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INCREASED RISK OF SPORTS INJURIES AMONG MEDICAL STUDENTS: CROSS-SECTIONAL STUDY

ABSTRACT Objective: To evaluate the nature and rate of sports injuries in medical students, as well as the risk factors at these events. Methods: All student-athletes (218) from a Medical School, integrated in at least one of the six team sport modalities (soccer, rugby, indoor soccer, handball, basketball, and volleyball) in 2017, were included. Injuries affecting their performance, regardless of time loss, were included. Athlete-exposure (A-E) was defined as one student-athlete participating in one practice or game. Results: Injury rates were significantly higher in junior medical students (1st - 3rd year) (7.58 per 1000 A-E, 95%CI = 6.11-9.06) than in senior medical students (4th - 6th year) (4.49 per 1000 A-E, 95%CI = 3.26-5.73) (p < 0.001). Multi-sports athletes had higher injury rates (10.69 per 1000 A-E, 95%CI = 8.22-13.17) than single-sport athletes (4.49 per 1000 A-E, 95%CI = 3.51-5.47) (p = 0.002). More than 60% of reported injuries occurred in the lower limbs and the mechanism that accounted for most injuries in games was player contact (51%); whereas in practice, it was non-contact (53%). Conclusion: Junior medical students present a higher injury rate than seniors. Medical students practicing more than one modality had a higher injury rate than those involved in just one sport modality. Level of Evidence IV, Cross-Sectional Study.


INTRODUCTION
Medical School is a highly demanding course with potential drawbacks for students. Rates of depression and anxiety disorders are higher amongst medical students than among their nonmedical counterparts, and problems such as burnout and substance abuse are more frequent. 1 Growing evidence that physical exercise could be an option in facing these problems exist. 2 Participating regularly in a group fitness classes, in opposition to exercising alone or not at all, can lead medical students to decrease their perceived stress and increase their the physical, mental, and emotional quality of life. 3 In Brazil, medical schools have a strong tradition in competitive sports tournaments. In addition to full-term classes and academic activities, medical students also participate in weekly practices and games in several sports modalities. Despite bringing several benefits to their quality of life, physical activity is a risk factor for musculoskeletal injuries. 4 The knowledge and surveillance of sports injuries are key components for preventing these events. According to van Mechelen, Hlobil, and Kemper, 5 to prevent sports injuries, a four-step procedure should be followed: 1) identify the problem; 2) establish cause and mechanism; 3) develop, evaluate, and implement interventions; and 4) reevaluate these strategies through continuous surveillance. The purpose of this study was to evaluate the injury rate and the nature of sports injuries in medical students, as well as the risk factors involved.

METHODS
All student-athletes from the University of São Paulo Medical School (a 6-year course), Brazil, integrated in at least one of the six team sport modalities (soccer, rugby, indoor soccer, handball, basketball, and volleyball) in 2017 were included, totalizing 218 participants. An appropriate institutional review board approved the project (CAPPesq 3.044.669 -28/11/2018) and each participant provided written informed consent before participation. The study is in accordance with the Helsinki Declaration of 1975, which was revised in 1983. Data from exposures and injuries for the 2017 season were collected separately. Regarding exposures, a form summarizing the number of practices and games and the average number of participants for each activity were submitted weekly by each team through Google forms based on the National Collegiate Athletic Association (NCAA) exposure report (Appendix 1). 6 The authors collected data regarding injuries retrospectively, after the last practice or game of the 2017 season, based on the NCA A questionnaire (Appendix 2). 6 Demographic data on age, gender distribution, year of Medical School, and number of sports practiced were also collected at the end of the season. A reportable injury had to meet the following criteria: 1) injury occurred as a result of participation in a university practice or game, and 2) injury resulted in restriction of the student-athletes participation or performance, regardless of time loss. Exposure was defined as one athlete participating in one practice or one game (athlete-exposure, A-E). 6 Data on injury mechanisms (non-contact, other contact, player contact, and unknown), site of injury by body part (head and neck, upper limbs, torso and back, lower limbs, and other system), and severity of injury were analyzed as percentages. Injuries that resulted in at least 21 days away from sports activities were classified as severe. A cross-sectional analysis was performed after injury and exposure data compilation. The analysis includes a comparison of injury rates in three categories: sports event (game vs. practice), year of medical school (junior athletes 1 st -3 rd year vs. senior 4 th -6 th year) and the number of sports practiced (single-sport athletes vs. multi-sports athletes). Multi-sports athletes were those integrated in at least two sports modalities. Injury rates were expressed as the number of injuries per 1000 A-E, 6 with a confidence interval of 95%. For comparison between injury rates, the chi-squared test was used, with p-value < 0.05

Sample characteristics
In total, 218 student-athletes, from the six-year medical course, were included. 57.3% were men and 53% were enrolled from 1 st to 3 rd year, with a mean age of 22.51 (± 2.6) years. 159 (73%) integrated a single sport modality, whereas 59 (27%) were multisport athletes.

Game and practice injury rates
The game injury rate (15.18 per 1000 A-E, 95%CI = 10.96-19.40) was 3.21 times higher than the practice injury rate (4.72 per 1000 A-E, 95%CI = 3.8-5.6) ( Table 1). These rates equal one injury every 3.3 games and 1 injury every 10.6 practices for a team of 20 participants, across all sports.   Figure 1 shows the distribution of injuries by body part. In both practices and games, more than 60% of the reported injuries were located in the lower limbs. Ankle (24.7%) and knee (14.6%) accounted for the most injuries. The incidence of ankle sprain was 1.40 per 1000 A-E (95%CI = 0.93-1.87) and incidence of anterior cruciate ligament (ACL) tear was 0.39 per 1000 A-E (95%CI = 0.14-0.63).

Games Practices
Injury mechanism Figure 2 shows the injury mechanisms in relation to practice and game. The mechanism involved in most injuries in games was player contact (51%) and in practice was non-contact (53%).

DISCUSSION
This study analyzes the injury rate and nature of sports injuries in medical students. Although enrolled in a high demanding course with 6 years of duration and full-term classes, medical students engage in weekly practices and competitive sports tournaments in Brazil. We found high rates of game and practice injuries (15.18 per 1000 A-E, 95%CI = 10.96-19.40 or one injury every 3.3 games and 4.72 per 1000 A-E, 95%CI = 3.8-5.6 or 1 injury every 10.6 practices for a team of 20 participants). A retrospective analysis of 396 student-athletes -including medical students -conducted by our group for the 2013 season, found similar rates. 7 The sudden increase in physical demand, considering that most students lead a sedentary lifestyle prior to entering Medical School, may explain the higher incidence of injuries in junior students (1 st -3 rd years) compared with seniors (4 th -6 th years), 7.58 per 1000 A-E 95%CI = 6.11-9.06 and 4.49 per 1000 A-E 95%CI = 3.26-5.73, respectively. A Chinese study with university athletes identified freshman students as a risk group for sports injuries. 8 These findings reinforce the importance of an adequate pre-participation assessment as well as a pre-season plan. Another possible risk factor of injuries in this population is the considerable number of students practicing more than 1 sport modality (27%). These multi-sports athletes presented a higher injury rate (10.69 per 1000 A-E, 95%CI = 8.22-13.17) than students practicing a single modality (4.49 per 1000 A-E, 95%CI = 3.51-5.47). The frequency of practices and games was strongly associated with physical activity-related injuries in a study with more than four thousand university students. 8 Moreover, it is well known that insufficient sleep time, less than six hours per day, is associated with fatigue injuries, 9 a very common concern among medical students. In contrast with NCAA, a high prevalence of non-contact injuries was found. This was the main mechanism of practice injuries (53%) and the second most common of game injuries (36%). Non-contact injuries represented just 36% and 17% of practices and game injuries in the NCAA, respectively (10). Medical students also had a high incidence of ACL tear (0.39 per 1000 A-E, 95%CI = 0.14-0.63) compared with NCAA (0.15 per 1000 A-E, 95%CI = 0.14-0.15). 10 The high incidence of non-contact injuries may reflect poor physical conditioning of medical students, reinforced by the fact that neuromuscular training programs decrease non-contact injuries such as ACL tear. 11 Regarding body part injuries, lower limbs represented most of practice and games injuries. Following previous literature, 12 the ankle was the most common location of injury (26%), followed by the knee (15%). However, considering severe injuries, the knee was the most affected (26%), followed by the leg and the ankle (21%). The well-established preventive programs to reduce lower limbs injuries are a potential alternative to improve sports safety among medical students. 13

CONCLUSION
Junior medical students presented a higher injury rate than seniors. Medical students practicing more than one modality had a higher injury rate than those involved in just one sport modality. Future preventive programs should focus on lower limb injuries, especially in junior medical students and in those practicing more than one sport modality.

Study limitations
This study may be susceptible to memory bias, meaning that a subject may have reported only the injuries that he was able to remember at the end of the season. Another important limitation

Time loss
The mean time loss was 40.1 days (95%CI = 30.62-49.59). There was a high incidence of severe injuries (48%). The knee accounted for most of the severe injuries (25.9%) followed by leg and ankle (20.7%), and shoulder (14.2%).

Injury rates by sport
As shown in Figure 3, the highest injury rates were: men's indoor soccer (8.75 per 1000 A-E), men's basketball (8.72 per 1000 A-E), and rugby (8.45 per 1000 A-E). 8

Injury Mechanism
Games Practices is that participating in a match accounted for 1 A-E regardless of time played, due to the technical limitation on accurately assessing time on court or field. Therefore, the expected injury rate may vary significantly among participants with drastically different amounts of minutes played per match.