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Sports injury epidemiology: American bull riding International SportMed Journal, Vo.8 No.2, 2007,
pp.78-86, http://www.ismj.com
Official Journal of FIMS (International Federation of Sports Medicine)
78
ISMJ
International SportMed
Journal
Review article
A comparison of injury rates in organised sports, with special emphasis
on American bull riding
*1
Dr Mark A Brandenburg, MD,
2
Mr Dale J Butterwick, ATC-C,
3
Dr Laurie A Hiemstra,
MD,
4
Dr Robert Nebergall, DO,
4
Mr Justin Laird, ATC
1
Department of Emergency Medicine, University of Oklahoma College of Medicine in Tulsa, Oklahoma, USA
2
Department of Kinesiology, University of Calgary, in Alberta, Canada
3
Banff Sport Medicine Group, in Banff, Alberta, Canada
4
Oklahoma State University Sports Medicine Team, Tulsa, Oklahoma, USA
Abstract
Objective: The authors set out to determine which sport in the literature has the highest injury rates. Data
sources: A systematic review of sports injury studies was performed using the PubMed database on the
National Library of Medicine website, using the key words: “Injury Incidence” in combination with each of the
sports: “boxing,” “football,” “hockey,” “rodeo,” “rugby,” and “soccer.” Study section: Using a 3-round selection
process, 2021 papers were reviewed. Those papers that did not report injury rates as a function of time were
excluded. Data extraction: Each paper underwent an independent review by two authors. Injury rates from
the papers reporting the top 5 injury rates for each sport were recorded and placed into an electronic
spreadsheet for comparison. All selected studies reported injury rates as a function of time, although the unit
of time was not always the same; therefore, simple extrapolation was made for all studies to make the unit of
time in hours. Data synthesis: The injury rate in bull riding was found to be 1440 injuries/1000 exposure
hours; 1.56 times greater than amateur boxing, 1.75 times greater than semi-professional rugby, 10.3 times
greater than American football, and 13.3 times greater than ice hockey. Conclusions: The authors conclude
that injury rates vary widely between contact sports and that American bull riding is the most dangerous
organised, spectator sport in the world. Keywords: sport injuries, injury rates, bull riding, sport injury
epidemiology
*Dr Mark A Brandenburg, MD
Dr Brandenburg is the Vice Chairman of the Department of Emergency Medicine at the University of
Oklahoma’s College of Medicine in Tulsa, Oklahoma, USA. He also serves as the Projects Director at the
Oklahoma Institute for Disaster and Emergency Medicine, and is the Programme Director of the Emergency
Medicine residency training programme currently in development. He supervises a broad array of research
activities in the areas of trauma, injury prevention and rodeo medicine. Dr Brandenburg’s work on head
injuries and protective headgear in bull riding has played a pivotal role in the growing popularity of the use of
helmets in this sport.
Recent honours include: C.T. Thompson Excellence in Trauma Care Award, Oklahoma State Medical
Association Award for best scientific publication in the OSMA Journal, and the University of Oklahoma
Crimson Apple Award for Medical Education Excellence.
*
Corresponding author. Address at the end of text.
Sports injury epidemiology: American bull riding International SportMed Journal, Vo.8 No.2, 2007,
pp.78-86, http://www.ismj.com
Official Journal of FIMS (International Federation of Sports Medicine)
79
Mr Dale Butterwick, ATC-C
Mr Butterwick is a Faculty Member of the Department of Kinesiology, University of Calgary, in Alberta,
Canada. He is also the Past President of the Canadian Pro Rodeo Sport Medicine Team, providing medical
support and injury management for professional rodeos, and the Professional Bull Riders Association in
Canada. He has published numerous sport medicine papers and has conducted the only large-scale
epidemiological studies on the sport of rodeo.
Recent honours include: Induction into the Canadian Athletic Therapists Association Hall of Fame (2006);
Induction into the University of Lethbridge Alumni Honor Society (2007).
Email: butterwi@ucalgary.ca
Dr Laurie Hiemstra, MD
Dr Hiemstra is a practicing orthopaedic surgeon with sport medicine fellowship training. Having recently left
the academic setting at the University of Calgary, she is currently in private practice with the Banff Sport
Medicine Group, in Banff, Alberta, Canada. Dr Hiemstra specialises in winter sports-related injuries and rodeo
medicine. She and Dale Butterwick organised and hosted the First International Conference on Rodeo
Medicine and Clinical Care.
Emails: hiemstra@banffsportmed.ca
Dr Robert Nebergall, DO
Dr Nebergall is a practicing orthopaedic surgeon in Tulsa, Oklahoma. USA. He is the Medical Director of the
Tulsa Regional Medical Center Sports Medicine Team, attending athletes in a broad spectrum of sporting
events, including NCAA college football, college wrestling, semi-professional hockey, NCAA college
basketball, semi-professional baseball and professional rodeo. He serves as the medical director at the
International Finals Rodeo every year in Oklahoma City, Oklahoma, USA.
Email: rnebergall@sbcglobal.net or julieg@tulsaorthosrg.com
Mr Justin Laird, ATC
Justin Laird is the Coordinator of the Tulsa Regional Medical Center Sports Medicine Team, USA. He has
worked for 8 years as athletic trainer in hockey, college wrestling, football, soccer and professional rodeo.
Email: julieg@tulsaorthosrg.com
Introduction
Researchers in sports medicine and injury
prevention today use injury epidemiological data
and statistics to guide them in making
recommendations to sporting organisations and
promoters on improving rules, regulations, and
equipment to make sports safer and more
meaningful for participants and spectators. Injury
epidemiological data in the medical literature
allow for comparative analyses to be conducted
on various sporting activities. Despite the
availability of this data, evidence-based
conclusions about which spectator sport is the
most dangerous have yet to be made.
American rodeo is a truly American sport with
roots deeply embedded in the Old West heritage
of the working cowboy. (1) Rough stock events
(i.e. bull riding, bareback riding and saddle
bronco riding) have been shown to have the
highest injury rates
2, 3, 4, 5
. Bull riding is a
mainstay event in American competition rodeo;
implicated in up to 31-37% of rodeo injuries,
making it the most dangerous event in rodeo
6, 7
.
The rate of injury associated with bull riding has
been shown to be two times higher than with
other major rodeo events (3.2 versus 1.39 per
100 competitor exposures)
8
. Bull riding
participants frequently suffer head and neck
injuries, sometimes resulting in permanent
neurological sequelae or death
9, 10
.
In an apparent effort to attract public attention
and fan support, many sports and other activities
have recently been referred to as ”extreme”,
including bull riding. In order to determine which
sports have the highest injury rates, this
investigation was created to compare injury rates
in such sports. Furthermore, in order to elucidate
the differences between such sports, the
importance of measuring injury as a function of
exposure time, rather than as competitions or
events, is illustrated in this present study. The
hypothesis of this study is that bull riders have the
highest reported injury rates per unit of time.
Sports injury epidemiology: American bull riding International SportMed Journal, Vo.8 No.2, 2007,
pp.78-86, http://www.ismj.com
Official Journal of FIMS (International Federation of Sports Medicine)
80
Methods
This project involved conducting a systematic
review of literature that has reported sport injury
rates as a function of time, and the prospective
collecting of exposure time data from American
professional bull riding events. The athletes were
professional bull riders in competitions at
Professional Bull Riders events, or at the
International Professional Rodeo Association
events, including the International Finals Rodeo
.
A. Systematic literature review
The purpose of the literature search was to
systematically review, identify and compare
studies reporting the highest injury rates for each
of the various sports. Since the goal was to find
the highest injury rates in sport, the authors did
not restrict the search by gender, age, or
classification of sport (i.e. extreme sports, contact
sports, high velocity sports, individual or team
sports), and included team sports with multiple
positions, such as ice hockey or football. To
allow comparison between the different sports,
the authors sought reported rates of injuries as a
function of time, usually per 1000 exposure
hours, the most widely used system for reporting
sport injury frequency
11
. No attempt was made
to meta-analyse the data as the authors were
only searching for studies that reported injury
rates approaching those found in the sport of bull
riding.
Round One:
Round One of the literature search
was to identify those publications in the English
language that report on the rate of injury for six
popular, organised sports: boxing, American
football, hockey, roller hockey, rugby and soccer.
These sports were chosen because they are
popular contact sports and likely to produce the
highest rates of injuries to athletes based upon
the clinical and research experience of the
authors. A literature search for sports injury
studies was performed using the PubMed
database on the National Library of Medicine
website. This search was based upon the
keywords: “Injury Incidence” in combination with
each of the sports: “boxing,” “football,” “hockey,”
“rugby,” and “soccer.” The term “incidence” was
used rather than “rate” in the search process
because it consistently generated the greatest
number of titles.
Inclusion criteria: The primary criteria for
selection were the reporting of data on the rate of
injuries as a function of exposure time (usually
reported as 1000 exposure hours). Each
selected paper met the following inclusion criteria:
1. Focused on one of the six contact sports
mentioned above;
2. Looked at all injuries occurring in the
specific sporting activity in question;
3. Reported the injury rate of the specific
sporting activity as a function of time.
Exclusion criteria: All titles were reviewed to
exclude papers that did not report the injury rate
of a sport, were not in English, or did not have
abstracts. All remaining abstracts were then
reviewed to exclude those that were not reporting
sport injury rate as a function of time. Papers
with any of the following exclusion criteria were
rejected:
1. Reported on any sport not included in the
group of contact sports listed above;
2. Looked only at one or a select group of
injury types;
3. Did not use exposure time as a
denominator in reporting the rate of
injury.
All titles were reviewed by each author to select
qualifying studies. Papers were excluded from
each round of consideration if both authors
agreed that exclusion had been met; otherwise,
the paper was promoted to the next round.
Round Two: Round Two involved reviewing the
abstracts of those titles promoted from Round
One. Upon reviewing the abstract, if both authors
made the determination that the paper did not
meet selection criteria then it was excluded from
further consideration.
Round Three: Round Three was the selection of
those abstracts reporting the highest injury rates
in each sport followed by the full article review.
Reviews were completed on the full manuscripts
of those studies reporting the highest injury rates
in each sport in a time-dependent manner. If
criteria for selection were met after each reviewer
read the paper, then the reported rate of injury
was recorded as a result for comparative analysis
(Table 1). Injury rates were converted to 1000
exposure hours (EH). The studies reporting the
top 5 injury rates from each sport were selected
and used in comparison to the injury rate data for
bull riding. If a particular sport is represented in
the literature by less than 5 papers, then reporting
of these rates was limited to the available data.
Sports injury epidemiology: American bull riding International SportMed Journal, Vo.8 No.2, 2007,
pp.78-86, http://www.ismj.com
Official Journal of FIMS (International Federation of Sports Medicine)
81
Table 1: The highest injury rates found in a systematic review of the medical literature, including the rates of
data subsets (i.e. defenders in ice hockey).
Highest
Injury Rates
Sport
(Injuries/
1000 EH) Design Country Reference
American Bull Riding 1440 Prospective
Canada/
USA
Butterwick DJ, Hagel B, et
al.
8
Amateur Boxing 920 Retrospective Ireland Porter M, O'Brien M.
12
Female Boxing 680 Retrospective USA Bledsoe GH, Li G, et al.
13
American Football
(High School) 140 Prospective USA
Anderson BL, Hoffman MD,
et al.
14
American Football 16 Prospective Germany
Baltzer AW, Ghadamgahi
PD, et al.
15
American Football
(High School) 3 Retrospective USA DeLee JC, Farney WC
16
Roller Hockey 304.9 Retrospective USA
Varlotta GP, Lager SL, et
al.
17
Ice Hockey 78.4 Prospective Sweden
Lorentzon R, Wedren H, et
al.
18
107.8 defense
Hockey (High School) 96.1
Prospective/
Retrospective
a
USA
Smith AM, Stuart MJ, et al.
19
Ice Hockey 66 Prospective Finland
Molsa J, Airaksinen O, et al.
20
Youth Ice Hockey
(ages 9-19) 50.9 M Prospective USA
Roberts WO, Brust JD, et
al.
21
64.8 M varsity
high school
Semi-Professional
Rugby 824.7 Prospective Australia Gabbett TJ
22
Amateur Rugby 694
b
Prospective Australia Gabbett TJ
23
Elite Rugby
(High School)
405.6 (<19
yrs)
Prospective Australia
Estell J, Shenstone B, et al.
11
Amateur Rugby
182.0
forwards Prospective Australia Gabbett TJ
24
English Professional
Rugby
139 Prospective UK
Stephenson S, Gissane C,
et al.
25
Soccer 44.4 Prospective USA
Putukian M, Knowles WK,
et al.
26
57.9 M
Soccer 50.4 M Prospective USA
Lindenfeld TN, Schmitt DJ,
et al.
27
50.3 F
Asian Football 64.7
d
Prospective Korea Yoon YS, Chai M, et al.
28
154.2
e
Professional Soccer 41.8
f
Prospective Sweden
Walden M, Hagglund M, et
al.
29
24
g
Professional Soccer 35.3 Prospective USA
Morgan BE, Oberlander MA
30
Sports injury epidemiology: American bull riding International SportMed Journal, Vo.8 No.2, 2007,
pp.78-86, http://www.ismj.com
Official Journal of FIMS (International Federation of Sports Medicine)
82
a
. Parents were responsible for
reporting player injury to the doctor
e
. Injury definition = complaints reported by
athletes
F = Female
M = Male
b
. 4th tournament match
f
. Match injury by English/Dutch teams
c
. Matches lost
g
. Match injury by other teams
d.
Injury definition = loss of playing
time
B. Data collection
Definition of bull riding exposure
The most recent prospective collection of injury
data in American rodeo reported injury rates in a
five-year prospective study of the Canadian
Professional Rodeo circuit
8
. In this article,
Butterwick reported injury rates from 30564
competitor exposures (CE) to a variety of rodeo
sporting events. The definition of competitor
exposure in that study was not time-dependent;
rather, it was defined as each time that one
competitor competed (attempted) in one event at
a rodeo (i.e. one bull ride).
This definition did not
measure the duration of the exposure. The
present comparative analysis requires such a
definition
Injuries in bull riding are known to occur as early
as when the rider first sits atop the animal while
still in the bucking chute (although this is
infrequent), thus the authors believe that the
exposure time should begin at that moment. For
the same reason (injuries infrequently occur to
riders after a successful disengagement from the
animal), the exposure time was concluded only
after either the animal exited the arena or the
rider reached the fence.
Units of measurement: The duration of an
exposure in bull riding is a matter of only seconds
and the reported injury rates are relatively high;
therefore, the units of injury rates initially were
recorded and are 1000 “Exposure Seconds”
(1000 ES). Data from other sports reported in
scientific citations were stated in “Exposure
Hours” (EH). The bull riding data were easily
computed into EH units for comparative analyses
using a ratio of 1/3.6.
Bull riding exposures: The authors
prospectively recorded the time of exposure in
seconds during 452 independent bull rides. Each
bull ride was performed by a professional bull
rider, at a sanctioned professional bull riding
event. Overall, there were 30 different
professional bull riding events at which they
collected data. Initially, one timer was used to
time the bull ride and to record the time.
However, this resulted in lost data as a second
ride could start (bull rider first sits atop a bull)
prior to the completion of the current ride. It is
unknown how many instances of lost data
occurred. However, for the last 22 events the
authors used two teams of timers, thus ensuring
that there was no lost data. Therefore the
average duration of a bull riding exposure was
determined by prospectively timing 452
professional bull riding exposures. This portion of
the study was not designed to collect injury data.
Thus the authors combined the mean exposure
time in this study to the injury rate in a five-year
epidemiological study which included bull riding
data, to determine the injury rate per unit of time
for bull riding
8
.
Results
A. Systematic Review
A total of 2021 titles were reviewed independently
by two authors. A total of 354 abstracts were
reviewed. The breakdown of the abstracts
reviewed was as follows: Boxing - 12, American
Football - 133, Hockey - 46, Roller Hockey - 3,
Rugby - 86 and Soccer - 74. The highest three
reported injury rates within the reviewed papers
were selected to represent the highest rates of
the sport.
Table 1 presents a comparison of sports with the
highest reported injury rates in six sports. Some
of these sports were presented as subsets (i.e.
defencemen in ice hockey). In addition, the
search for “hockey” presented an article on “roller
hockey” which met the inclusion criteria and is
therefore presented. This information is
presented as time-dependent exposure rather
than as per practice, game, or event.
Bull riding injuries per event were found to occur
at a rate 32.2 injuries per 1000 exposures in
Butterwick’s five-year prospective study. Using
the average exposure time of 80 seconds, the
rate of injuries is calculated to be 0.0004
injuries/ES or 1440 injuries/1000 EH. Other
sports with high injury rates are presented for
comparison.
Sports injury epidemiology: American bull riding International SportMed Journal, Vo.8 No.2, 2007,
pp.78-86, http://www.ismj.com
Official Journal of FIMS (International Federation of Sports Medicine)
83
B. Bull riding exposure
Four hundred and fifty-two bull riding exposures
were timed and recorded prospectively. The
timed exposures assumed a normal distribution
with mean exposure duration of 80 seconds and
a standard deviation of 33.94 (Figure 1).
Figure 1: Four hundred and fifty-two bull riding exposures were timed and recorded. The timed exposures
assumed a normal distribution with a mean exposure duration of 80 seconds and a standard deviation of
33.94.
Relative rates of injury data (Table 2) illustrate
that none of the sports studied exhibit injury rates
that are as comparatively dangerous as bull
riding. In particular, bull riders are approximately
10 or more times more likely to sustain injury than
are participants in team contact sports, such as
ice hockey and football, and about 36% more
likely to sustain injury when compared to amateur
boxing.
Table 2: The highest relative injury rates for each selected sporting activity are summarised using the highest
reported rates compared to published bull riding data.
Competition bull riding 1.0
Amateur boxing 0.64
Semi-professional rugby 0.57
Female boxing 0.47
Professional roller hockey 0.21
Asian soccer 0.11
Ice hockey (Defenders) 0.075
High-school American football 0.097
Sports injury epidemiology: American bull riding International SportMed Journal, Vo.8 No.2, 2007,
pp.78-86, http://www.ismj.com
Official Journal of FIMS (International Federation of Sports Medicine)
84
Discussion
The authors present the highest reported injury
rates for the six sports selected in this study,
including those of data subsets, such as
defencemen in ice hockey, in Table 1. Since one
goal of the study was to ensure that sports with
the highest reported injury rates were included,
there was no restriction on data collection by
gender, age, classification of sport, or to team
sports without individual position differences in
injury rate. This enabled the authors to report
those sports with the highest injury incidence,
regardless of such characteristics.
Most of the published reports on football injury
rates do not report data based upon exposure
hours, but rather on exposure events; in other
words, injuries per player-per game. The current
method of reporting exposure regards the time a
player was actually on the field. In other words, a
player who spent only 5 minutes on the field was
counted as an exposure in the same way as a
player who spent 50 minutes on the field. It is
therefore difficult to compare football data to other
football data and to other sports that typically
report injury rates based upon exposure hours
(EH). Despite this, the highest rates of injury
reported for American football were: 140
14
, 16
15
,
and 3
16
EH respectively.
The authors are also aware that examining only
those studies that used exposure time as the
denominator eliminates some studies that have
investigated sport injury rates using other
measurements; however, it is simply impossible
to compare one study type (i.e. exposure time) to
another type (i.e. exposure game or players).
The authors believe that this particular point is of
paramount importance to the future of sport injury
epidemiology research. They believe that the
methodology used to study sport injury rates
should become standardised at the international
level and should utilise the exposure time as the
denominator when reporting injury rates in future
studies. This would enable valid and reliable
meta-analyses to be conducted, without having to
eliminate large numbers of otherwise high-quality
studies from the review.
The authors do not exclude the possibility or even
the probability that there are outliers (i.e. those
studies with the highest injury rates) and that they
might represent bias or study errors. These
studies represent outliers for each sport and no
studies report higher rates; therefore they
represent the highest known possible injury rates
for each given sport. The data presented in this
study with regard to bull riding, represents the
sum total of epidemiologic data available on total
athlete injuries sustained in the sport, while the
same is not true for the other sports against
which bull riding was compared. The authors did
not attempt to average or meta-analyze the data
from the other sports; therefore the reader is
cautioned not to draw conclusions about the
mean or average rates of injury for these other
sports. Comparing the outlying (at the higher
end) sport injury rates of these other sports to the
data this study has on bull riding is the extent to
which the authors went to show that the injury
rate in bull riding is significantly greater than the
rates in the comparison of sports.
The bull riding data collection lost data when one
timer/recorder was used, because a second bull
rider’s time could theoretically start prior to the
completion of the current ride. This was
acknowledged by the individuals who were
recording the times; the authors then started to
use teams of timers/recorders. The potential for
an effect on results is mitigated by the normal
distribution of the timed exposures in Figure 1.
No attempt was made to control for sample sizes
in the reports of injury rates. Although some of
the data presented in Table 1 are from very small
sample sizes, the most likely effect of these small
sample sizes is to overestimate injury rates.
Moreover, because the authors only used the
outlier studies of sport injury rates in the
comparison to bull riding injury rates, it is almost
certain that the mean injury rates of these other
sports are far lower. Thus the overall presentation
of data in Table 1 supports the hypothesis that
bull riding has the highest injury incidence as a
function of exposure time, or per 1000 EH.
Conclusion
Until now, there have been no published reports
on the exposure time of American rodeo rough
stock events; therefore this study presents the
first such precise observation that an average bull
riding exposure is 80.26 seconds. Using
published injury rate data and assuming an
average 80-second exposure time, the injury rate
for that bull riding study is 1440 injuries per 1000
EH.
The next highest injury rate found in the literature
search was amateur boxing, with an injury rate of
920 per 1000 EH, while the second and third
highest reported injury rates were 825 and 680
injuries per 1000 EH in semi-professional rugby
and female boxing, respectively. According to
these data, the bull rider is 1.56 times more likely
to be injured than the amateur boxer, 1.75 times
Sports injury epidemiology: American bull riding International SportMed Journal, Vo.8 No.2, 2007,
pp.78-86, http://www.ismj.com
Official Journal of FIMS (International Federation of Sports Medicine)
85
more likely than the semi-professional rugby
player, and 2.1 times more likely to be injured
than a female boxer (Table 2).
As a result of these analyses, it is a simple matter
to conclude that there is a universal difference in
the injury rates between bull riding and most
other sports; and these authors, therefore, are
compelled to declare the sport of bull riding to be
the most dangerous organised sport in the world.
Address for correspondence:
Dr Mark A Brandenburg, Department of
Emergency Medicine, University of Oklahoma
College of Medicine-Tulsa, 2E-14, 4502 East 41st
Street, Tulsa, OK 74135-2553, USA.
Tel.: +27 (918) 660 3458
Fax: +27 (918) 660 3821
Email:
mark-brandenburg@ouhsc.edu
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