The Beijing 2022 Olympic Winter Games was the second Games held amid the COVID-19 pandemic,^[1] a situation that has impacted millions of lives in every nation. Moreover, to a certain extent, the pandemic has altered the way sporting activities operate. In the context of the spread of the Omicron variant of SARS-CoV-2 and high virus transmissibility during the winter months, it is important to ensure athletes’ health, safety, and ability to compete. Although recent data exist concerning injuries and illnesses from the Winter Olympic Games held in Sochi 2014^[2] and PyeongChang in 2018,^[3] injury and illness prevention and the protection of athletes’ health are key mandates for the International Olympic Committee. Systematic monitoring of trends in injury and illness over time can provide epidemiological data that are invaluable in maintaining the health of athletes.^[4] Each venue in Beijing, Yanqing, and Zhangjiakou set up a clinic and was equipped with ambulances to provide a variety of medical services. In general, injuries reported in winter sports are classified according to injury site, type, incidence, and severity.^[5⇓-7] Illnesses are classified and reported according to type, symptoms, and cause. However, there is a lack of knowledge on injury risk and illness occurrence among elite winter sport athletes during the COVID-19 pandemic. Thus, the aim of the present study was to evaluate the characteristics and frequencies of injury and illnesses occurring among all athletes during the Beijing 2022 Olympic Winter Games.

We conducted a retrospective study encompassing multiple sports events. A total of 231 ambulances were available in the Beijing, Yanqing, and Zhangjiakou competition areas to provide 24-hour emergency services. We collected information for all athletes treated for injuries and illnesses in the polyclinic and all other medical venues operated by Beijing 2022 medical staff between 4 and 20 February 2022, as well as information on ambulance transfers. These data were collected using an electronic medical record system.

After the Winter Olympics, we analyzed all the case data, clarified the statistical criteria, and separated the missing items to ensure the accuracy of the data analysis.

Injuries and illnesses were defined as new cases (presently existing, without full recovery) or recurring cases (occurrence after fully taking part in the Games) of incidents such as musculoskeletal complaints or concussions. We included athletes who were undergoing medical treatment incurred in competition or training, regardless of the consequences of their absence from competition or training. ^[8] In cases with several diagnoses involving multiple body parts injured during the same incident or multiple types of injury or illness occurring in the same or different parts of the body, only the most severe injuries/illnesses were registered.

In terms of injuries, we recorded the following information: athletes’ accreditation number, sport/event (whether the injury occurred in competition or training, whether the athlete was transferred), time of injury, injured body part, injury type, cause of injury, and estimated time lost from competition or training. We also recorded the following information for illnesses: athletes’ accreditation number, affected system(s), and main symptom(s).

We used the athletes’ accreditation number to query the athlete database to collect information on the athletes’ age, sex, and nationality. We treated all information with strict confidence and anonymized our medical database at the end of the Games.

This study was approved by the Ethics Committee of Beijing Emergency Medical Center (No. 2022-4-003), and written informed consent was waived.

We calculated injury and illness incidence as the number of injuries or illnesses occurring during competition or training, respectively, with incidence presented as injuries/illnesses per 100 athlete-days. Data were compared between male group and female group with respect to injury and illness risk using the Student’s t-test for continuous variables. We calculated the risk ratio (RR) of the number of injuries or illnesses between the two groups, assuming a constant hazard per group. We present injury and illness incidence with 95% confidence intervals (CIs). We considered two-tailed P values ≤0.05 as statistically significant.

In total, 2,897 athletes from 91 nations experienced injuries or illnesses. Among them, 1,593 were men, and 1,304 were women. Beijing 2022 medical staff reported 326 injuries and 80 illnesses. Thus, there were 11.3 injuries (95%CI: 10.1-12.4) and 2.8 illnesses (95%CI: 2.2-3.4) per 100 athletes over the 17-day period. Altogether, 11% of athletes incurred at least one injury, and 2% incurred at least one illness. Whereas most injured athletes experienced one injury, a total of 11 athletes had two or more injuries. The number of injured athletes was the highest in the skating sports (n=104), followed by alpine skiing (n=53), ice track (n=37), freestyle skiing (n=36), and ice hockey (n=35), and was the lowest in the Nordic skiing disciplines (n=20); no athletes were injured in the curling events. In terms of injuries by gender, 13.3% of women and 9.5% of men experienced at least one injury (RR=1.40, 95%CI: 1.14 -1.72, P=0.001), resulting in an incidence of 13.3 (95%CI: 11.5-15.2) injuries per 100 female athletes and 9.5 (95%CI: 8.1-11.0) injuries per 100 male athletes. With regard to illnesses by gender, 3.5% of women and 2.1% of men experienced an illness (RR=1.65, 95%CI: 1.07-2.56, P=0.023), with an incidence of 3.5 (95%CI: 2.5-4.5) illnesses per 100 female athletes and 2.1 (95%CI: 1.4-2.8) illnesses per 100 male athletes. Illnesses were reported in a variety of sports. The sports with more than 10 illness cases were skating sports (n=33) and Nordic skiing (n=22) (Table 1).

The most affected injury locations were the knee (22.1%), followed by the lumbar spine (10.4%) and thigh (9.2%) (Table 2). The incidence of knee injuries was roughly the same in ice and snow sports. Muscle strains (29.1%), impingement (16.6%), and contusion (12.6%) were the most common types of injury (Table 2).

In total, slightly more than half of the 326 injuries occurred during competition (n=171, 52.5%), 110 injuries (33.7%) happened during training, and 45 injuries (13.8%) happened during other sports-related activities, such as during warm-up exercises (Figure 1).

Of the 326 injuries, 14 (4.3%) led to an estimated absence from training or competition of more than 1 week. The injuries included 10 cases of strain/muscle rupture/tear/tendon rupture (1 neck/cervical spine, 1 thoracic spine/upper back, 4 lumbar spine/lower back, 1 thigh, 2 knee, 1 foot/toe), 2 meniscus/cartilage injuries (2 knee), 1 case of tendinosis/tendinopathy (foot/toe), and 1 case of impingement (knee).

Among the 326 injuries, 52 (16%) athletes were transferred to hospitals for further care, and 12.8% of the 406 athletes had an injury or illness. The rate of EMS was the highest for snowboarding (n=12, 42.9 injuries [95% CI: 22.3-62.4] per 100 athletes), ice hockey (n=11, 31.4 injuries [95%CI: 15.2-47.6] per 100 athletes), and freestyle skiing (n=9, 25.0 injuries [95%CI: 10.1-39.9] per 100 athletes) (Table 3 and Figure 2).

The number of athletes with illnesses (n=80) was the highest in skating (n=33) and Nordic skiing (n=22). A total of 50 illnesses (62.5%) involved dentistry (n=28) and ophthalmology/otolaryngology (n=22) and were mostly observed in skating venues (n=29), Nordic skiing (n=8), and ice track (n=6) (Table 4). The cause of illness was most often classified as other (preexisting, drugs) (n=52, 65%), followed by infection (n=22, 27.5%). The most commonly reported symptoms were dehydration/anaphylaxis/lethargy/dizziness/asymptomatic (other; n=53, 66.3%) and pain (n=23, 28.8%). A total of 6 (7.6%) illness cases were exercise-induced or caused by environmental factors (Table 4). Approximately 5% (n=4) of illnesses were expected to result in absence from further training or competition. Of those, one case of illness was expected to result in an estimated time loss of more than 7 d (arrhythmia, dizziness).

The aim of this study was to describe, analyze, and evaluate the incidence of injuries and illnesses among athletes competing in the Beijing 2022 Olympic Winter Games. The main findings of this retrospective study were that 11.3% and 2.8% of the 2,897 athletes experienced at least one injury or illness, respectively. This resulted in 11.3 injuries and 2.8 illnesses per 100 athletes during the Games. Furthermore, the characteristics of injuries and illnesses varied greatly according to sport event and athletes’ sex.

The incidence of injuries in the Beijing 2022 Olympics (11%) was slightly lower than those in PyeongChang 2018 (12%)^[3] and Sochi 2014 (12%)^[2] but comparable to those of Vancouver 2010 (11%)^[9] and London 2012 (11%)^[10] and slightly higher than those in Beijing 2008 (10%)^[11] and Rio 2016 (8%).^[12] Furthermore, 13.3% of women and 9.5% of men had at least one injury. The injury rate among female athletes was similar to their counterparts in PyeongChang 2018 (13.7%) whereas this rate among male athletes was slightly lower (11.9% in PyeongChang 2018). Injury rates in Beijing 2022 among both female and male athletes were lower than those in Sochi 2014 (14.9% and 13.2%, respectively). Thus, it can be concluded that the difference in the ratios of injuried males and females has increased in comparison with previous years. With seven new sport events in Beijing 2022, including women’s single bobsled, short track mixed team relay, mixed team ski jump, freestyle skiing big air (men’s and women’s), mixed team freestyle skiing aerials, and mixed team snowboarding cross, the proportion of female athletes was increased (45%) and athletes were more evenly distributed between men and women in comparison with past Games. This may have led to an increase in injury rates among female athletes. The frequency of injuries could not be obtained because of a lack of data on the number of athletes participating in each sport. However, the events with the most and least injuries were skating sports and curling, respectively.

For the location of the injury, similar to the PyeongChang 2018 Olympic Winter Games^[3] and the Vancouver 2010 Olympic Winter Games,^[9] the site most frequently injured during Beijing 2022 was the knee (22.1%). In total, 50 of 72 (69.4%) knee injuries occurred among athletes from skating sports, alpine skiing, and ice track. According to previous studies, knee injuries mainly occur in snow sports. The incidence of knee injuries in snow sports was 77.4% in the PyeongChang 2018 Olympic Winter Games.^[3] Similarly, Flørenes et al^[13] reported that the knee was the most frequently injured body region among athletes in the World Cup tournament, with incidences of 36% in alpine skiing, 29% in freestyle skiing, and 19% in snowboarding. Interestingly, the incidence of knee injuries was roughly the same for ice and snow sports in Beijing 2022, which can be inferred as a consequence of changes in environmental factors, venue or track design disparities, competition rules, or changes in equipment.

In approximately 60% of injuries during Beijing 2022, strain, impingement, and contusion were diagnosed as the top three injury types. In the PyeongChang 2018 Olympic Winter Games, the top three injury types were contusion, sprain, and laceration, accounting for approximately 28.5%, 13.0%, and 9.8% of all injuries, respectively.^[3] We found that skating sports caused the highest number of injuries, regardless of whether the knee was the primary injury location or strain was the primary injury type. Moreover, injuries during competition (n=95, 91.4%) accounted for the largest proportion of skating sports. High-speed sports, such as short track skating and speed skating, in which multiple athletes participated at the same time, were competitive and led to a higher risk of injury.

Injuries were unevenly distributed between training and competition (33.7% vs. 52.5%), and the results differed from those of PyeongChang 2018 (48% vs. 46%), Sochi 2014 (63% vs. 35%), and Vancouver 2010 (54% vs. 46%). Ice hockey was the only sport in Sochi 2014 and PyeongChang 2018 in which injuries occurred more commonly in competition than in training, as was the case in Beijing 2022. These results correspond with earlier findings.^[14-15] Ice hockey is a team sport with a lot of physical contact, and its intensity, speed, and likelihood of causing fatigue are much higher in competition than in training, resulting in athletes needing much time for recovery.

In a major sporting event such as the Olympic Games, any injury or illness, even if minor in severity and with no time lost, can lead to performance disorders and prevent athletes from achieving their goals, so they are very careful to avoid injuries. Athletes in Beijing 2022 incurred fewer severe injuries (4.3% of injuries were estimated to result in an absence of more than 7 d) than athletes in PyeongChang 2018 and Sochi 2014 (13% and 16%, respectively). These results are comparable to those of Vancouver 2010; however, there was a high percentage of missing data on injury severity in Vancouver 2010.^[9] The vast majority of athletes with an absence of more than 7 d had knee and spinal injuries. As knee and spinal injuries often result in long absences from training and competition, the prevention of spinal cord injury, spinal fracture, and severe knee ligament sprains, including injuries of the anterior cruciate ligament, is important.

An important task of medical services in sports events is to establish transportation and treatment systems for severely injured athletes. The reported rates of transportation to a hospital by ambulance during the Olympic Winter Games were 1.5% in Calgary 1998, 3.2% in Salt Lake City 2002, and 2.8% in Torino 2006.^[16⇓-18] In the Sapporo AWG, the rate of athlete transportation was 9.3%.^[19] The frequency of ambulance transfer in Beijing 2022 was significantly increased (12.8%, 52 of 406) compared with previous Games. All 52 athletes transported by ambulance were injured, and none were transported owing to illness. The most frequently transferred athletes were snowboard players, followed by ice hockey players. These events were covered by an emergency medical system, which ensured that ambulances were available 24 hours a day at each venue to provide appropriate treatment for all transferred athletes. The risk of injury varies for different sporting events; therefore, these data provide a basis for emergency medical treatment at major sporting events.

The incidence of illnesses in Beijing 2022 was significantly lower than those of PyeongChang 2018 and Sochi 2014 (2.8% of all athletes affected in Beijing vs. 9% in PyeongChang and 8% in Sochi^[2-3]). Furthermore, the PyeongChang illness incidence differed between female and male athletes, with slightly more women (57.5%, 46 of 80) than men (42.5%, 34 of 80) competing but with women in PyeongChang experiencing 61% more illnesses than men. These disproportionate rates have previously been reported in the Rio 2016 Paralympic Games^[20] and the 2009 Athletics and Aquatics World Championships.^[21,22]

Regarding the type of illnesses, according to previous reports, respiratory infections have accounted for a high proportion of illnesses in other elite sport events over the years.^{[2,3,20⇓⇓⇓⇓⇓⇓⇓-28]} However, there were only three cases of respiratory problems in Beijing 2022. A total of 50 illnesses (62.5%) were attributed to dentistry and ophthalmology/otolaryngology. Beijing 2022 was the second Games held amid the COVID-19 pandemic. To prevent the transmission of COVID-19 during the Games, organizers of Beijing 2022 formulated scientifically sound and pragmatic countermeasures. In particular, an innovative “closed loop” system^[29] was used; participants and venues were classified according to high, medium, and low risk levels and 12 stringent countermeasures were formulated. These included: a) requiring participants to be fully vaccinated at least 14 d prior to their departure for China and b) mandatory 21-day quarantine for those not fully vaccinated upon arrival in Beijing. As a result, the incidence of respiratory diseases, such as respiratory infections, declined significantly. We consider that this was also the main reason for the decrease in medical treatment of athletes owing to illnesses during the Beijing 2022 Games.

Regarding study limitations, such as the statistical classification of the preliminary design data not being detailed enough and the training of data entry personnel not being comprehensive enough due to the COVID-19 epidemic, some data were missing, which influenced the findings.

In summary, 11% of competing athletes had a reported medical encounter for a new or recurrent injury, and nearly 3% had at least one illness during the Beijing 2022 Olympic Winter Games. The incidence and characteristics of injuries and illnesses in training and competition varied greatly among different sports. Our results indicate that the type and distribution of injuries and illnesses among athletes changed owing to the COVID-19 pandemic. Our findings provide the basis for further studies on the etiology of injuries and illnesses among elite athletes. Moreover, as the COVID-19 pandemic continues around the world, the “closed loop” system also provides a reference for large-scale sporting events in the future.

We thank all the medical staff for their efforts to save the patient during the Beijing 2022 Olympic Winter Games, and we thank all patients involved in this study.

Funding: This study was supported by the Beijing Municipal Science and Technology Project (Z191100004419003), Capital’s Funds for Health Improvement and Research (2022-1-3031, 2022-2-3033), and Beijing Public Health High-level Scholars Development Program (2022-1-001).

Ethical approval: The study was approved by the Ethics Committee of Beijing Emergency Medical Center (No. 2022-4-003) and the requirement for written informed consent was waived. Under the terms of the approval, studies must undergo independent scientific review. Following approval, members of the research team were authorized to access the raw data for this study, which was granted permission by the Ethics Committee of Beijing Emergency Medical Center. The data used in this study were anonymized before use.

Conflicts of interest: The authors declare that they have no conflicts of interest.

Contributors: PDH, DG and JL (Jie Liu) contributed equally to this work. JJZ conceived the study idea for this article; PDH, DG and JL (Jie Liu) wrote the first draft; JL (Jing Luo), LXZ, and HXL collected data; SJT and SMN analyzed data; JJZ and YW suggested critical revisions. All authors were dedicated to the emergency medical services of the Beijing 2022 Olympic Winter Games. All authors have read and approved the final version of the manuscript and agreed with the order of presentation of the authors.