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Abdominal Wall Injuries at the Elite Level in Australian Male Professional Cricketers
Journal of Postgraduate Medicine, Education and Research, October-December 2015;49(4):155-158
155
JPMER
Abdominal Wall Injuries at the Elite Level in Australian
Male Professional Cricketers
1David Humphries, 2John Orchard, 3Alex Kountouris
ABSTRACT
Background: Injuries to the abdominal wall, particularly mus-
cular injuries, are relatively common in professional cricketers.
The Cricket Australia injury database holds data on these injuries
over a 20 years span.
methods: This study is a combination of (1) a descriptive outline
of the parameters associated with side strains and abdominal
wall injuries in elite male cricketers, based on deidentied data
extraction from the Cricket Australia database from 1995 to 1996
and 2014 to 2015; (2) multivariate regression analysis of risk
factors for abdominal wall strains, taking into account the risk
factors of player position, player age and previous abdominal
wall injury history.
Results: There were 183 injuries recorded over a 20 years
period at Australian state or national player level. Signicant
risk factors in logistic regression analysis were: being a Pace
Bowler RR 10.0 (95% CI 3.1–32.1) and being 24 years old or
younger RR 3.4 (95% CI 1.7–6.8). Surprisingly, there was only
minimal risk increase, not reaching statistical signicance, for
recent injury in the same season (p = 0.18) and no association
at all with past injury in previous season (p = 0.99).
Discussion: The internal oblique muscle is reported the most
commonly injured component of the abdominal wall, the injuries
are overwhelmingly sustained by pace bowlers and the peak
incidence of the injury is in the early part of the cricket season.
Younger fast bowlers are more likely to be injured than older
ones. A history of abdominal wall strain in either the recent or
distant past does not increase or decrease future risk of strain,
which is in contrast to other muscle strains.
Keywords: Cricket, Fast bowling, Muscle strains, Side strains.
How to cite this article: Humphries D, Orchard J, Kountouris A.
Abdominal Wall Injuries at the Elite Level in Australian Male
Professional Cricketers. J Postgrad Med Edu Res 2015;49(4):
155-158.
Source of support: Nil
Conict of interest: None
JPMER
ORIGINAL RESEARCH
1-3Private Practice
1Department of Sports Medicine, The Sports Medicine Practice
Tasmania, Australia
2Department of Sports Medicine, Cricket Australia, Victoria
Australia
3Department of Sports Medicine, School of Public Health
University of Sydney, New South Wales, Australia
Corresponding Author: David Humphries, Private Practice
Department of Sports Medicine, The Sports Medicine Practice
Tasmania, Australia, Phone: 61362319225, e-mail: drdavidh@
internode.on.net
10.5005/jp-journals-10028-1167
INTRODUCTION
The Cricket Australia injury database (CA database)
tracks all injuries sustained by Australian cricketers who
have professional playing contracts at state or national
level. Each of the Australian states have a squad of
professional players and in recent years the formation
of a professional 20/20 format competition has meant
that all states also have at least one 20/20 format fran-
chise, the two most populous states have two franchises.
Cricket Australia has been collecting comprehensive
data on injuries sustained by contracted players since
1997 and some data sets have been maintained since
1994. The season injury statistics are published annually
in the Cricket Australia Injury Report,1 with comments
as to relative frequency of each type of injury, whether
the incidence appears to be increasing or decreasing
and so on.
The total database provides a unique resource in
cricket to gain insight into the characteristics of cricket
related injury and is particularly useful for mapping the
characteristics of injuries that are relatively infrequent
over any given season. This paper uses deidentied
data from the database to examine the nature of abdo-
minal wall injuries in professional cricketers. Previous
research has identied the characteristics of injuries to
the abdominal muscles in cricket2 and highlighted that
abdominal wall injuries are common in cricket (ranked
second highest incidence),1 particularly in pace bowlers,
and have high cost in regards to games missed (high
prevalence).1 These injuries have also been described in
a variety of other sports but apart from cricket, the only
sport in which such injuries occur relatively frequently
is baseball.3 For the purposes of this paper any injury
that occurred to the abdominal wall musculature or its
areas of attachment (including the lower ribs) has been
categorized as an abdominal wall injury.
METHODS
Deidentified data was obtained from the CA database.
The Australian Government National Health and Medical
Research Council Ethical Guidelines 20144 do not require
ethics approval when using de-identified data (negligible
risk of harm), therefore, ethics approval was not sought
for this project.
David Humphries et al
156
The CA database allows the injury data entered to
range between presumed diagnosis to specic diagnosis,
for example, an abdominal wall injury may be termed a
‘side strain’ or ‘a tear of the internal oblique muscle’. Using
the full breadth of entry terms in the database a total of
183 injuries over 20 Australian cricket seasons (1995–1996
to 2014–2015) were identied as tting the description of
an abdominal wall injury. The dataset was complete with
respect to injuries which resulted in missed playing time,
date of onset, number of matches missed, player details
and category (abdominal wall strain). There was a slightly
incomplete dataset with respect to specic injury diagnosis
(e.g. involved muscle) and specic injury onset (e.g. dur-
ing delivery, gradual onset) although for the majority of
injuries these details were available. Magnetic resonance
imaging (MRI) analysis of injuries was not done as
although the majority of injuries occurring in recent years
had MRI scans performed, the vast majority of those
injuries from the early years of the study did not have
MRI scans performed. The diagnosis of which muscle was
involved was provided by clinicians and the database did
not indicate whether this was an MRI conrmed diagnosis
or purely a clinical diagnosis.
MULTIVARIATE ANALYSIS
Occasions on which players sustained a side strain during
a competitive match were compared to those in which
no side strain occurred, with risk factors used to predict
these occurrences using a multivariate logistic regression
analysis in the Statistical packages for the social sciences
(SPSS) program. The risk factors analyzed were: (1) player
age (2) player position (3) history of recent abdominal
wall injury (earlier in the same season) (4) history of past
abdominal wall injury (not in the same season) (5) recent
bowling workload (6) era (year).
The results of these processes were then used to
examine a number of questions. These questions were:
what anatomical structures are most commonly injured,
what cricket activities are associated with the onset of
these injuries, which group of players are most likely to
sustain such an injury, are these injuries fatigue related,
is there any age group that is at greater risk of such inju-
ries. The reasons for asking these specic questions was
in part determined by what data subsets were relatively
complete and in part determined by published research
on a number of other cricket related injuries.
RESULTS
Of the 183 reported injuries, 140 were described as side
strains, side soreness or oblique muscle injury, noting
that ‘side strain’ is commonly used in cricket injury
parlance as indicating an injury to the oblique muscles
often near the anterolateral rib angle, (Fig. 1). There were
17 injuries described as rectus abdominis or abdominal
muscle injury, 12 costoiliac impingements, 13 miscella-
neous muscle injuries (including injuries to latissimus
dorsi, the intercostals and transversus abdominis) and
there was one undefined chest wall pain. The majority
(77%) of abdominal wall injuries occurred during matches
while the remainder occurred during training. Breaking
down the available data on the level of cricket being
played at the time of injury showed that 66% were related
to state or national team matches and the remainder to
grade or other level matches.
In 130 of these injuries, the activity leading to the onset
of pain was recorded; 99 of them occurred as a specic
event during the bowling delivery stride, 16 were of
gradual onset while bowling, ve occurred while batting,
two occurred during the bowling follow through, two
occurred at some undened point in the action of bowling,
two occurred while throwing, two occurred doing weight
training, one occurred while warming-up for bowling,
and one occurred while elding. Regression analysis
shows that the risk of abdominal wall injury while pace
bowling is ten times greater than for all other cricketing
roles. The low incidence of abdominal wall injury while
batting is in marked contrast to the injury prole of pro-
fessional baseball, where approximately half the injuries
occur in the action of batting.3
Of the 160 injuries, specically related to bowling,
there were 154 which occurred in fast or medium pace
bowlers, ve occurred in spin bowlers and one was not
specied. The majority (127) of the injuries occurred on the
lead arm side (that is the non-bowling arm), 17 occurred
on the bowling arm side and in 16 cases it was not speci-
ed which side was affected. Where a specic muscle
was identied as having been injured (46 cases) 56% of
the time it was identied as being internal oblique, 15%
Fig. 1: Typical MRI appearance of an internal oblique strain
Abdominal Wall Injuries at the Elite Level in Australian Male Professional Cricketers
Journal of Postgraduate Medicine, Education and Research, October-December 2015;49(4):155-158
157
JPMER
of cases involved rectus abdominis, 11% of the time it
was identied as external oblique, 9% were identied as
intercostals, 9% as latissimus dorsi and 2% were identi-
ed as transversus abdominis. Caution must be exercised
when interpreting this data set as it is not certain that
the injured muscle was determined by MRI scanning,
further it is obviously easier to determine if an injury
has occurred in rectus abdominis than differentiating
between internal and external oblique injury on clinical
signs alone.
The peak of abdominal wall injuries occurs early in the
cricket season, noting that the domestic cricket season in
Australia commences in September and nishes in March.
Twenty percent of all injuries that occurred during the
domestic season happened in October, with September
and October in combination accounting for 33.5% of all
injuries. Injury frequency slowly reduced in the months
thereafter (Graph 1).
The mean age of occurrence of abdominal wall injury
in bowlers is 25 years and 9 months.
MULTIVARIATE ANALYSIS
There were 38,781 player matches analyzed at state or
national level of which 87 (0.2%) led to a side strain
occurring (Table 1). The other side strains on the database
either occurred at a lower level match, a training session
or had a gradual or uncertain pattern of onset.
In bowlers under the age of 24, the risk of injury is
three times greater than for bowlers over the age of 30
and for bowlers 25 to 29 the risk was also twice the risk
than for bowlers aged 30 or over.
The risk of injury in fast bowlers was 10 times greater
the risk for spin bowlers (the next highest risk category)
and approximately 20 times greater risk than for batsmen
and wicketkeepers.
With respect to match type, the risk was highest in
Test cricket but with match units not adjusted for length
of game, so this was to be expected, as these are the long-
est games. Because fewer overs are bowled in one day
internationals (ODIs) compared to Test cricket the risk
per over it at highest rate in ODI cricket, although side
strains regularly occur in all forms of elite cricket.
There was a slightly higher risk of side strain in those
who had previously suffered a side strain earlier in the
season, although this did not reach statistical signicance.
This is in contrast to hamstring strain and other muscles
strains where recent injury is a highly signicant risk factor.
Past history (in a previous season) statistically bore no
relationship to risk of abdominal strain in future season
(relative risk 1.00, 95% CI 0.61–1.65). Although this pro-
bably means there is no relationship, it also means that
based on our analysis, if there is a relationship between
past abdominal strain and current injury, it is equally likely
that a past injury is protective as it is to be a risk factor.
DISCUSSION
The large data set presented here reflects similar findings
in previous studies of cricket related abdominal wall
injury. This larger data set gives confidence to some of
the accepted wisdom regarding who is at risk, what the
spread of pathology is and when these injuries occur. Two
areas stand out as particularly important.
The rst area is the timing of bowling related abdomi-
nal wall injuries during the season. A number of bowling
injuries have been shown to relate to the volumes of bowl-
ing done in the period preceding the injury occurrence
(5–8), these injuries typically peak in mid and late season.
This does not appear to be the case with abdominal wall
injuries, which peak early in the season and gradually
become less frequent over the remainder of the season,
although they can occur at any time during the season
(Fig. 1). This nding does suggest that at least some of the
injury risk relates to lack of specic muscle conditioning
rather than cumulative load. In turn that suggests that it
should be possible to mitigate some of the risk of injury
with targeted pre-season preparation and a graded tran-
sition from pre-season training to early-season matches.
Methods to monitor bowling intensity such as microtech-
nologies have the capacity to detect the relative intensity
of each delivery and should be considered during the
transition period from training to matches.9
The second area of interest is around the age of bow-
lers when they sustain abdominal wall injuries. Previous
studies have shown a propensity for bone related injury
to occur in young pace bowlers and soft tissue injuries
to occur more frequently in older bowlers.7,9 The data
Graph 1: Month of occurrence (frequency) of abdominal wall
injuries in bowlers
David Humphries et al
158
presented here suggests that the younger bowlers are
more susceptible to abdominal wall injuries, which is in
contrast to lower limb muscle strains where older players
are typical more likely to get injured. We can only offer
speculative theories for this age distribution until further
study. It is possible that the nature of this injury being an
insertional tear means that different mechanics are at play
compared to other muscle strains (which are more com-
monly mid-belly or musculotendinous junction rather
than insertional). A previous theory that the side strain
was a ‘rite of passage’ injury that would only occur once
(as the ‘ripping of the attachment’ would confer future
immunity) appears to be only partially correct. That is,
bowlers with a past history are no more, but no less, likely
to sustain a future side strain. Compared to other muscle
strains this makes side strains less likely to recur, but it is
important to note that there is no actual immunity either.
CONCLUSION
Abdominal wall injuries are relatively frequent in cricket
fast bowlers and relatively rare in all other cricket posi-
tions. They are not typically load related as many other
bowling injuries appear to be. It may be possible to reduce
the risk of injury by instigating improved specific pre-
season training for fast bowlers.
ACKNOWLEDGMENT
Extracts from this study were presented by David
Humphries at the 5th World Congress of Science and
Medicine in Cricket, North Sydney, March 2015 and
David Humphries and John Orchard at Cricket Australia
Medical Working Groups conference, Brisbane, May 2015.
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Table 1: Risk factors for 87 side strains occurring in state or national level matches from 1995–96 to 2014–15 seasons
Risk factor Type Signicance Relative risk 95% CI low 95% CI high
Player position Batsman 0.566 0.657 0.156 2.760
Wicketkeeper 0.474 0.437 0.045 4.215
Pace Bowler 0.000 90.983 3.105 32.098
Spin Bowler Ref group 0 0 0
Match type Domestic One Day 0.209 0.522 0.189 1.439
ODI 0.684 0.802 0.277 2.318
Shield 0.716 1.193 0.461 3.088
T20 cricket 0.115 0.386 0.118 1.262
Test match Ref group 0 0 0
Year range 2011–12 to 2013–14 0.393 1.296 0.715 2.349
1996–97 to 2004–05 0.667 1.121 0.667 1.884
2005–06 to 2010–11 Ref group 0 0 0
High recent bowling workload No 0.815 1.072 0.598 1.921
150 match overs bowled in last 3 months Ref group 0 0 0
Age group 24 years old or younger 0 3.434 1.742 6.770
25–29 years old 0.034 2.037 1.053 3.939
30 years old or over Ref group 0 0 0
Recent side strain Not this season 0.187 0.608 0.290 1.273
Injured this season Ref group 0 0 0
Past side strain No previous side strain 0.988 1.004 0.612 1.648
Injured in past Ref group 0 0 0
