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Design of a protocol for large-scale epidemiological studies in individual sports: the Swedish Athletics injury study
  1. Jenny Jacobsson1,
  2. Toomas Timpka1,
  3. Joakim Ekberg1,
  4. Jan Kowalski1,
  5. Sverker Nilsson1,
  6. Per Renström2
  1. 1Section of Social Medicine and Public Health, Department of Medical and Health Sciences, Linköping University, Linköping, Sweden
  2. 2Section of Sports Orthopedic Surgery, Department of Surgical Sciences, Karolinska Institute, Stockholm, Sweden
  1. Correspondence to Jenny Jacobsson, PT MSc, Section of Social Medicine and Public Health, Department of Medical and Health Sciences, Linköping University, Linköping SE-581 83, Sweden; jenny.jacobsson{at}


Background Epidemiological studies have mainly been performed on team sports. The authors set out to develop a protocol for large-scale epidemiological studies of injuries among elite athletics athletes.

Methods An argument-based method for investigation of complex design problems was used to structure the collection and analysis of data. Specification of the protocol was preceded by an examination of requirements on injury surveillance in individual sports and iterated drafting of protocol specifications, and followed by formative evaluations.

Results The requirements analysis shows that the central demand on the protocol is to allow for detailed epidemiological analyses of overuse injuries, which subsequently requires regular collection of self-reported data from athletes. The resulting study protocol is centred on a web-based weekly athlete e-diary enabling continual collection of individual-level data on exposure and injuries. To be able to interpret the self-reported data on injury events, collection of a wide range of personal baseline data from the athlete, including a psychological profile, is included in the protocol.

Conclusions The resulting protocol can be employed in intervention programmes that can prevent suffering among both adult elite and youth talent athletes who have made considerable life investments in their sport.

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A frequent sighting in the media coverage of the 2008 Beijing Olympics was an injured athlete. The agony of these injured sportspersons became matters of national concern in many countries, such as Sweden and China. A secondary effect was a public questioning of the training methods and the quality of injury prevention in the particular sport. In hindsight, the events and the debate raise questions about whether the practice schedules and loads are safe and not directly or indirectly hazardous for the athletes. Epidemiological studies of injury prevalence, incidence and patterns in athletics are scarce,1,,6 and the studies available lack the uniformity in methods and data definitions that would allow observed injury patterns to be generalised among populations.

In comparison, systematic injury surveillance has been implemented at the elite level in several team sports.7,,10 In many team sports, injury consensus groups have also formulated guidelines on how studies of injury epidemiology should be performed to allow between-study comparisons.11,,14 However, the contexts for injury surveillance in team sports and in individual sports such as athletics differ in several important aspects (table 1). For example, there are important differences between team and individual sports regarding everyday access to physicians and physiotherapists. In team sports, such as cricket and soccer, the majority of the elite clubs have medical staff employed.15 It is therefore necessary to reflect on the main characteristics of team and individual sports to distinguish the components of injury surveillance in team sports that are useful for the study of an individual sport.

Table 1

Conditions for elite athletes in selected team sports and athletics with relevance for the design of large-scale epidemiological studies

The aim of this study is to develop a protocol for large-scale epidemiological studies of injuries among elite athletics athletes. The protocol is to be used in planning of intervention programmes among adult and youth athletes.


An argument-based method for investigation of complex design problems16 17 was used to structure the collection and analysis of the data. Examination of requirements on injury surveillance in athletics was followed by iterated drafting of protocol specifications and formative evaluations. The protocol is exemplified by implementation in a national-level study in Sweden.

Data collection

A nominal group method18 was used for the requirements analysis. Two expert panels examined requirements on the data to be collected by the study protocol and the study implementation process, respectively (figure 1A). Individual expert's reviews of working documents were followed by telephone conferences. Requirements on the data to be collected were defined by a panel consisting of scientists and practitioners (n=8) with backgrounds in athletics coaching, sports medicine, epidemiology, biostatistics and medical psychology. To answer specific questions, international experts were consulted during a working seminar at the 2nd World Congress on Sports Injury Prevention in Tromsö, Norway 2008, and by personal communications. The panel examining requirements on implementation of the study in practice consisted of scientists (n=5) with backgrounds in sports medicine, statistics, health informatics and cognitive science. All experts provided a first round of comments to the study coordinator, who assembled these into a case-study assessment document. When subsequent turns did not return with significant changes in the document, the requirements were considered finalised.

Figure 1

Display of associations between the (A) analysis of requirements and (B) study protocol specification.

Data analysis

Data from the two-step requirements analysis processes were transferred to a study protocol specification procedure. Members of the two panels were merged into one design specification group (figure 1B). The task communicated to the group was to formulate a preliminary study protocol using the requirements, their personal expertise and the published literature. The experts first provided their individual comments, which were collected by a design process coordinator. Formulation of study protocol suggestions was performed independently by experts. Comments on each version of the working study design document were circulated to the entire expert group, and a consensus document was established. In the third and final step, the document was approved as the preliminary study design protocol.

Formative evaluations

A cognitive walkthrough19 review of the injury surveillance part of the preliminary protocol was performed. Six athletes and coaches individually reviewed the weekly surveillance section of the protocol. The instructions were to ‘walk through’ six weekly report scenarios, where the respondent: (1) had been injured but had recovered; (2) had been fit and was still fit; (3) had been injured and was still injured; (4) had been fit but was now injured; (5) had been injured but was now recovering with adjusted practice load; and (6) had entered the study with a previous injury. The reviewers were instructed to report if they noted any ambiguities or vague formulations, lack of suitable alternatives, or risk of misinterpretation and what the consequences of these observations would be. The reviewers' reports were analysed and the preliminary protocol revised into a prototype protocol.

The final evaluation of the prototype injury surveillance protocol was performed in a pilot study, which was carried out among adult and youth athletes (n=22). The survey data were used to revise the protocol into its final version.


Requirements on a study protocol in athletics

The primary requirement on the protocol was a correct definition of athletics injury at the borderline between functional over-reaching leading to improved accomplishments and overtraining leading to overuse injuries.20 21 Athletics athletes have been shown to sustain a large proportion of overuse injuries,1 2 4 5 22,,24 which implies that this injury category in particular has to be exactly defined and covered in epidemiological studies.

Second, to reflect the complexity of the sport, epidemiological data have to be collected directly from the individual athletics athletes. For instance, the training schedules can diverge substantially among individuals within a subdiscipline.25 It is therefore important to both extract individual data on exposure to practice and competition, and to include psychological and behavioural variables in the analyses. Coping strategies and different behavioural traits have been found to be associated with sports injury rates.26

Definition of athletics injury: protocol choice and arguments

The injury definition used for the protocol follows, with some alterations, the definitions previously used in athletics.4 24

A reportable athletics injury is any new musculoskeletal pain, feeling or injury that results from athletic training or competition and further leads to one or both of the following alternatives:

  1. (A) causes alterations in normal training and competition in mode, duration, intensity or frequency from the current or subsequent training and competition sessions (partial time loss injury)

  2. (B) requires total removal from current or subsequent training and competition sessions (time loss injury).

The argument for using this definition is threefold. First, the athletes will be handling surveillance reports themselves, and the injury recording will be performed from the athlete's subjective perspective, their experience of pain and/or feeling. Second, practice in athletics consists of several different components—for example, training with barbell and discipline-specific technique training. When athletes are unable to follow the original schedule due to injury or feeling, they routinely modify their practice schedule by exchanging elements. The concept of partial time-loss injury supports the search for identifying complex background patterns for overuse injuries. Third, to allow for comparisons with previous studies in athletics and other sports, injuries will primarily be identified by time loss, and at a secondary level the analysis will be complemented by investigations of tissue damage and the functional level of the athlete.

Means for athlete-level data collection: protocol choice and arguments

A majority of the adult athletics athletes, regardless of level of performance, perform their training sessions using a set programme and without immediate supervision. For this reason, we ruled out using coaches to assist with data collection. An alternative considered was to involve local physicians and physiotherapists, but this was not feasible due to the irregularity in individual practice schedules and was difficult in practice, since athletes live at various geographic locations.

We chose a combination of web-based injury surveillance system and postal mail survey to facilitate athlete self-report of data on exposure and injury events. We introduced the concept of a web-based ‘weekly e-diary’ to overcome difficulties in collecting the continuous information needed, that is, hours of training per week. Web-based survey methods have been reported to be reliable, in particular among young adults.27 28

Study protocol specification

The core of the protocol is deployed on an internet website for athlete self-report of data on exposure to athletic training and competition as well as injury surveillance (figure 2). The athlete enters the primary surveillance data themself on the website (for those under the age of 18 years with support from parents). Due to the wide geographical spread of athletics athletes, standardised physical examinations are difficult to administrate. No data on clinical biomechanical examinations are therefore included in the basic level of the protocol. Data on the athlete's psychological profile are collected using paper questionnaires by a postal survey, mainly because visual analogue scales have not been completely validated for use in electronic instruments/tools (for online surveys).

Figure 2

Display of associations underlying the study protocol specification.

Baseline questionnaires

Baseline data are collected in two sets. First, data are collected using a web questionnaire (online appendix 1) asking for demographic data and subject characteristics, ie, sex, age, height, weight, experiences from participation in athletics, main event/discipline and previous injuries. Second, data for the psychological profile are collected using a paper-based form created from a combination of validated instruments, measuring private and public body consciousness (BSC),29 psychological commitment to exercise,30 coping (BRIEF COPE),31 perceived motivational climate (Perceived Motivational Clittiate in Sport Questionnaire)32 and general health-related quality of life (EQ-5D).33

Athlete weekly e-diary

Data on athletic training and competition as well as injury surveillance are collected using an e-diary which is to be filled in weekly (online appendix 2). Each week, an alert is automatically sent out to participants' email addresses, inviting them to complete a questionnaire about amount of training and competition hours, and occurrence or absence of injury. In addition, the diary collects information on each athlete's training level, that is, whether the training is performed at full capacity or not, the number of practice sessions, medical contacts and general well-being. If the athlete reports any injury, they are requested to report modification of training, and numbers of missed training sessions in relation to that injury.

The study coordinator monitors the injury data reported in the weekly reports. If an athlete is absent from training due to a reported, but not diagnosed, injury event which has lasted longer than 3 weeks, the event is followed up by email or telephone interviews. Injury-related problems, as defined above that prevent the athlete from returning to full training, are requested to be examined by a sports physician or sports physiotherapist at the site to affirm a full clinical diagnosis.

Injury report form

The occurrence of a perceived injury event is first reported in the weekly e-diary. When an injury is reported, the athlete is provided with a link to an injury report form (online appendix 3) where additional questions on the current injury are to be reported. The form used for injury surveillance is a modified version of the injury report form reported by the soccer consensus and International Olympic Committee (IOC) groups.34 This injury report form has been shown to be feasible for the collection of injury data during athletic competitions.24 The original form34 was translated into Swedish using a back-translation procedure,35 and adjusted for online recording. All original items were included in our web injury report form, while questions were added regarding (A) injury event context (training/competition; indoors/outdoors), (B) specification of training method performed at time of injury (endurance, weight, sprint, etc), (C) anatomical site of the injury (left/right, back/front), (D) individual who made the preliminary diagnosis (trainer, medical profession, parent, etc) and (E) recurrence of earlier injury.

Injury closure form

When the injured athletes report in the e-diary that they have returned to normal athletic training, they are asked to complete a web-based injury closure form (online appendix 4) which asks for information regarding (A) time duration off full athletics training, (B) final diagnosis of the injury, (C) individual who made the diagnosis and (D) treatment received. There is also the possibility to provide personal remarks about the injury reported.

Protocol implementation: the Swedish athletics injury study

The web-based system for injury surveillance in the Swedish athletics injury study is based on a commercial product for collection of survey data over the internet (SiteVision V.2.5; Senselogic AB, Örebro, Sweden). The product enables definition of personal usernames and passwords to protect data from unauthorised use.


Ethical approval was obtained for the study from the Research Ethics Committee in Linköping, Sweden in November 2008 (registration number M-201-08). Informed written consent was collected from all study participants. For those under the age of 18 years, approval was collected from their parents. Informed written consent was also collected from all participants in the pilot studies.

Subject recruitment

We aimed to recruit ‘unique’ top-10 athletes in each discipline (19 disciplines for adults, 18 disciplines for youths), age group (adult and youths (under-18)) and sex. Four top-10 lists (two adult and two youth) for each discipline were thus compiled by the Swedish Athletic Association (SAA). The SAA maintains statistics for the top-25 adult and top-20 adolescent athletes in each discipline ( If an athlete was ranked among the top 10 in more than one discipline, the athlete was only included in their self-reported main discipline, and number 11 on the top 25 was upgraded to the top-10 list.

If an adult athlete's address was not recorded at the SAA, it was tracked and obtained from their athletics club. No such central record exists at the SAA for youth athletes. The addresses were instead collected from a website listing contact information for Swedish citizens (; Berlock Information AB, Enköping, Sweden). Letters of invitation were distributed by postal mail to all athletes targeted for the study and for whom addresses could be found in December 2008. The athletes received information about the forthcoming study, a consent form for participation, a request for a contact email address and a prepaid return envelope.

Six hundred and forty-seven athletes (369 adults and 278 youths) were informed about the study by letter and invited to participate. Seventy-one per cent (n=459) responded to the invitation, among whom 70% (n=321) consented to participate in the study. Twenty athletes withdrew from the study after a first consent due to retirement from athletics. The final study population thus consisted of 301 athletes. Ninty-one per cent (n=278) of the final population contributed data over the web-based system the first study week. Thereafter, on average 74–83% of the athletes contributed reports each week, some athletes filing their reports and submitting them each second or third week.


We have presented a protocol for epidemiological injury surveillance in athletics, provided arguments for its design and reported preliminary experiences from a first implementation. To maintain compatibility with previous studies, the ambition was that as many features as possible from existing guidelines for team sports are transferred to the athletics protocol. We found in the requirements analysis that the central demand on the protocol was that it had to allow for detailed epidemiological analyses of overuse injuries, which subsequently requires regular collection of self-reported data from athletes. These conclusions had several consequences for the detailed protocol design. First, the self-reported injury events had to be defined broad enough to cover conditions resulting from loads at the borderline between over-reaching and overuse. Nevertheless, the definition still had to be sufficiently exact to admit rigorous recording of what medically, by coaches and from the perception of individual athletes, are considered to be an injury. In addition, we found that in order to be able to interpret the self-reported data on injury events epidemiologically, a wide range of personal baseline data, including a psychological profile, needed to be collected from each athlete. To cope with this task, the traditional infrastructure for data collection and analysis had to be extended.

One motivation for large-scale epidemiological studies in athletics is the need to be able to tailor preventive interventions to subgroups of athletes, taking into account, for example, age group, sex and type of event. A particular need for prevention concerns the association between the physical and behavioural maturation of children and injury occurrence, taking into account injury risks both in the near future and later on in their sporting career. Competing with the best athletes at both national and international levels is today not only a goal for adult athletics athletes but also a part of the ambitions of youth athletes. For example, the world championships in athletics for the age group 17 years is today organised by the International Association of Athletic Federations every second year. In order to find safe ways to train elite children effectively, the IOC emphasises that international sports federations and national sports governing bodies must make use of scientific research methods to identify safe training volumes and develop injury-surveillance programmes also for this group of athletes.36 The elite youth athlete should not be encouraged to invest years of training in a sport where a promising career can be abruptly ended due to a preventable injury indirectly caused by lack of scientific knowledge. It is possible that only novel infrastructural means, such as the use of internet-based information technology, can make it feasible to offer these age groups in an individual sport, such as athletics, injury-prevention services. This is because systematic injury surveillance requires the collection of individual-level data over long periods of time and the performance of compound computations on these data sets.

In conclusion, the need for epidemiological evidence as a foundation for planning of preventive interventions in sports is today well established.37 38 However, in several individual sports, including athletics, this body of basic research is still missing. The protocol presented in this paper should be regarded as one means to overcome this shortcoming. However, before wide dissemination of the protocol, it is necessary to analyse and evaluate the international variations within the organisation and performance of athletics as an elite and community sport. For instance, an e-diary was included as a central part in the surveillance process. Introduction of the e-dairy demands a certain level of technological infrastructure and additional investments, which may not be available in other regions of the world. The implementation procedure must, before introducing web-based injury surveillance methods on a broad scale in athletics, be adapted to the conditions in the setting where the surveillance will be conducted.

What is already known on this topic

  • Systematic injury surveillance has been implemented at the elite level in team sports but seldom in individual sports.

  • Surveillance of injury prevalence and incidence in athletics has been scarce and lacked the uniformity in methods and data definitions that would allow observed injury patterns to be generalised among populations.

What this study adds

  • A formatively evaluated protocol for injury surveillance in athletics is reported.

  • Injury surveillance in individual sports requires collection of individual-level data over long periods of time.

  • Novel infrastructural means, such as internet-based information technology, makes it feasible to offer also individual sports injury-prevention services.


The study was supported by research grants from the Swedish Centre for Sports Research, the SAA and Linköping University.



  • Funding Swedish Centre for Sports Research and SAA.

  • Competing interests None.

  • Patient consent Obtained.

  • Ethics approval Ethics approval was provided by the Ethical Board at Linköping University.

  • Provenance and peer review Not commissioned; not externally peer reviewed.