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Original article
Design of a protocol for large-scale epidemiological
studies in individual sports: the Swedish Athletics
injury study
Jenny Jacobsson,1 Toomas Timpka,1 Joakim Ekberg,1 Jan Kowalski,1 Sverker Nilsson,1
Per Renström2
1Section
of Social Medicine
and Public Health, Department
of Medical and Health
Sciences, Linköping University,
Linköping, Sweden
2Section of Sports Orthopedic
Surgery, Department of
Surgical Sciences, Karolinska
Institute, Stockholm, Sweden
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@liu.se
Accepted 18 February 2010
Published Online First
19 May 2010
1106
ABSTRACT
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.
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.
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.
METHODS
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.
INTRODUCTION
Data collection
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 defi nitions 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
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 defi ned 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 fi rst round of comments to the study coordinator, who assembled these into a case-study
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Original article
assessment document. When subsequent turns did not return
with significant changes in the document, the requirements
were considered fi nalised.
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 fi rst 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 fi nal 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
Table 1 Conditions for elite athletes in selected team sports and
athletics with relevance for the design of large-scale epidemiological
studies
Soccer8 11
Conditions for elite athletes
Practice in teams
Individual training
Set league schedule
Individual competition schedule
Coaches employed by club
Medical staff employed by club
Full professionals
√
–
√
–
√
√
√
Cricket14 Rugby12
√
–
√
–
√
√
√
Athletics*
√
–
√
–
√
√
√
–
√
–
√
(√)
–
(√)
*Conditions for Swedish elite athletes.
(√ ), hardly any.
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 fi nal 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 fi nal version.
RESULTS
Requirements on a study protocol in athletics
The primary requirement on the protocol was a correct defi nition 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 defi ned 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 defi nition used for the protocol follows, with some
alterations, the defi nitions 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:
(A) causes alterations in normal training and competition in
mode, duration, intensity or frequency from the current
A. Requirements analysis
Coordinator
Expert panel
Study protocol
requirements
Data to be
collected
Expert panel
Study procedures
Study protocol
design
Pilot tests
B. Study protocol design and testing
Coordinator
Expert panel
Figure 1 Display of associations between the (A) analysis of requirements and (B) study protocol specification.
Br J Sports Med 2010;44:1106–1111. doi:10.1136/bjsm.2009.067678
1107
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Original article
or subsequent training and competition sessions (partial
time loss injury)
(B) requires total removal from current or subsequent training and competition sessions (time loss injury).
The argument for using this defi nition 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 (fi gure 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 profi le 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).
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 profi le are collected using a paper-based
1108
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 fi lled
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
defi ned 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 affi rm a full clinical
diagnosis.
Injury report form
The occurrence of a perceived injury event is fi rst 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) fi nal 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
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Original article
ATHLETICS
Limited coach
supervision
Individual
practice
Individual training
programmes
behaviour
Wide
geographical
spread
Limited access to
medical staff
Over-reach/
overuse
Requirements
Self report of data
Adjusted exposure
definition
Adjusted injury event
definition
Psychological profile
e-diary
Questionnaires
Protocol
e-diary
Web system for data collection
and storage
Figure 2 Display of associations underlying the study protocol specification.
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.
Ethics
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
Br J Sports Med 2010;44:1106–1111. doi:10.1136/bjsm.2009.067678
athletes in each discipline (http://www.friidrott.se). 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 (http://www.
upplysning.se; 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)
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Original article
responded to the invitation, among whom 70% (n=321)
consented to participate in the study. Twenty athletes withdrew from the study after a fi rst consent due to retirement
from athletics. The fi nal study population thus consisted of
301 athletes. Ninty-one per cent (n=278) of the fi nal population contributed data over the web-based system the fi rst
study week. Thereafter, on average 74–83% of the athletes contributed reports each week, some athletes fi ling
their reports and submitting them each second or third
week.
DISCUSSION
We have presented a protocol for epidemiological injury surveillance in athletics, provided arguments for its design and
reported preliminary experiences from a fi rst 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 defi ned broad enough to cover conditions
resulting from loads at the borderline between over-reaching
and overuse. Nevertheless, the defi nition 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 profi le, 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 fi nd 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
1110
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.
Acknowledgements 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.
Contributors JJ, JK, SN, JE, PR and TT contributed to the analyses reported in
the study. JJ, JE and TT drafted the first version of the paper. All authors provided
comments on subsequent versions and have read and approved the final manuscript.
JJ, JK and TT act as coordinators of the Swedish athletics study. TT is the guarantor
of the study.
Demonstration versions of the online questionnaires (online appendices 1–4) are
available for download (http://www.imh.liu.se/samhallsmedicin/socialmedicin/
injury_epidemiology_individual_sports?l=en).
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.
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Original article
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Downloaded from bjsm.bmj.com on September 6, 2014 - Published by group.bmj.com
Design of a protocol for large-scale
epidemiological studies in individual sports:
the Swedish Athletics injury study
Jenny Jacobsson, Toomas Timpka, Joakim Ekberg, et al.
Br J Sports Med 2010 44: 1106-1111 originally published online May
19, 2010
doi: 10.1136/bjsm.2009.067678
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