Athletics, also known as track and field, formed part of the first Olympics in 776 BC and were included in the first modern Olympic Games in 1896.1 The International Association of Athletics Federations (IAAF) was founded in 1912 and now has 212 member federations. IAAF organizes major athletics competitions worldwide, including the outdoor World Championships, which were established in 1983. In 2007, almost 2000 athletes from 203 federations registered for the 11th IAAF World Championships in Athletics in Osaka, Japan.
Although athletics is a popular sport, little is known about the injury risk for participants. Few studies on track and field injuries are found in the literature.2-8 Some studies focus on injuries in certain disciplines such as pole vault,9 long distance running,10 marathon,11,12 and decathlon.13 Substantial differences in study design, methods, injury definition, and population are hindrances to the analysis and comparison of these studies' results. However, reported injury rates such as “61% of the athletes suffered an injury of some kind during the season”4 or “an athlete incidence rate of 76% … in a 12-month period”2 indicate the extent of the problem.
Major sports events such as World Cups or World Championships provide an ideal environment to conduct injury surveillance studies because athletes of comparable skill-levels compete, the study period is defined by the event, and a high standard of environmental factors (such as the quality of playing fields and equipment) is guaranteed. Injury surveillance during sporting events should be a part of the duty of care to the participants to help make future events safer.14 Only a few injury surveillance studies have been conducted during major sports events, except in football and rugby.15 To the authors' best knowledge, no studies have been published thus far on injuries incurred during a major event in Athletics.
Based on an injury-reporting system previously established by the Féderation Internationale de Football Association (FIFA) for elite international football16-21 and handball22 tournaments, an injury surveillance system for team sports tournaments was developed and applied for all team sports tournaments during the 2004 Olympic Games.23 Acceptability of, and compliance with, the procedure was excellent.23 However, little experience existed concerning injury surveillance in competitions for individual sports. Since the International Olympic Committee (IOC) decided to extend the injury surveillance study to all sports during the 2008 Olympic Games in Beijing, the injury surveillance system was modified to be applicable for both individual and team sports.15 The IAAF conducted the current study during its 11th World Championship in Athletics as a pilot project for individual sports.
The aim of the current study was to record and analyze all sports injuries incurred in competition and/or training during the 2007 IAAF World Championships and to prove the feasibility of the injury surveillance system developed for the 2008 Olympic Games for individual sports.
In the present study, the IOC approach, based on the previous studies by FIFA-Medical Assessment Research Center (F-Marc), for injury surveillance during major sports events was applied.15 All disciplines of the 2007 IAAF World Championships (Table 3) were included. The implementation during the IAAF World Championships is summarized as follows. Medical representatives of all participating countries received a booklet with information about the study 1 month before the Championships and were requested to participate in the project by the IAAF. Two days before the start of the Championships in Osaka, team physicians were invited to an instructional meeting and were instructed on injury report form completion by 2 of the authors (JMA and JD). Team physicians, or, in their absence, team physiotherapists, were asked to participate in the study and to report daily all newly incurred injuries (or the non-occurrence of injuries) during the period of the Championships (25 August to 2 September 2007) on a standardized injury report form. They were requested to return them daily to the study center in the stadium warm-up area. In addition, to receive injury data on athletes from countries that did not have a team physician or physiotherapist, injuries were reported by Local Organising Committee (LOC) doctors at the medical centres in the stadium, warm-up area, and the hotels. During the Championships, two authors (JMA and PR) were available to answer questions and to motivate the team physicians.
Definition of Injury
Following the IOC and F-Marc approach,15,16 team physicians were asked to report “all musculo-skeletal injuries (traumatic and overuse) newly incurred during competition or training regardless of the consequences with respect to the athlete's absence from competition or training.”
Injury Report Form
The injury report form was identical to the one used during the 2008 Olympic Games.15 The following information was requested: athlete's accreditation number, sport/discipline, round/heat/training, date and time of injury, injured body part, type and cause of injury and estimated duration of the subsequent absence from competition and/or training. Definitions of these parameters are stated on the back of the form. The injury report form was available in 8 languages. The English version is published elsewhere.15
Confidentiality and Ethical Approval
The athletes' accreditation number was only used to avoid duplicate reporting from team and LOC physicians and to provide information on age, gender, and national federation of the athlete from the IAAF database. All injury reports were stored in a locked filing cabinet and were made anonymous after the Championships. Confidentiality of all information was ensured, and no individual athlete or team could be identified. Ethical approval was obtained from the Oslo University School of Medicine Ethical Committee.
Assessment of Feasibility
The feasibility of the injury surveillance system was assessed by analyzing the number of team physicians participating in the study and the related response rate as indicators of the acceptability and practicability of the report system and of the forms; the completeness of the filled-in forms as indicator of the comprehensibility and convenience of the requested information; the response rate per day as indicator of the compliance during the study period; comparison of reports by the team physician and LOC physicians at the medical centres as indicator of the objectivity and reliability of the reported information; the injury rate in different disciplines as indicator of the validity of the reported information; and the coverage of athletes as an indicator of the representation of the data and of the scope of the injury surveillance system.
Calculation of Exposure and Incidence of Injury
The number of competing athletes, participations, and incidence of injury was calculated in accordance with the IOC approach.15 The IAAF provided a list of athletes registered for the Championships. The competition schedule published on the Internet (http://osaka2007.iaaf.org/index.html) was used to calculate the number of competing athletes and the number of participations. The number of competing athletes was defined as all athletes who started at least once in a discipline. If an individual athlete participated in more than 1 discipline, the athlete was counted in each discipline. The number of participations was calculated by adding up the number of athletes starting in all heats, rounds, qualifications, and finals of a particular discipline or day. If an athlete started more than once in the same or a different discipline, each start was counted. In combined disciplines (eg, heptathlon) the starts in each subdiscipline were counted. The incidence of injuries in competition was calculated in relation to 1000 competing athletes. The incidence of training injuries was not calculated because athletes' exposures in training or training hours were not registered.
All data were processed using Excel and SPSS (SPSS Inc., Chicago, Illinois). Statistical methods applied were descriptive statistics, frequencies, cross-tabulations, t test and chi-squared test. Significance was accepted at P < 0.05.
Feasibility and Coverage of the Injury Surveillance System
Physicians or responsible physiotherapists of 49 national teams (24%) covering 1660 (84%) of 1980 registered athletes took part in the study. A total of 333 injury report forms were returned by the team physicians or physiotherapists, resulting in a response rate of 76%. Missing values were extremely rare for all variables. Half of the countries participating in the study, including 7 of 9 countries with more than 50 registered athletes, returned 8 or all 9 injury report forms. Thus, the team physicians' injury reports covered on average 68% of the registered athletes. In the first 6 days, between 39 and 44 (80 to 90%) of all participating team physicians returned the injury forms, but the response rate dropped in the last three days of the Championships.
In addition to the team physicians, LOC physicians reported daily about the injured athletes they had treated. On average, the national team medical personnel and LOC physicians reported a similar number of injuries (14% of the injuries were reported by both).
On the basis of the proportion of injuries reported by LOC physicians, it can be estimated that approximately 20 injuries incurred during the last 3 days were not reported by team physicians. However, no differences between the injuries reported in the first 6 and the last 3 days of the Championships were observed with respect to the proportion of injuries incurred in competition and in training or with respect to the proportion of time-loss injuries.
Frequency and Characteristics of Injury
A total of 192 injuries were reported; 110 in male athletes, and 78 in female athletes (the gender of 4 athletes was not reported). The age of the injured athletes ranged between 17 and 37 years with no significant difference between men and women (mean, 26.3; SD, 4.46). The injuries of men and women were similar regarding location, cause, and severity of injury but differed significantly for type of injury (χ2 = 28.9; P < 0.05). The incidence was 97.0 injuries per 1000 registered athletes or 53.0 time-loss injuries per 1000 athletes (exclusion of the athletes participating in 1500-m wheelchair would result in similar figures: 97.4 resp 53.5). Almost 80% (n = 153) of the injuries affected the lower extremity. The lower leg (n = 47; 24.5%) and the thigh (n = 42; 21.9%) were most frequently injured, followed by the foot (n = 25; 13.0%) and the knee (n = 18; 9.4%). The most frequent type of injury was strain (n = 49; 25.8%), followed by skin lesion (n = 33; 17.4%), muscle cramps (n = 28; 14.7%), tendinosis/tendinopathy (n = 24; 12.6%), contusion (n = 17; 8.9%), and sprain (n = 14; 7.4%). Six injuries were diagnosed as being a fracture, 1 as a ligament rupture, 3 as dislocation, 1 as a concussion, and 1 as a lesion of the meniscus. The most common diagnosis was thigh strain (n = 30; 15.8%). See Table 1 for details on injury diagnoses.
Circumstances and Causes of Injury
A quarter of the injuries (n = 49; 26%) occurred during training, 137 (71.4%) occurred during competition, 5 occurred during warm-up for competition, and 1 occurred during cool-down. The injuries incurred during warm-up before or cool-down after competition were analyzed as injuries during competition. Injuries in training and in competition were similar regarding the location of injury and subsequent time-loss from sport, but significant differences for type (χ2 = 38.5; P < 0.001) and cause of injury (χ2 = 27.8; P < 0.001) were observed. For details, see Table 2.
In most cases, the injuries were caused by overuse (n = 83; 43.5%) either with gradual (n = 32; 16.8%) or sudden onset (n = 51; 26.7%). Non-contact trauma and contact with another athlete were equally frequent (each n = 25; 13.2%). Recurrence of previous injury (n = 15; 8.0%), contact with object (n = 13; 6.8%), and weather conditions (n = 10; 5.2%) were more frequent than equipment failure (n = 6; 3.1%) and playing field conditions (n = 2; 1.0%). In 13 cases (6.8%), the cause of injury was defined as “other” or not specified.
Time-loss From Sport After Injury
Information in relation to time-loss from sport after injury was available for 188 injuries (97.9%). A total of 105 injuries (55.9%) were expected to prevent the athlete from participating in competition or training. Injuries with and without subsequent time-loss from sport differed significantly in location (χ2 = 22.3; P < 0.05), type (χ2 = 71.2; P < 0.001), and cause of injury (χ2 = 30.8; P < 0.001) but not with respect to sex or age of the injured athletes or the occurrence in competition or training. Time-loss injuries were mainly caused by overuse, non-contact trauma, or recurrence of previous injuries (for details see Table 2). Physicians estimated that 46 injuries (24.5%) would result in an absence from sports for up to 1 week, 38 injuries (20.2%) would result in an absence for more than 1 week but less than a month, and 20 injuries (10.6%) would result in an absence for more than 4 weeks.
Injuries During Competition
During the Championships, 1974 athletes started in 128 rounds, heats, and finals of 49 disciplines, resulting in a total of 3349 athlete participations. On average, 72.4 injuries per 1000 competing athletes or 42.7 injuries per 1000 participations were reported during competition. The respective figures for time-loss injuries were 42.0 per 1000 competing athletes or 24.8 per 1000 participations. Competition injuries were reported from all disciplines, except for hammer throw, javelin throw, women's 400 m, women's high jump, women's long jump, and 1500 m wheelchair.
Most injuries were reported in marathon (n = 22), followed by heptathlon and 1500 m and 3000 m steeplechase (each 14) and by 800 m (n = 11) and 10,000 m (n = 10). Time-loss injuries were most frequently incurred in marathon (n = 15), 3000 m steeplechase (n = 12), and heptathlon (n = 9). In relation to the number of competing athletes, the risk of a time-loss injury was highest in heptathlon, women's 10,000 m, women's 3000 m steeplechase, decathlon, and men's marathon (Table 3). In relation to the number of participations, the risk of time-loss injury was highest in women's 10,000 m (158 time-loss injuries per 1000 participations), men's marathon (118 time-loss injuries per 1000 participations), and women's 3000 m steeplechase (115 time-loss injuries per 1000 participations).
Injuries During Training
A total of 49 training injuries were reported from 22 disciplines. The number in each discipline ranged between 0 and 3, except for the 1500 m (n = 6). Injuries in training and in competition were similar regarding location of injury and subsequent time-loss from sport but significantly different in type (χ2 = 38.5; P < 0.001) and cause of injury (χ2 = 27.8; P < 0.001). The most frequent types of training injuries were strain (n = 15; 30.6%) and tendinosis/tendinopathy (n = 13; 26.5%). Two-thirds of training injuries were caused by overuse (Table 2). Three training injuries were expected to result in time-loss from sport for more than 4 weeks. Based on the number of registered athletes (n = 1980), 2.5% incurred a training injury during the Championships (1.1% a time-loss training injury).
This study aimed to register and to analyze all injuries of athletes participating at the 11th IAAF World Championships in Athletics in Osaka, Japan. To the authors' knowledge, this is the first injury survey during an international track and field competition.
The IOC injury surveillance system15 proved to be accepted by the team physicians and to be feasible in an individual sport competition. The injury report form was completed with very few missing values, and the data suggests that the injury surveillance system covered almost all athletes during the first 6 days of the Championships. However, data with respect to competition in the final 3 days (eg, decathlon and women's marathon) should be interpreted with caution; it is suspected that the team physicians' reports are not complete for this period of time. This can be explained partly by the fact that the team physicians usually reported the injuries the day after occurrence, and some of them were not able to return the forms on the last day or after the end of the Championships. Therefore, it is estimated that the injury incidence of the Championships is higher than reported.
At least 10% of registered athletes incurred an injury during the 9 days of the Championships. It is difficult to relate the figure to previous findings because no other publication on injuries during a major event in Athletics could be found in the literature and the incidence varied substantially between the disciplines. Bennell and Crossly2 and D'Souza4 reported in their retrospective surveys that, respectively, 76%2 and 61%4 of the athletes had incurred an injury in preceding year. In studies on youth track and field athletes, injury rates between 16% and 97% were observed.5,6-8,24 In their review on injuries in long distance runners, van Gent et al10 summarized that the incidence of lower extremity running injuries ranged from 19.4% to 79.3%. All of these studies had longer observation periods than a Championship. A study on marathon runners revealed an injury rate of 55% in the previous year and 16% in the previous month, and 18% of the starting runners reported at least 1 new running-related injury to the lower extremity during or immediately after the Rotterdam Marathon.11 In the current study, 12% of the male marathon runners incurred a time-loss injury. The figure for female marathon should be interpreted with caution because the discipline took place on the last day of the Championships.
The incidence of time-loss injuries in competition at the 2007 World Championships in Athletics (25 per 1000 participations) was similar to the incidence of match injuries in the 14 team sports tournaments of the 2004 Olympic Games (21 per 1000 player matches; 95% CI, 17.6 to 24.4). It was lower than in soccer and handball, similar to basketball, and higher than in field hockey, baseball, softball, volleyball, and water-polo.23 Such comparison, however, should be interpreted with caution because Athletics includes various disciplines (eg, 100 m sprint, hammer throw, marathon) in which 1 participation greatly differs from another, as does the injury rate. In the present study, the risk of a time-loss injury was highest in heptathlon, women's 10,000 m, women's 3000 m steeplechase, decathlon, and men's marathon. The injury incidence in all these disciplines was substantially higher than in any of the team sports tournaments of the 2004 Olympic Games.23 In heptathlon, 9 (23%) of the starting 39 athletes incurred a time-loss injury, and 5 of these injuries resulted in an estimated absence of more than 4 weeks.
Most of the injuries involved the lower extremity (80%), which is similar to previous studies in Athletics.2,5,24 The most prevalent diagnosis in the current study was thigh strain, which was the second most frequent diagnosis after stress fractures reported by Bennell and Crossley.2 During the Championships, 5 athletes (4 women, 1 man) incurred a stress fracture. The high incidence of stress fractures in track and field has been discussed previously.3,25,26
The majority of injuries in the current study were caused by overuse, which is in accordance with previous reports on injuries in Athletics.2,7,27 In contrast to the study of Bennell et al,2 who retrospectively analyzed injuries in a 12-month period, recurrence of a previous injury was a rare cause of injury in the current study because the team physicians were asked to report “newly incurred” injuries. Extrinsic causes such as weather conditions, equipment failure and playing field conditions were also infrequent.
The IOC injury surveillance system proved to be accepted by the team physicians and feasible in individual sport competitions. Results from the IAAF World Championships in Athletics are in accordance with previous publications on track and field, and they can be compared with studies of other sports tournaments using the same methodology. Approximately 10% of the registered athletes incurred an injury during the Championships. The risk of injury varied substantially among the disciplines, with athletes competing in combined disciplines, steeplechase, and long-distance runs having the highest hazard. In Athletics, preventive interventions should mainly focus on overuse injuries and adequate rehabilitation of previous injuries.
We highly appreciate the cooperation of the team physicians and the medical personnel of the IAAF World Championships who volunteered their time to collect the data for this project. We gratefully acknowledge the International Association of Athletics Federations (IAAF), the International Olympic Committee (IOC), and the Fédération Internationale de Football Association (FIFA) for their support and the funding of the study. We thank Ms. Agnes Gaillard very much for her valuable assistance in collecting of injury report forms and input of data during the IAAF World Championship in Osaka.
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