienced by an athlete not related to injury [14]. The severity was derived from the time loss from training and competition as follows: minimal (0 days lost), mild (1 day–1 week lost), moderate (1 week–1 month lost), severe (1 month–6 months lost), and very severe (>6 months lost) [13,15].

The statistical software SPSS (IBM Corp, Armonk, NY, USA. Release 2021 version 28.0) was employed for conducting statistical analysis. Continuous data were summarized using mean and standard deviation. Discrete data were summarized by calculating counts and percentages. A p-value lower than 0.05 was deemed statistically significant. To determine the one-year period prevalence, the number of athletes who sustained injuries/fell ill was divided by the total number of athletes and multiplied by 100%. Differences in injury and illness characteristics, such as location, severity, type, onset, mechanism, and time lost between females and males, injured and uninjured, and athletes with illness and no illness were compared using the chi-square test (Pearson’s chi-square, Fisher’s exact test, or Fisher’s exact test with Monte Carlo estimates, as appropriate). To evaluate the factors associated with injury and illness occurrence, regression models incorporating participant demographics and sports participation were utilized. Logistic regression was employed to estimate odds ratios (ORs) with 95% confidence intervals for each outcome variable.

3. Results

3.1. Characteristics of Japanese Collegiate Judo Athletes

This study involved 564 judo athletes (67% males) aged between 18 and 25 years and with an average of 12 years of experience in the sport. The characteristics of the athletes are presented in Table 1. The athletes were mainly at a regional or national level, 84% competed between 1 and 5 times per season, and on average were training six days per week.

3.2. Injuries and Illnesses

Out of 564 athletes, 344 athletes (61%) reported 581 injuries within the previous year, 15 reported COVID-19, and 34 reported other illnesses (9%). The characteristics of injuries and illnesses are presented in Table 2.

The overwhelming majority of injuries involved limbs, specifically joints. Most of the injuries (86%) required some time off from training and competition. Males reported a higher proportion of head injuries, moderate injuries, recurrent injuries, injuries occurring in training, and due to the direct mechanism. Females reported a higher proportion of elbow and ACL injuries and new injuries. In terms of illness, the only difference in proportions between males and females was in severity, where males reported a higher proportion of mild illnesses than females.

COVID-19 was the most reported illness (31%), followed by digestive (27%) and skin issues (16%).

3.3. Differences between Injured and Uninjured Judo Athletes

Differences between injured and uninjured athletes in proportion to various characteristics are presented in Table 3.

Differences between injured and uninjured athletes were found in proportions of the year of study, and the presence or lack of support from an athletic trainer. No differences in sex, BMI, practice days per week, frequency, and level of competition were detected.

3.4. Differences in Characteristics of the Athletes (n = 564) Who Reported Illness or No Illness

Differences in characteristics’ proportions between athletes who became ill and did not become ill are presented in Table 4. Differences between athletes with illness and those without were found in BMI and competition level, but not in sex, year at university, BMI status, practice days per week, competition frequency, support, or health status.

3.5. Factors Related to Sustaining an Injury in Judo Athletes

An analysis of the factors related to sustaining an injury is presented in Table 5. Fewer years of experience in judo and support from an athletic trainer were the only factors related to increased odds of sustaining an injury.

3.6. Factors Related to Experiencing an Illness in Judo Athletes

The factors related to illness in judo athletes are presented in Table 6. Obese BMI status, fewer years of experience, and more than 5 practice days per week were associated with higher odds of falling ill in Japanese judo athletes. Factors such as age, sex, year at university, competition level, and frequency were not associated with illness.

4. Discussion

Years of judo experience and support from an athletic trainer were the factors influencing the odds of sustaining an injury and BMI status, years of judo experience, and practice days per week were the factors influencing the odds of contracting an illness in Japanese judo athletes. Having the support of an athletic trainer was associated with 1.7 times increased odds of sustaining an injury. Athletes with obese BMI status (BMI > 30) had 3.1 times higher odds, and athletes practicing judo more than five days per week had 5.1 times higher odds of becoming ill. The more experience the judo athletes acquired in the sport, the less likely they were to both sustain an injury or fall ill. Factors such as age, sex, year at the university, frequency of competition, and competition level did not influence the odds of injury or illness in this population.

4.1. Prevalence of Injuries and Illness

Among Japanese collegiate judo athletes, 61% had been injured and 9% had become ill within the previous year. The injury prevalence found in this study seems similar to the other studies reporting a 10-year prevalence of 64.8% for musculoskeletal injuries in Brazilian state-associated judokas [16], but higher than ‘current injury’ reported by 39% of Mongolian judo club athletes (aged 9–22) [5] and 13.5% of French judokas injured within three competitions [17], 10–15% during Olympic tournaments [6,7,9,10], and 1.1% injured in the 21-year-long study of judo competitions in France [3].

In general, we found that injury patterns are very similar in male and female judo athletes, as did other studies [18]. However, slight differences exist. For example, a higher proportion of male athletes experienced head injuries, injuries of moderate severity, in season, in training, and due to the direct mechanism when compared to their female counterparts. Females experienced a higher proportion of elbow and ACL injuries than males. Mild illness and in-season illness were experienced in a higher proportion by males than females.

Moreover, this study found 2.6 times more injuries reported in training than in the competition, with 60% of injuries being sustained to the lower limbs. Lower-limb injuries (44%) were also most common in the 4-year investigation of national-level Korean athletes [18]. However, a study on competition injuries in French judokas showed that most of the injuries were to the upper body [3], a similar result to the results in three consecutive Olympics [8]. Therefore, perhaps the injuries sustained during training versus during the competition vary and should be investigated separately in future studies.

The illness prevalence in this study (9%) is high compared to the three available studies in judo Olympians of 4.2% in London [6], almost 3% in Rio [9], and almost 4% in Tokyo [10]. However, our study investigated 1-year prevalence in judo training and competition, whereas the other studies looked only at the prevalence during a judo Olympic tournament. Due to the fact that the timeframe, athlete level, and exposure type differed, these results should be considered with caution and within their respective contexts.

Illness prevalence in other sports showed however similar prevalence to the one found in this study. During multiday competition events, 6.8% of ill athletes were reported at the IAAF 2009 [19] and 2011 events [20], 7.2% at the 2010 Olympics [21], 8.2% at the 2012 Youth Olympics [22], 8.9% at the 2014 Olympics [23], or 12.1% at the FIFA 2010 [24]. Moreover, another study investigating illness prevalence in female high school students found that only 7.2% of athletes became ill but as much as 27.6% of non-athletes reported illness [25]. The illness prevalence in this study is around the prevalence reported for other sports but higher than in judo-specific studies, warranting more research.

4.2. Factors Associated with Injury

Sports experience had an injury-protective effect on judo athletes surveyed in this study. Other studies have reported contrary results with age or experience being factors promoting injuries. More years of experience were associated with higher odds of sustaining both acute and overuse injuries in the Finnish population (various sports) [26]. In judo collegiate athletes, age was associated with higher odds ratios of injuries [11]. The athletes, however, were of recreational status and chose judo as their PE subject rather than being devoted specialists. In a 21-year-long surveillance study in French judokas, the ones who competed at the national level experienced more injuries (1.44%) than regional and district judokas (0.9%) [3]. Therefore, a possible explanation for the findings of this study would be that more experienced athletes had more time to train their bodies to adapt to training and competitions. Longer training time also could have allowed for the accumulation of technical practice necessary to counter the attacks of the opponents or master advanced techniques of safe falls, and therefore reduce the likelihood of sustaining an injury. As judo is a combat sport where the opponents are actively trying to cause physical harm to each other, experience in defense techniques is crucial. Other aspects influencing this outcome could include accumulated training load, fitness levels, and competition experience as suggested for combat sports in general [8].

Support of an athletic trainer was associated with higher odds of sustaining an injury in collegiate Japanese judo athletes. This finding contradicts other studies that reported athletic trainers reducing rates and recurrence of injuries and proving to be effective in recognizing concussions in the US high school population [27]. Support from athletic trainers was reported by the injured US collegiate athletes to foster belief in successful recovery, normalize the struggle of the rehabilitation process, and help set clear goals and expectations [28]. Moreover, athletic trainer services were suggested as a cost-effective healthcare modality in school and community-based sports [29,30].

The influence of athletic trainers on increased injury prevalence found in this study may be due to several aspects. Athletes who had access to an athletic trainer could have increased their training volume and/or intensity due to treatment or advice given. Also, treatment such as taping or fitting with braces could have kept athletes with minimal injuries in play/competition, perhaps causing more severe injury in the long run. On the other hand, athletic trainers could have kept the athletes longer in rehabilitation, thoroughly checking before allowing for a return to play, and therefore causing the reported injuries to appear more serious when compared to the injuries sustained by athletes without access to an athletic trainer. Finally, athletic trainers’ care and education could have allowed the athletes to report the injuries more accurately. Additional attention from athletic trainers could have made an athlete remember the injury better and ensure improved recall in the retrospective survey.

4.3. Factors Associated with Illness

Years of experience in judo have been shown to protect against illness in Japanese collegiate athletes. Similarly, one study showed that younger collegiate female students were more likely to contact COVID-19 [31]. This is an interesting finding as sports have been shown to expose athletes to multiple stressors with the potential to depress immunity and increase the risk of illness [32]. Our findings, however, indicate that as the athletes move into later years in the sport, they probably learn how to navigate these stressors better to mitigate the risks of falling ill [33,34,35].

Obese BMI status was associated with higher odds of contracting illness in judo athletes. Athletes carrying more fat tissue may be more susceptible to hormonal and immunological changes that predispose them to illness. The literature on BMI and illness in athletes is limited. However, one study [31] showed that athletes who contracted COVID-19 had higher BMI than the ones who had not. There are studies showing obese status as a protective factor against sports injury in Canadian adolescent athletes [36], and other studies looking at child, youth, and adolescent populations show an overall negative effect of high BMI on sports injuries ranging in an increase of odds from 1.4 to 3.9 [37]. Bringing all the findings together may mean that although obese BMI status is not a detrimental factor for a sports injury in children, it may become one later in their career. Children develop fast and periodically experience growth spurts. Having a reserve of fat tissue to secure energy supply during the development may have a positive effect. As the athletes mature, however, the requirements of carrying a heavier body may exceed benefits and predispose the athletes to injuries.

Practicing judo more than five days per week was associated with 5.1 times higher odds of becoming ill. This outcome could be related to the increased possibility of overtraining and/or under-recovery, which were both indicated as factors driving immunodepression [25]. Therefore, research into the impact of training load on illness in judo or sports in general is warranted.

4.4. Limitations

This study presents several limitations that need consideration. The retrospective design of data collection in this study could have introduced a retrieval bias, where athletes could not quite remember actual timeframes for their injury and/or illness. Athletes’ injuries or illnesses were self-reported which could increase the number of reported cases. Additionally, we asked for details for up to the three most serious injuries, which could have resulted in underreporting. However, considering the retrospective design of this study, asking about the three most serious injuries aimed at assuring high-quality data, as the athletes are more likely to remember the details of these injuries. Moreover, data collected on injury details were limited, and therefore no injuries could be proposed for specific injury risk reduction efforts. The sample of athletes included in this study was homogenous, consisting only of Japanese collegiate judo athletes. Therefore, the results obtained may not be generalizable to the global population or other age/sports groups.

5. Conclusions

Judo athletes who are less experienced and have the support of an athletic trainer have higher odds of sustaining an injury. Judokas with less experience, obese BMI status, and training more than five days per week have higher odds of contracting illness.

The findings of this study suggest that less experienced judokas should be targeted with injury and illness prevention strategies. The role of athletic trainers in support of judo athletes should be investigated more thoroughly for tangible recommendations. Athletes with obese BMI status may be more susceptible to contracting an illness and therefore preventive measures, specifically for respiratory and skin diseases, should be undertaken. Special attention should be given to the training load the judokas are undertaking, as these could influence their susceptibility to illness.

Ultimately, the findings of this research paper will contribute to a deeper understanding of injuries and illnesses related to judo participation, fostering a safer environment for judo practitioners of all levels. Through informed interventions, such as rule modifications, athlete education, and improved training protocols, we can strive to minimize the frequency and severity of injuries, thereby enhancing the overall experience and longevity of judo participants.

Acknowledgments

We would like to thank the MS&AD Insurance Group Holdings, Inc., for their support in conducting this study, as well as all the athletes who responded to the survey.

Author Contributions

Conceptualization, A.K. and A.M.; methodology, A.K. and T.K.; software, A.K.; validation, T.K. and A.K.; formal analysis, A.K.; investigation, A.K.; resources, A.K. and T.K.; data curation, A.K. and T.K.; writing—original draft preparation, A.M. and A.K.; writing—review and editing, A.K. and A.M.; visualization, A.K.; supervision, Y.K.; project administration, K.S.; funding acquisition, K.S. All authors have read and agreed to the published version of the manuscript.

Institutional Review Board Statement

The study was conducted in accordance with the Declaration of Helsinki and approved by the Ethics Committee of Keio University (approval number: 20211158, 20 April 2022).

Informed Consent Statement

Informed consent was obtained from all subjects involved in the study.

Data Availability Statement

All data from these studies are contained within this manuscript or are available from the corresponding author upon reasonable request.

Conflicts of Interest

This study was funded by the UNIVAS. UNIVAS had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript; or in the decision to publish the results.

jfmk-09-00148-t001_Table 1 Table 1 Characteristics of judo collegiate athletes (n = 564).

Characteristic	All
n = 564
100%	Males
n = 376
66.7%	Females
n = 183
32.4%	Sex Undisclosed
n = 5
0.5%	
Age, years; mean ± SD	19.8 ± 1.2	19.8 ± 1.2	19.9 ± 1.3	20.4 ± 1.1	
Year at university; n (%)					
    Year 1	183 (32.4)	122 (32.4)	61 (33.3)	0 (0)	
    Year 2	138 (24.5)	100 (26.6)	37 (20.2)	1 (20.0)	
    Year 3	142 (25.2)	89 (23.7)	50 (27.3)	3 (60.0)	
    Year 4+	101 (17.9)	65 (17.3)	35 (19.1)	1 (20.0)	
Height, cm; mean ± SD	167.7 ± 8.2	171.6 ± 6.1	159.5 ± 5.6	168.4 ± 9.7	
Weight, kg; mean ± SD	76.5 ± 18.8	82.8 ± 18.3	63.5 ± 11.7	73.5 ± 24.6	
BMI *, kg/m2; mean ± SD	27.0 ± 5.1	28.0 ± 5.3	24.9 ± 4.1	25.6 ± 6.8	
Judo experience, years; mean ± SD	12.2 ± 3.7	12.2 ± 3.7	12.3 ± 3.8	9.8 ± 1.3	
Competition level; n (%)					
    regional	248 (44.0)	188 (50.0)	57 (31.1)	3 (60.0)	
    national	301 (53.4)	183 (48.7)	116 (63.4)	2 (40.0)	
    international	15 (2.6)	5 (1.3)	10 (5.5)	0 (0)	
Practice days per week; mean ± SD	5.7 ± 0.9	5.7 ± 0.8	5.7 ± 1.0	5.0 ± 2.2	
Tournaments per season; n (%)					
    1–5 matches	473 (83.9)	316 (84.0)	152 (83.1)	5 (100.0)	
    6–10 matches	77 (13.7)	53 (14.1)	24 (13.1)	0 (0)	
    11–15 matches	10 (1.8)	4 (1.1)	6 (3.3)	0 (0)	
    >16 matches	4 (0.7)	3 (0.8)	1 (0.5)	0 (0)	
Hand dominance; n (%)					
    right	474 (84.0)	308 (81.9)	161 (88.0)	5 (100)	
    left	78 (13.8)	57 (15.2)	21 (11.5)	0 (0)	
    both	12 (2.1)	11 (2.9)	1 (0.5)	0 (0)	
Leg dominance; n (%)					
    right	458 (81.2)	302 (80.3)	153 (83.6)	3 (60.0)	
    left	98 (17.4)	68 (18.1)	2 (15.3)	2 (40.0)	
    both	7 (1.2)	6 (1.6)	1 (0.5)	0 (0)	
Reported health; n					
    injury	344	225	118	1	
    illness	49	31	18	0	
    none (no injury and no illness)	202	139	59	4	
    both (injury and illness)	31	19	12	0	
Injuries per year; n (%)					
    none	220 (39.0)	151 (40.2)	65 (35.5)	4 (80.0)	
    one	179 (31.7)	115 (30.6)	64 (35.0)	0 (0)	
    two	100 (17.7)	63 (16.8)	37 (20.2)	0 (0)	
    three or more	65 (11.5)	47 (12.5)	17 (9.3)	1 (20.0)	
Illness; n (%)					
    COVID-19	15 (30.6)	10 (32.3)	5 (27.8)	0	
    other illness	34 (69.4)	21 (67.7)	13 (72.2)	0	
Support *; n (%)					
    AT	165 (29.3)	112 (29.8)	51 (27.9)	2 (40.0)	
    Non-AT	399 (70.7)	264 (70.2)	132 (72.1)	3 (60.0)	
* BMI—body mass index; AT—had the support of an athletic trainer, Non-AT—had no support of an athletic trainer.

jfmk-09-00148-t002_Table 2 Table 2 Characteristics of injuries (n = 581) and illnesses (n = 49) in judo collegiate athletes (n = 564).

Characteristic	All	Males	Females	Difference in Proportions between Males and Females	Sex Undisclosed	
				[Pearson’s χ2]		
				p-value		
INJURY	581 *	388	190		3	
Location; n (%)						
    Head	23 (4.0)	20	3	0.039	0	
     head	14	12	2	0.134	0	
     face	9	8	1	0.206	0	
    Trunk	61 (10.5)	42	18	0.617	1	
     cervical spine	9	6	3	0.976	0	
     chest	10	7	3	0.845	0	
     upper back	5	5	0	0.116	0	
     abdomen	2	2	0	0.322	0	
     lumbo-sacral spine	30	21	9	0.731	0	
     buttock	4	1	3	0.072	0	
     groin	1	0	0	NA *	1	
    Upper limb	195 (33.6)	123	71	0.175	1	
     shoulder	71	50	21	0.528	0	
     upper arm	0	0	0	NA *	0	
     elbow	60	33	27	0.035	0	
     lower arm	1	1	0	0.484	0	
     wrist	18	9	8	0.206	1	
     hand	13	8	5	0.665	0	
     finger	29	20	9	0.829	0	
     thumb	3	2	1	0.987	0	
    Lower limb	302 (52.0)	203	98	0.867	1	
     hip joint	1	0	1	0.153	0	
     thigh	18	10	8	0.288	0	
     knee	121	88	33	0.140	0	
     ACL *	30	14	16	0.014	0	
     Achilles	0	0	0	NA*	0	
     lower leg	9	7	2	0.493	0	
     ankle	41	29	11	0.454	1	
     toe	35	20	15	0.195	0	
     fracture	47	35	12	0.264	0	
	Missing 14	Missing 12	Missing 2		Missing 0	
Time lost; n (%)						
    yes	500 (86.1)	339 (86.9)	161 (84.3)	0.142	2	
    no	81 (13.9)	51 (13.1)	30 (15.7)	0.142	1	
Severity; n						
    minimal (0 days lost)	77	45	32	0.795	1	
    mild (1 day–1 week lost)	115	73	42	0.396	1	
    moderate (1 week–1 month lost)	226	166	60	<0.001	0	
    severe (1 month–6 months lost)	124	83	41	0.084	1	
    very severe (>6 months lost)	39	23	16	0.911	0	
Type; n						
    new	407	272	135	<0.001	2	
    recurrent	158	109	49	0.010	0	
    overuse	16	9	7	0.768	1	
Onset (part of the season); n						
    pre-season	196	117	79	0.964	3	
    in season	327	238	89	<0.001	0	
    post-season	44	27	17	0.832	0	
    other	14	8	6	0.836	0	
Onset (competition or training); n						
    in competition	160	101	59	0.353	0	
    in training	421	289	132	<0.001	3	
Mechanism; n						
    direct	398	275	123	<0.001	3	
    indirect	118	72	46	0.780	0	
    non-contact	65	43	22	0.282	0	
ILLNESS	49	31	18			
Diagnosis, n						
    COVID-19	15	10	5	0.743	0	
    digestive issues	13	6	7	0.135	0	
    skin issues	8	5	3	0.961	0	
    heat stroke	5	4	1	0.413	0	
    hay fever	3	3	0	0.173	0	
    urological issues	3	3	0	0.173	0	
    gynecological issues	2	0	2	0.058	0	
Time lost; n						
    yes	47	30	17	0.691	0	
    no	2	1	1	0.691	0	
Severity; n						
    minimal (0 days lost)	2	1	1	NA *	0	
    mild (1 day–1 week lost)	10	8	2	0.016	0	
    moderate (1 week–1 month lost)	25	17	8	0.170	0	
    severe (1 month–6 months lost)	8	5	3	0.187	0	
    very severe (>6 months lost)	4	0	4	0.004	0	
Onset (part of the season); n						
    pre-season	13	6	7	0.612	0	
    in season	25	17	8	0.170	0	
    post-season	11	7	4	0.201	0	
* each athlete could report up to three injuries; ACL—anterior cruciate ligament; NA—not applicable.

jfmk-09-00148-t003_Table 3 Table 3 Differences between injured and uninjured judo athletes (n = 564).

Characteristic	Injured	Uninjured			
	n = 344	n = 220	χ2	p-Value	
Sex; n					
    male	225	151	4.677	0.096	
    female	118	65			
    undisclosed	1	4			
Year at university; n (%)					
    Year 1	85 (24.7)	98 (44.5)	24.563	<0.001	
    Year 2	91 (26.5)	47 (21.4)			
    Year 3	97 (28.2)	45 (20.5)			
    Year 4+	71 (20.6)	30 (13.6)			
BMI; n (%)					
    underweight + normal 18.5–24.9	152 (44.2)	94 (42.7)	1.660	0.436	
    overweight 25.0–29.9	123 (35.8)	72 (32.7)			
    obese > 30.0	69 (20.0)	54 (24.6)			
Competition level; n					
    regional	145	103	1.245	0.537	
    national	190	111			
    international	9	6			
Practice days per week; n					
    1	1	6	12.146	0.059	
    2	2	5			
    3	5	3			
    4	11	9			
    5	33	14			
    6	284	180			
    7	8	3			
Tournaments per season; n					
    1–5	284	189	2.604	0.626	
    6–10	49	28			
    11–15	8	2			
    16–20	2	1			
    21–25	0	0			
    26–30	1	0			
    >31	0	0			
Support *; n (%)					
    AT	113 (32.8)	52 (23.6)	5.502	0.023	
    Non-AT	231 (67.2)	168 (76.4)			
* AT—had the support of an athletic trainer, Non-AT—had no support of an athletic trainer.

jfmk-09-00148-t004_Table 4 Table 4 Differences in characteristics of the athletes (n = 564) who reported illness (n = 49) versus no illness (n = 515).

Characteristic	Illness	No Illness			
	n = 49	n = 515	χ2	p-Value	
Sex; n					
    male	31	345	0.873	0.646	
    female	18	165			
    undisclosed	0	5			
Year at university; n					
    Year 1	13	170	0.994	0.803	
    Year 2	14	124			
    Year 3	13	129			
    Year 4+	9	92			
BMI; n (%)					
    underweight BMI < 18.4 + Normal BMI 18.5–24.9	15 (6.1)	231 (93.9)	9.408	0.009	
    overweight BMI 25.0–29.9	15 (7.7)	180 (92.3)			
    obese BMI > 30.0	19 (15.4)	104 (84.6)			
Practice days per week; n					
    1	1	6	8.365	0.213	
    2	0	7			
    3	0	8			
    4	1	19			
    5	0	47			
    6	45	419			
    7	2	9			
Tournaments per season; n					
    1–5	41	432	0.418	0.981	
    6–10	7	70			
    11–15	1	9			
    16–20	0	3			
    21–25	0	0			
    26–30	0	1			
    >31	0	0			
Support *; n					
    AT	19	146	2.350	0.088	
    Non-AT	30	369			
Competition level; n (%)					
    regional	22 (8.9)	226 (91.1)	6.538	0.038	
    national	23 (7.6)	278 (92.4)			
    international	4 (26.7)	11 (73.3)			
Health status; n					
    injury	31	313	0.116	0.762	
    no-injury	18	202			
* AT—had the support of an athletic trainer, Non-AT—had no support of an athletic trainer.

jfmk-09-00148-t005_Table 5 Table 5 Factors related to sustaining an injury in judo athletes.

Factor	Odds Ratio	95% CI	p-Value	
Age	0.786	0.560–1.102	0.162	
Sex				
    male	reference			
    female	0.791	0.524–1.193	0.263	
Year at university				
    Year 1	reference			
    Year 2	0.579	0.320–1.048	0.071	
    Year 3	0.784	0.342–1.796	0.565	
    Year 4+	0.963	0.298–3.113	0.963	
Judo experience	0.913	0.560–1.102	<0.05	
BMI				
    normal + underweight < 25	reference			
    overweight 25.0–30.0	1.109	0.677–1.817	0.580	
    obese > 30.0	0.885	0.574–1.364	0.681	
Support *; n (%)				
    Non-AT	reference			
    AT	1.656	1.101–2.489	<0.05	
Competition level				
    regional	reference			
    national	1.196	0.843–1.695	0.315	
    international	0.943	0.317–2.802	0.916	
Practice days per week				
    1–5	reference			
    6–7	0.902	0.548–1.483	0.684	
Tournaments per season;				
    1–5 matches	reference			
    >6 matches	1.078	0.638–1.821	0.779	
* AT—had the support of an athletic trainer, Non-AT—had no support of an athletic trainer.

jfmk-09-00148-t006_Table 6 Table 6 Factors related to illness in judo athletes.

Factor	Odds Ratio	95% CI	p-Value	
Age	0.604	0.337–1.083	0.091	
Sex				
    male	reference			
    female	1.604	0.778–3.308	0.201	
Year at university				
    Year 1	reference			
    Year 2	1.804	0.750–4.338	0.187	
    Year 3	1.741	0.698–4.341	0.235	
    Year 4+	2.249	0.805–6.281	0.122	
Judo experience	0.899	0.810–0.998	0.046	
BMI				
    normal + underweight	reference			
    overweight 25.0–30.0	1.130	0.488–2.615	0.776	
    obese > 30.0	3.134	1.413–6.951	0.005	
Support *; n (%)				
    Non-AT	reference			
    AT	1.447	0.749–2.797	0.272	
Competition level				
    regional	reference			
    national	0.854	1.012–16.856	0.663	
    international	3.196	0.794–12.858	0.102	
Practice days per week				
    1–5	reference			
    6–7	5.073	1.109–23.211	0.036	
Tournaments per season;				
    1–5 matches	reference			
    >6 matches	1.065	0.464–2.449	0.881	
* AT—had the support of an athletic trainer, Non-AT—had no support of an athletic trainer.

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References

1. Palumbo F. Ciaccioni S. Guidotti F. Forte R. Sacripanti A. Capranica L. Tessitore A. Risks and Benefits of Judo Training for Middle-Aged and Older People: A Systematic Review Sports 2023 11 68 10.3390/sports11030068 36976954
2. Bromley S.J. Drew M.K. Talpey S. McIntosh A.S. Finch C.F. A systematic review of prospective epidemiological research into injury and illness in Olympic combat sport Br. J. Sports Med. 2018 52 8 16 10.1136/bjsports-2016-097313 28954799
3. Frey A. Lambert C. Vesselle B. Rousseau R. Dor F. Marquet L.A. Toussaint J.F. Crema M.D. Epidemiology of judo-related injuries in 21 seasons of competitions in France: A prospective study of relevant traumatic injuries Orthop. J. Sports Med. 2019 7 2325967119847470 10.1177/2325967119847470 31211149
4. Madaleno F.O. Verhagen E. Ferreira T.V. Sampaio R.F. Mancini M.C. Fonseca S.T. Resende R.A. Comparison of incidence, prevalence, severity and profile of health problems between male and female elite youth judokas: A 30-week prospective cohort study of 154 athletes J. Sci. Med. Sport 2021 25 15 19 10.1016/j.jsams.2021.07.004 34326016
5. Nakazawa R. Sakamoto M. Dambadarjaa B. Khuyagbaatar E. Khadbaatar A. Fact-finding survey regarding judo-related injuries of judokas in developing country J. Phys. Ther. Sci. 2020 32 161 165 10.1589/jpts.32.161 32158080
6. Engebretsen L. Soligard T. Steffen K. Alonso J.M. Aubry M. Budgett R. Dvorak J. Jegathesan M. Meeuwisse W.H. Mountjoy M. Sports injuries and illnesses during the London Summer Olympic Games 2012 Br. J. Sports Med. 2013 47 407 414 10.1136/bjsports-2013-092380 23515712
7. Junge A. Engebretsen L. Mountjoy M.L. Alonso J.M. Renström P.A.F.H. Aubry M.J. Dvorak J. Sports Injuries During the Summer Olympic Games 2008 Am. J. Sports Med. 2009 37 2165 2172 10.1177/0363546509339357 19783812
8. Lystad R.P. Alevras A. Rudy I. Soligard T. Engebretsen L. Injury incidence, severity and profile in Olympic combat sports: A comparative analysis of 7712 athlete exposures from three consecutive Olympic Games Br. J. Sports Med. 2021 55 1077 1083 10.1136/bjsports-2020-102958 33219113
9. Soligard T. Steffen K. Palmer D. Alonso J.M. Bahr R. Lopes A. Dvorak J. Grant M.-E. Meeuwisse W. Mountjoy M. Sports injury and illness incidence in the Rio de Janeiro 2016 Olympic Summer Games: A prospective study of 11274 athletes from 207 countries Br. J. Sports Med. 2017 51 1265 1271 10.1136/bjsports-2017-097956 28756389
10. Soligard T. Palmer D. Steffen K. Lopes A.D. Grek N. Onishi K. Shimakawa T. Grant M.-E. Mountjoy M. Budgett R. New sports, COVID-19 and the heat: Sports injuries and illnesses in the Tokyo 2020 Summer Olympics Br. J. Sports Med. 2023 57 46 54 10.1136/bjsports-2022-106155
11. Lariosa C.J. Gozdowski D. Pietkiewicz S. Maciejewski R. Survey of judo injuries in physical education classes: A retrospective analysis J. Phys. Educ. Sport 2017 17 2034 2042
12. Finnish Institute for Health and Welfare, Finnish Environment Institute Helsinki Declaration to Protect Human and Plane-Tary Health for 2020s Available online: http://www.julkari.fi/handle/10024/139144 (accessed on 2 October 2020)
13. International Olympic Committee Injury Illness Epidemiology Consensus Group Bahr R. Clarsen B. Derman W. Dvorak J. Emery C.A. Finch C.F. Hägglund M. Junge A. Kemp S. International Olympic Committee consensus state-ment: Methods for recording and reporting of epidemiological data on injury and illness in sports 2020 (including the STROBE extension for sports injury and illness surveillance (STROBE-SIIS)) Orthop. J. Sports Med. 2020 8 2325967120902908 32118084
14. Sunagawa N. Recommended Methods for Sports Injury and Illness Surveillance: Japanese Society of Clinical Sports Medi-cine and Japanese Society for Athletic Training Consensus Document Jpn. J. Athl. Train. 2022 7 155 171
15. Bowen L. Gross A.S. Gimpel M. Bruce-Low S. Li F.-X. Spikes in acute:chronic workload ratio (ACWR) associated with a 5–7 times greater injury rate in English Premier League football players: A comprehensive 3-year study Br. J. Sports Med. 2020 54 731 738 10.1136/bjsports-2018-099422 30792258
16. Manzato A.L. Camargo H.P. Graças D.D. Martinez P.F. Oliveira S.A. Musculoskeletal injuries in judo practitioners Fisioter. E Pesqui. 2017 24 127 134 10.1590/1809-2950/16325024022017
17. Green C.M. Petrou M.J. Fogarty-Hover M.L. Rolf C.G. Injuries among judokas during competition Scand. J. Med. Sci. Sports 2007 17 205 210 10.1111/j.1600-0838.2006.00552.x 17501865
18. Kim K.-S. Park K.J. Lee J. Kang B.Y. Injuries in national Olympic level judo athletes: An epidemiological study Br. J. Sports Med. 2015 49 1144 1150 10.1136/bjsports-2014-094365 26216871
19. Alonso J.M. Tscholl P.M. Engebretsen L. Mountjoy M. Dvorak J. Junge A. Occurrence of injuries and illnesses during the 2009 IAAF World Athletics Championships Br. J. Sports Med. 2010 44 1100 1105 10.1136/bjsm.2010.078030 21106775
20. Alonso J.M. Edouard P. Fischetto G. Adams B. Depiesse F. Mountjoy M. Determination of future prevention strategies in elite track and field: Analysis of Daegu 2011 IAAF Championships injuries and illnesses surveillance Br. J. Sports Med. 2012 46 505 514 10.1136/bjsports-2012-091008 22522588
21. Engebretsen L. Steffen K. Alonso J.M. Aubry M. Dvorak J. Junge A. Meeuwisse W. Mountjoy M. Renström P. Wilkinson M. Sports injuries and illnesses during the Winter Olympic Games 2010 Br. J. Sports Med. 2010 44 772 780 10.1136/bjsm.2010.076992 20820057
22. Ruedl G. Schobersberger W. Pocecco E. Blank C. Engebretsen L. Soligard T. Steffen K. Kopp M. Burtscher M. Sport injuries and illnesses during the first Winter Youth Olympic Games 2012 in Innsbruck, Austria Br. J. Sports Med. 2012 46 1030 1037 10.1136/bjsports-2012-091534 23148325
23. Soligard T. Steffen K. Palmer-Green D. Aubry M. Grant M.E. Meeuwisse W. Mountjoy M. Budgett R. Engebretsen L. Sports injuries and illnesses in the Sochi 2014 Olympic Winter Games Br. J. Sports Med. 2015 49 441 447 10.1136/bjsports-2014-094538 25631542
24. Dvorak J. Junge A. Derman W. Schwellnus M. Injuries and illnesses of football players during the 2010 FIFA World Cup Br. J. Sports Med. 2011 45 626 630 10.1136/bjsm.2010.079905 21257668
25. Živković M. Bubanj S. Živković D. Stanković R. Bubanj R. Purenović T. Stojiljković D. Obradović B. Dimić A. Cvetković T. The frequency of illnesses in the population of high school athletes and non-athletes Acta Kinesiol. 2011 5 100 104
26. Ristolainen L. Toivo K. Parkkari J. Kokko S. Alanko L. Heinonen O.J. Korpelainen R. Savonen K. Selänne H. Vasankari T. Acute and overuse injuries among sports club members and non-members: The Finnish Health Promoting Sports Club (FHPSC) study BMC Musculoskelet. Disord. 2019 20 1 2 10.1186/s12891-019-2417-3 30611236
27. Pierpoint L.A. LaBella C.R. Collins C.L. Fields S.K. Dawn Comstock R. Injuries in girls’ soccer and basketball: A comparison of high schools with and without athletic trainers Inj. Epidemiol. 2018 5 1 8 10.1186/s40621-018-0159-6 29308538
28. Bejar M.P. Raabe J. Zakrajsek R.A. Fisher L.A. Clement D. Athletic trainers’ influence on national collegiate athletic association division I athletes’ basic psychological needs during sport injury rehabilitation J. Athl. Train. 2019 54 245 254 10.4085/1062-6050-112-18 30829537
29. Li T. Johnson S.T. Koester M.C. Hommel A. Norcross M.F. The impact of high school athletic trainer services on medical payments and utilizations: A microsimulation analysis on medical claims Inj. Epidemiol. 2019 6 1 7 10.1186/s40621-019-0194-y 30637568
30. Peterson C. Li T. Evidence for Economic Evaluations of Athletic Trainer Services J. Athl. Train. 2022 57 632 639 10.4085/1062-6050-0666.21 35142843
31. Tsukahara Y. Hieda Y. Takayanagi S. Macznik A. Risk factors for contracting COVID-19 and changes in menstrual and sleep cycles in japanese female athletes during the COVID-19 pandemic Sports 2022 10 114 10.3390/sports10080114 36006080
32. Keaney L.C. Kilding A.E. Merien F. Dulson D.K. The impact of sport related stressors on immunity and illness risk in team-sport athletes J. Sci. Med. Sport 2018 21 1192 1199 10.1016/j.jsams.2018.05.014 29934212
33. Hellard P. Avalos M. Guimaraes F. Toussaint J.F. Pyne D.B. Training-related risk of common illnesses in elite swimmers over a 4-yr period Med. Sci. Sports Exerc. 2015 47 698 707 10.1249/MSS.0000000000000461 25100341
34. Theberge N. “Just a normal bad part of what I do”: Elite athletes’ accounts of the relationship between health and sport Sociol. Sport J. 2008 25 206 222 10.1123/ssj.25.2.206
35. Walsh N.P. Recommendations to maintain immune health in athletes Eur. J. Sport Sci. 2018 18 820 831 10.1080/17461391.2018.1449895 29637836
36. Ezzat A.M. Schneeberg A. Koehoorn M. Emery C.A. Association between body composition and sport injury in Canadian adolescents Physiother. Can. 2016 68 275 281 10.3138/ptc.2015-59 27909377
37. McHugh M.P. Oversized young athletes: A weighty concern Br. J. Sports Med. 2010 44 45 49 10.1136/bjsm.2009.068106 19945974
