INTRODUCTION
Competitive, not recreational, sports athletes are under physical and psychological stress and expose athletes to the risk of injury [1]. Specially, collegiate athletes who combine athletics and academics at elite levels perform under considerable pressure [2], and this social environment could affect on the incidence of injury and illness [1]. When athletes are injured, it could limit participating in training and eventually can result in reduced their athletic performance [3]. In particular, musculoskeletal injuries cause restriction not only an athlete’s career but also life after retirement [4]. To minimize these negative results from being athletes, the International Olympic Committee (IOC) has been developed a system and reporting research results to systematically reduce injuries and illness of athletes [5].
Injury rates vary from sport to sport and appear differently by age, gender, etc. [5]. According to previous studies, the rate of injury by sport among Korean male athletes participating in the 2016 Rio Olympics was highest in wrestling (18.7%), followed by soccer (13.3%) and taekwondo (8%) [5]. The 2018 Summer Olympics showed notable rates of injury among 15-18 year olds participating in rugby (42.7 injuries per 100 athletes), boxing (32.9), wrestling (22.7), and futsal (22.1) [6]. In addition, Injuries to the lower limbs occur frequently in the knee (12.7-19.0%) and ankle (12.3-15.8%) and injuries to upper limbs such as shoulders (4.8-15.3%) and hands (5.0-8.9%) also occur frequently during sports activities [7,8]. Also, the statistical data of the Korea Olympic Committee reports that there are more injury incidences in male athletes than females who belong to schools and elite sports teams (https://www.sports.or.kr/), and males (71.8%) showed higher the incidence of injuries in collegiate athletes than in females (28.2%) [7]. And the consistently higher incidence of injuries reported in college athletes than in high school athletes can be seen in combat and ball sports [9,10].
Combat sports are divided into two categories involving direct blows between two players (hitting with fists or kicking) and events in which strength and skills is required to take down or immobilize the opponent to win [11]. Since combat sport is a contact sport and shows a proportional aspect to power, it is divided into different weight classes [12]. For example, taekwondo sparring and boxing, which take place through direct strikes, require wearing protective equipment to mitigate the impact from striking [13]. However, injuries caused by contact with opponents during a game account for more than half of the injuries [14], and wearing protective equipment does not appear to have a significant advantage in reducing injuries of athletes [15]. In addition, non-strike sports such as wrestling, ssireum, and judo use motions and techniques to takedown, throw, or immobilize an opponent without noticeable protective equipment, and 27.4% of injuries caused by takedown which is high portion [16,17].
In terms of team ball sports, agility and explosive power are required same as combat sports [11,18], which are essential physical factors and are related to instantaneous direction change and sprint ability [19]. Like competitive sports, American football and baseball also use protective equipment [18]. Athletes wear headgear/helmet, shin guards, chest/shoulder/knee protector, gloves, etc. to protect their bodies, which help reduce the impact of players colliding with each other and serve to prevent injuries [20]. On the other hand, ball games are team sports, where players perform their assigned roles in their respective positions, so overuse injuries are three times less than in individual sports that compete one-on-one [21]. However, team sports are under pressure from more repetitive activities and competitions, and the accumulation of excessive technical practice leads to injuries [9]. An important factor in preventing injury and improving sports performance is recovery [19], and sufficient recovery after practice or competition can greatly benefit to team performance [22].
METHODS
1. Participants
A total of 143 male collegiate athletes who registered in the ‘ Korean sport & Olympic committee’ in the 2021 season participated in this retrospective study to track injuries. 67 male collegiate athletes of 3 combat sports (ssireum, wrestling, taekwondo) and 76 athletes of 4 ball sports (football, soccer, baseball, sepaktakraw). All athletes voluntarily signed the consent form after receiving a sufficient explanation of the study’s purpose and procedure. The demographic characteristics of athletes were as follows: age (Combat, 21.1±1.35; Ball, 20.4±1.85), height (Combat, 178.4±6.37; Ball, 177.3±5.67), weight (Combat, 79.9±15.99; Ball, 78.7±11.56), BMI (Combat, 25.2±5.30; Ball, 25.0±3.09), career (Combat, 9.3±2.21; Ball, 8.6±3.44). This study was approved by the Institutional Review Board (2-1040709-AB-N-01-202112-HR-085-02).
In the case of collegiate athletes, unlike athletes in professional teams or national teams, the presence of a primary care physician or medical team is insufficient. So, collegiate athletes are not able to actively receive treatment for sports injuries. Therefore, there is a necessity to identify the risk factors of collegiate athletes’ injuries. There are also limited studies comparing the injury incidence and characteristics in combat and ball sports. The purpose of this study is 1) to analyze the mechanisms and rates of injuries experienced by athletes in combat and ball sports and 2) to find the methods for preventing injuries occurring in combat and ball sports.
2. Procedure and materials
A survey was conducted to investigate details of injuries that occurred during training among male collegiate athletes during the 2021 season when participation in competitions was restricted due to Covid-19. We wanted to know the injured body parts, types, and causes of injuries, and exercise time of participation by athletes in combat and ball sports. The questionnaire was prepared through a meeting between a sports medicine professor and two trainers who were certified as an athletic trainer. It was used by modifying and supplementing the IOC’s injury detection system questionnaire. The subject’s demographic information (age, height, weight) is shown in Table 1, and the questionnaire included the sports event, exercise time and frequency (individual exercise and main exercise), and injury code (location, type, and cause of injury).
3. Statistical analysis
To analyze all data, the IBM SPSS statistic WIN 27.0 version (IBM SPSS Inc., Chicago, IL, USA) was used. The demographic variables were described as mean and standard deviation (M±SD) calculated using descriptive statistics. The injury incidence rate (IR) means the annual number of injuries based on 1,000 hours of athlete exposures (AEs) during training and was calculated using the following formula: {(new injuries during the year)/(each athlete’s annual hours in training)×1,000}. A chi-square test was used to compare the injury location, type, and causes according to the sports.
RESULTS
The result of IR is in Table 2. It shows that the exercise participation time per person was higher in combat sports than in ball sports, and the number of injuries was lower. Therefore, injuries were recorded 2.14/1,000 AEs (95% CI; 1.89-2.39) in combat sports and 2.02/1,000 AEs (95% CI; 1.75-2.29) in ball sports.
Table 2.
Injury incidence rate of combat and ball sports
| Variables | Sports type | |
|---|---|---|
| Combat (n=67) | Ball (n=76) | |
| Practice injury | 328 | 384 |
| AEs | 141,076 | 142,054 |
| IR/1,000 AEs (95% CI) | 2.14 (1.89-2.89) | 2.02 (1.75-2.29) |
Injury location, types of injury, and causes of injury according to the two sports had significant differences, as shown in Table 3.
Table 3.
Injury location, types, and causes of combat and ball sports
In combat sports, injuries were most common in ankle (n=105, 34.8%), wrist (n=75, 24.8%), knee (n=60, 19.9%) and trunk (n=37, 12.3%). Elbow (n=9, 3.0%), head (n=8, 2.6%), and shoulder (n=7, 2.3%) showed similar frequency, and hip joint (n=1, 0.3%) showed the least. Ankle (n=60, 20.9%), knee (n=59, 20.5%), wrist (n=49, 17.1%) and trunk (n=40, 13.9%) were the top 4 parts in the ball sports. Elbow (n=22, 7.7.%) and hip (n=22, 7.7%) were the same, followed by shoulder (n=21, 7.3%) and head (n=14, 4.9%). There was a statistically significant difference between the two sports (χ2 =334.771, p <.001).
They appeared in the following order in the combat sports: sprain/ligament rupture (n=83, 26.4%), fracture (n=61, 19.4%), contusion/bruise (n=54, 17.2%), muscle spasm, strain/muscle tear, nerve/spinal cord injuries (each n=15, 4.8%), other bone injuries (n=31, 4.1%), meniscus/cartilage (n=10, 3.2%), capsulitis/bursitis, tendonitis/tendinopathy/tendon rupture, dislocation/subluxation (each n=8, 2.5%), other (n=6, 1.9%), conflict (n=4, 1.3%) fasciitis/tenosynovitis (n=3, 1.0%), tooth damage (n=2, 0.6%) and concussion (n=1, 0.3%). Ball game athletes were most often injured by sprain/ligamentous rupture (n=96, 28.3%), and followed by contusion/bruise (n=48, 14.2%), muscle spasm (n=30, 8.8%), fracture (n=27, 8.0%), strain/muscle tear (n=23, 6.8%), conflict (n=15, 4.4%), other bone injuries, stress fracture (each n=14, 4.1%), other (n=13, 3.8%), nerve/spinal cord injuries, capsulitis/bursitis (n=11, 3.2%), meniscus/cartilage (n=10, 3.0%), lacerations/abrasions/skin lesions (n=7, 2.1%), tendonitis/tendinopathy/tendon rupture, dislocation/subluxation (each n=6, 1.8%), fasciitis/tenosynovitis (n=4, 1.2%), concussion (n=3, 0.9%), tooth damage (n=1, 0.3%). There was a statistically significant difference (χ2 =205.099, p <.001).
From the combat sports, overtraining (n=133, 41.7%), lack of concentration (n=38, 11.9%), lack of practice (n=23, 7.2%), desire, lack of flexibility (each n=18, 5.6%), other (n=14, 4.4%), unstable environment/facility, high-level skill (n=12, 3.8%), lack of warm-up (n=10, 3.1%), deterioration of condition (n=8, 2.5%), lack of strength, excessive tension (n=6, 1.9%), climate/weather condition (n=3, 0.9%) appeared. Likewise, overtraining (n=94, 27.3%) was the highest cause of injury in the ball sports. Then, lack of rest (n=33, 9.6%), desire (n=32, 9.3%), lack of flexibility (n=25, 7.3%), recurrence (n=24, 7.0%), other, lack of strength (n=20, 5.8%), unstable environment/facility, lack of warm-up (n=17, 4.9%), deterioration of condition (n=16, 4.7%), excessive tension (n=11, 3.2%), high-level skill (n=9, 2.6%), lack of practice (n=8, 2.3%), climate/weather condition (n=3, 0.9%) appeared next. There was a statistically significant difference (χ2 =40.278, p <.05).
DISCUSSION
The survey was conducted on male collegiate athletes in combat sports (ssireum, wrestling, taekwondo) and ball sports (football, soccer, baseball, sepaktakraw) registered in each sport federation under the ‘ Korean sport & Olympic committee’ to analyze injuries in the past year. Among athletes of various age groups, the incidence of injury at the collegiate level was 23%, which is a relatively high rate [23]. Also, collegiate athletes reported approximately 2.2 times higher injury rate during their careers than high school athletes [7]. Therefore, it is thought that there is a need for measures to identify the causes and reduce injuries frequency of collegiate athletes. We need to investigate for collegiate athletes to not only maintain a healthy and sustainable life as athlete, but also prevent predictable injuries during training.
1. Injury incidence rate
In this study, IR was slightly higher in combat sports (2.14/1,000 AEs) than in ball sports (2.02/1,000 AEs). It is considered that athletes who participated in combat sports showed higher IR than in ball sports because they experienced contact with opponents of surfaces more frequently during such training. Due to the characteristics of combat sports, injuries are unavoidable when performing specific techniques such as kicking, striking, and grappling to win the game [24]. Injuries can also occur at any time during training and competition [25]. According to a study that conducted an online injury survey of athletes in elementary, middle, high school, college, and general levels of ball sports, injuries were more common during training than during matches [25]. Several previous studies have reported [25,26] that the IR during matches is higher than that of training, but Covid-19 has reduced the time spent playing matches and relatively high training hours and training volume, which supports the results of this study.
Combat sports require high levels of physical fitness and physical ability, and athletes perform high-intensity training on average 4-5 hours a day, 5-7 days a week to improve them [11,12]. Male collegiate athletes of taekwondo showed a high IR (2.91/1,000 AEs) in 2021 during competition and practice. The AEs were long in the previous research, so the IR of the previous one was higher than of the combat sports in this study. So, it is suggested that the more exposed of time to exercises, the more frequently injured.
Meanwhile, many injuries happen variously in ball sports [25]. Athletes participating in ball sports responded that the frequency of injury was the highest in college, middle school, and high school [25]. 68 Korean professional baseball athletes was reported a very high IR (1.74/100 AEs) during the competition [27]. As such, IR may vary depending on the characteristics of the sport, level, and sex. Therefore, injury prevention programs should be developed according to sports and positions, levels, or careers.
2. Injury location
As for the injured location, ankle injures appeared most frequently regardless of the sports and it was higher in the combat sports (34.8%) than in the ball sports (20.9%). Unlike this study, it has been reported that the ankle injuries accounted for 15% of all injuries in high schools and collegiate participating in team sports [28]. This was because of the dynamic movements (running, jumping, changing direction) used by athletes in team ball sports such as basketball, soccer, volleyball, etc. [28]. Common ankle injuries are caused by weakness of calf muscles, defects in proprioception, mechanical instability, deterioration of balance, and weakened eccentric contractility of the plantar flexors of the ankle joint [29]. To prevent ankle injuries in athletes, taping can be applied to improve postural control during dynamic movements [30], and appropriate rehabilitation exercises can be performed under the guidance of a specialist, such as resistance training, neuromuscular training, and blood flow restriction training to strengthen the muscles around the ankle joint, proprioception, and balance [31].
Wrist/hand was higher in combat sports (24.8%) than in ball sports (17.1%). In general, injuries to the lower extremities are common in combat sports [12], and the most common location of injury in combat sports were ankle/foot (8.32-46.53%), knee (15.08-21.44%), and wrist/hand (4.63-12.57%) in previous studies [14,16,32]. However, it is thought that the characteristics of combat sports such as ssireum and wrestling which are played using upper limbs. Ssireum and wrestling are performed the feet are fixed on the floor while holding and knocking down the opponent with the hand. Especially in ssireum, the wrist and hand are exposed to injuries due to mechanical effects of repeated pronation and overusing by the satba, which is a tool to hold the opponent [32]. Nerve damage arised by overusing can lead to carpal tunnel syndrome and such injuries can be prevented and reduce pain through nerve stretching and gliding exercises to improve joint flexibility [33].
Knee (20.5%) was the 3rd common injury and higher in ball sports. Similarly, knee (27.3-45.8%) were the most common injury, with the anterior cruciate ligament (ACL) often being injured in ball sports such as rugby and futsal [6]. It has been reported that the cruciate ligament is relatively often injured by mechanism of non-contact by moving cutting, pivoting, running, and performing acceleration/deceleration tasks to deceive the opponent in ball sports such as American football and soccer [34]. In addition, imbalance in the strength ratio between the quadriceps and hamstrings weakens the knee ligaments, which leads to knee injuries. So, coaches should incorporate postural stabilization, mobility of lower extremity joint, plyometric, and agility exercises into training pro-gram to prevent knee injuries [35], and hamstring strengthening exercises to improve the imbalance of the thighs.
3. Injury type
In the type of injury, sprain/ligamentous rupture was the most common in combat and ball sports, with 26.4% and 28.3%, respectively. Previous studies were consistent with the results of this study, showing that ligament injuries were highest. Injuries in combat sports, sprain (14.5-47.9%), contusion (16.0-28.6%), and laceration/abrasion (2.4-41.4%) appeared in the order [36], and another study, the epidemiological analysis of soccer-related injuries, showed sprain/strain (32.6-34.0%), fracture (22.2-23.2%), and contusion (16.9-17.7%) [37]. Steffen et al. (2020) observed that ligament rupture or sprains in the ankle (41.7-72.7%). Sprains often lead to chronic ankle instability with the highest incidence and 19-46% of recurrence rate in most ankle joints. Also, missed-time due to ankle injury was high in sports with high contact [38]. For prevention, strengthening, balance and proprioception training are known to be effective [28]. Based on these, if muscle strength and balance are improved, body stability might be increased. It may result in better injury prevention and sports performance.
Contusion was the second highest injury with a total of 102 cases in this study. According to the previous study on injury epidemiology of six collegiate sports, bruises (40.1%) was reported as the highest injury type [10]. This supports the fact that combat sports (17.2%) and ball sports (14.2%) accounted for a relatively high proportion in the study, and it is considered that all sports inevitably involve contact with athletes or objects. The reason why it appeared higher in the combat sports is because movement characteristics. For example, takedown, front kick, round kick occurs between the players, and it can hurt the skin, fascia, or muscles. Meanwhile, in ball sports, contusion can occur due to contact with the ball or frequent collisions between players [39]. However, it is thought that the time of contact during practice and competition is less than that of combat sports.
Fracture (19.4%) is mainly caused by the momentary action of physical force, and muscle spasm or strain (6.8-8.8%) is caused by overstretching or overload of muscle tissues [21]. In combat sports, some techniques apply direct impact or bend the body part and press with body weight [15,32], and it seems that fracture injuries occur in those movements. In ball sports such as American football, ice hockey, soccer, and baseball, strong throwing or kicking motions require an excessive range of motion for the body and cause muscle spasms or strain-related injuries to the joints in both upper and lower extremities [26]. By improving muscle and joint flexibility through training, athletes can reduce the risk of musculoskeletal injuries by about 30-120% [40]. Therefore, it seems necessary to include flexibility enhancement training.
4. Injury cause
Injury caused by combat sports showed overtraining (41.7%) was absolutely the highest, followed by lack of concentration (11.9%) and lack of practice (7.2%) in this study. Lemoyne et al. (2017) reported that long-term high-intensity training is associated with overuse injuries, and overuse injuries are high in combat sports because combat sports are performed one-on-one and unlike team sports, an athlete has to handle the whole game alone [4]. In the previous study that compared injury characteristics in youth and collegiate taekwondo sparring athletes, training concurrently with rapid weight loss in weight classes can cause overuse (8.5-10%) and overtraining (8.4-14.2%) injuries [12]. Athletes can improve their concentration and mental strength through practice alone [1], and the results of this study showed that athletes experienced a decrease in concentration due to lack of practice. To reduce injuries caused by these, it is necessary to control the training volume (frequency, time, intensity), promote rest and recovery, and avoid overtraining.
In ball sports, overtraining accounted for 27.3%, following lack of rest (9.6%), and desire (9.3%). Pluhar et al. (2019) reported that individual sports have internal pressure for failure and team sports have stress due to competition and team atmosphere [1]. These mental health issues are associated with sports injury, with 62.6% of 652 college athletes reporting that they had impaired their athletic performance [3]. It is considered that the athletes in ball sports, who do group activities, tried more than their own threshold to help the team and followed the excessive amount of training. Such accumulated fatigue would have resulted in overuse injuries. In other words, to prevent injuries to athletes, appropriate training needs to be conducted in efficient ways with sufficient time for rest and recovery.
In all sports, athletes are exposed to the risk of injury. The IR of combat sports may be relatively higher than ball sports because direct contacts, collisions, strikes are inevitable. However, athletes should under-stand the characteristics, movement mechanisms, and potential risk factors of the sports they participate in. It is important to consider the types of injury (facture, sprain, etc.) of body locations that are common used in intense motions, such as ankle, wrist, knee and reduce or improve the injury risk through prevention and strengthening exercises. The cause of injury can be found not only physical but also in psychological field, so it is necessary to manage them together.
5. Limitations
There are some limitations in this study. First, when the injury survey was conducted during COVID-19, athletes were restricted from participating in training and competitions, which may have led to different results. Second, 143 collegiate athletes were total participants, which was a small sample size for an injury epidemiology study. Lastly, since this study was a retrospective injury investigation, the number of injuries compared to the training participation time was relatively small. Usually, retrospective study of injury histories from athletes showed a low response rate. Considering this, when investigating past injury history, athletes should be given enough time to recall as many memories as possible, describe the training situation in detail, and create a comfortable atmosphere to recall memories so that you can collect accurate and numerous information.
CONCLUSION
Based on the results of this study, an imbedding injury surveillance system is a key to make a platform for identifying risk factors and developing interventions to prevent injury in both combat and ball sports. Also, coaches, supervisors, and trainers can incorporate specific exercise programs into their training that can strengthen locations with high frequency of injury.
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