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Journal of Sports Sciences
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Body composition characteristics of elite Australian
rugby union athletes according to playing position and
ethnicity
Adam J. Zemskia, Gary J. Slaterab & Elizabeth M. Broadc
a School of Health and Sport Sciences, University of the Sunshine Coast, Maroochydore,
Australia
b Australian Rugby Union, Sydney, Australia
c Sports Performance, US Olympic Committee, Chula Vista, CA, USA
Published online: 02 Jan 2015.
To cite this article: Adam J. Zemski, Gary J. Slater & Elizabeth M. Broad (2015): Body composition characteristics
of elite Australian rugby union athletes according to playing position and ethnicity, Journal of Sports Sciences, DOI:
10.1080/02640414.2014.977937
To link to this article: http://dx.doi.org/10.1080/02640414.2014.977937
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Body composition characteristics of elite Australian rugby union
athletes according to playing position and ethnicity
ADAM J. ZEMSKI
1
, GARY J. SLATER
1,2
& ELIZABETH M. BROAD
3
1
School of Health and Sport Sciences, University of the Sunshine Coast, Maroochydore, Australia,
2
Australian Rugby Union,
Sydney, Australia and
3
Sports Performance, US Olympic Committee, Chula Vista, CA, USA
(Accepted 14 October 2014)
Abstract
This study describes the body composition traits of modern-day elite rugby union athletes according to playing position and
ethnicity. Thirty-seven international Australian rugby athletes of Caucasian and Polynesian descent undertook body
composition assessment using dual-energy X-ray absorptiometry and surface anthropometry. Forwards were significantly
taller, heavier and had a greater total fat mass and lean mass than backs. Backs displayed a higher percentage lean mass and
lower sum of seven skinfolds and percentage fat mass. While no whole body composition differences were seen between
ethnicities, significant regional differences were observed. In the periphery (arm and leg) regions, Polynesians had a greater
proportion of fat mass (53.1% vs. 51.3%, P= 0.052, d= 0.5) and lean mass (49.7% vs. 48.6%, P= 0.040, d= 0.9), while in
the trunk region a lower proportion of fat mass (37.2% vs. 39.5%, P= 0.019, d= 0.7) and lean mass (45.6% vs. 46.8%,
P= 0.020, d= 1.1). Significant differences were also seen between Caucasian and Polynesian forwards in leg lean mass
(31.4 kg vs. 35.9 kg, P= 0.014, d= 2.4) and periphery lean mass (43.8 kg vs. 49.6 kg, P= 0.022, d= 2.4). Elite Polynesian
rugby athletes have different distribution patterns of fat mass and lean mass compared to Caucasians, which may influence
their suitability for particular positions.
Keywords: Caucasian, Polynesian, dual-energy X-ray absorptiometry, DXA, anthropometry
Introduction
Rugby union is an intermittent, full contact team
sport characterised by bursts of high-intensity run-
ning, heavy tackling and frequent body contact,
interspersed with periods of recovery. It requires a
unique combination of strength, skill, speed and
endurance (Duthie, Pyne, & Hooper, 2003). Since
becoming a professional sport in 1995, rugby has
become faster and more physically demanding
(Austin, Gabbett, & Jenkins, 2011; Eaves &
Hughes, 2003; Quarrie & Hopkins, 2007). This has
resulted in a greater emphasis being placed on
understanding the physiological demands of the
sport. These demands are position specific (Duthie
et al., 2003), and an athlete’s morphology together
with their physiology will influence their likely on-
field position (Nicholas, 1997).
Forwards are in continual close contact with
opposition players, and need to be strong and
powerful to gain and retain possession of the ball.
Being tall and having a heavier body mass is advan-
tageous in the forward positions (Duthie et al., 2003;
Nicholas, 1997; Quarrie et al., 1995), and has been
shown to positively correlate with scrummaging
force (Quarrie & Wilson, 2000) and competitive
success (Olds, 2001; Sedeaud et al., 2012). Excess
body fat may negatively impact performance by
reducing speed and acceleration (Duthie et al.,
2003), an outcome likely across all positions. Backs
control possession of the ball once obtained by the
forwards and are required to accelerate away from
opposition players to create scoring opportunities
and provide cover in defence. Speed and endurance
are among the most important physical attributes for
backs (Duthie et al., 2003; Nicholas, 1997; Quarrie
et al., 1995). However, as the game evolves, backs
are taking on more of the roles typically performed
by forwards, with a greater height and body mass
becoming increasingly important. Body composition
differences between forwards and backs are well
reported in the literature (Duthie et al., 2003;
Higham, Pyne, Anson, Dziedzic, & Slater, 2014;
Olds, 2001). Being able to assess, manipulate and
monitor the body composition of rugby athletes has
the potential to improve performance and has been
Correspondence: Gary J. Slater, School of Health and Sport Sciences, University of the Sunshine Coast, Maroochydore, QLD, Australia.
E-mail: gslater@usc.edu.au
Journal of Sports Sciences, 2014
http://dx.doi.org/10.1080/02640414.2014.977937
© 2014 Taylor & Francis
Downloaded by [University of the Sunshine Coast] at 17:48 05 January 2015
identified as being beneficial (Duthie et al., 2003;
Roberts, Trewartha, Higgitt, El-Abd, & Stokes,
2008).
The assessment of body composition is routinely
carried out on elite rugby populations, with dual-
energy X-ray absorptiometry (DXA) (Higham et al.,
2014; Pumpa, Murphy, Corish, & Wood-Martin,
2012) and surface anthropometry (Bell, 1980;
Dacres-Manning, 1998; Duthie, Pyne, Hopkins,
Livingstone, & Hooper, 2006;Holmyard&
Hazeldine, 1993; Maud & Shultz, 1984;Tong&
Mayes, 1995) being the primary measurement meth-
ods reported in the literature. DXA is able to quantify
total as well as regional distribution of bone mass, fat
mass and lean mass (Mazess, Barden, Bisek, &
Hanson, 1990). Surface anthropometry includes the
measurement of skinfolds at specific landmarks, and
in conjunction with the lean mass index (Slater,
Duthie, Pyne, & Hopkins, 2006)isabletoestimate
longitudinal within-subject proportional changes in
fat mass and lean mass. Both of these methods are
recognised as being reliable with good precision
(Ackland et al., 2012). Recently, DXA has been uti-
lised to look at specific regional body composition in
athletes, which is of particular interest in rugby popu-
lations due to the documented links between regional
body composition and speed (Kumagai et al., 2000;
Legaz & Eston, 2005). Specificdistributionoffat
mass and lean mass may play a more important role
than whole body composition in rugby performance,
something not previously investigated.
Rugby is an international sport participated in by
people from a range of ethnic backgrounds. An
increasing proportion of participants at the elite
level anecdotally appear to be of non-Caucasian eth-
nicity, particularly of Polynesian descent.
Furthermore, Olds (2001) identifies there were
enough New Zealand-born players (a nation with a
high proportion of Polynesian athletes) playing for
other countries in the 1999 World Cup to make up
two additional teams. Available evidence within
sedentary populations suggest significant differences
exist in body size, composition and fat distribution
between Caucasian and Polynesian individuals
(Craig, Halavatau, Comino, & Caterson, 2001;
Rush, Freitas, & Plank, 2009; Rush et al., 2004;
Swinburn, Craig, Daniel, Dent, & Strauss, 1996;
Swinburn, Ley, Carmichael, & Plank, 1999). This
evidence suggests that Polynesian athletes may have
different regional distribution of fat mass and lean
mass when compared to Caucasian athletes, which
may influence their suitability to particular positions.
The morphology and regional distribution of fat
mass and lean mass in Polynesian rugby athletes
has not been reported in the literature to date.
This study aims to describe the body composition
traits of modern-day elite rugby union athletes. In
particular, we will focus on comparing the morphol-
ogy between forwards and backs, and also between
Caucasian and Polynesian athletes, concentrating on
differences in regional distribution of fat mass and
lean mass, both in absolute and relative terms.
Methods
Participants
Forty elite rugby union athletes were recruited via
their involvement in the Australian Wallabies
national squad in 2012. Athletes’characteristics
were as follows (mean (95% confidence intervals)):
age 25.4 (24.4 to 26.4) years, height 187.2 (184.6 to
189.7) cm, body mass 102.5 (98.5 to 106.4) kg,
body mass index (BMI) 29.2 (28.4 to 30.0) kg · m
–2
,
sum of seven skinfolds 62.0 (56.9 to 67.1) mm and
lean mass index 57.6 (55.8 to 67.1) mm · kg
–0.14
. All
participants provided informed consent to partici-
pate in this study, and the research was approved
by the relevant Human Research Ethics Committee.
Experimental design
Participants undertook routine body composition
assessment during 2012 at the start and end of the
international season (3 months between assess-
ments) as per their Australian Rugby Union contrac-
tual obligations. The participants were in a well-
trained state at both time points given the start of
the international season coincided with the end of
the professional Southern Hemisphere season in
which they competed. DXA and surface anthropo-
metry measures were taken between 0 and 7 days
apart (average 3.6 days). Participants were assessed
either one or two times over the season. For consis-
tency, if a participant had two measures taken, the
measure corresponding to their highest lean mass
index value was used for analysis (average difference
in lean mass index values in participants with two
measures was 0.6 mm·kg
–0.14
). The highest lean
mass index value was used as theoretically this is
when the participants were in their peak physical
condition.
Body composition
Dual-energy X-ray absorptiometry (DXA). Measures
were taken using a fan-beam DXA scanner (Hologic
Discovery A, Hologic, Bedford, MA), with analysis
performed using Apex 12.7.3 software (Hologic,
Bedford, MA). The scanner was tested for consistent
calibration daily, with phantoms used as per manu-
facturer guidelines each day for quality control pur-
poses. All the scans were undertaken using the array
mode.
2A. J. Zemski et al.
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Scanning protocols were implemented as per tech-
niques previously described to maximise technical
reliability and minimise error (Nana, Slater,
Hopkins, & Burke, 2012a,2012b,2013).
Specifically, participants were scanned first thing in
the morning prior to food, fluid or exercise.
Participants were requested to remove all metal
items from their person, and lay supine on the scan-
ning bed as still as possible for the duration of the
scan. Participants were scanned wearing tight-fitting
sports shorts or underwear, and those too big for the
scanning bed undertook multiple scans. For posi-
tioning consistency, the same experienced and qua-
lified technician performed all measurements, and
the participant’s leg positioning was standardised
using a set width foot strap that was placed over
both feet anterior to the lateral malleolus.
The whole body scan was segmented into regions
manually during the analysis process by the same
technician that performed the scan. The arms were
separated from the trunk by positioning a cut
through the axilla and then to the medial head of
the humerus. The legs were separated from the trunk
by placing an angled cut through the bottom of the
ischium, forming a triangle with a horizontal line
over the top of the iliac crest. The head was sepa-
rated from the trunk by cutting just below the
mandible.
Surface anthropometry. A single Level 3 International
Society for the Advancement of Kinanthropometry
(ISAK) accredited anthropometrist with a technical
error of measurement of 1.7% for sum of seven
skinfolds took all measurements. Body mass was
assessed using electronic scales (A&D Mercury,
Adelaide, Australia) to 0.1 kg accuracy upon waking
with bladder voided. Skinfolds were assessed using
Harpenden calipers (British Indicators,
Hertfordshire, UK) to 0.1 mm accuracy at a time
later that day. All anthropometric equipment was
calibrated as recommended by the manufacturers.
Skinfold measurements were made on the right
side of the body using ISAK techniques previously
described (Norton et al., 2006), with a sum of seven
skinfolds calculated from the measures of the triceps,
subscapular, biceps, supraspinale, abdominal, mid-
thigh and medial calf skinfold sites. All measure-
ments were undertaken in duplicate to establish
within-day retest reliability. If the difference between
the duplicate measures exceeded 4% for an indivi-
dual skinfold, a third measurement was taken after
all other measurements were completed. The mean
of duplicate or median of triplicate anthropometric
measurements were used for all subsequent analysis.
Lean mass index was calculated using methods pre-
viously described (Slater et al., 2006).
Ethnicity
At the time of consent, the participants were
requested to provide researchers with the ethnicity
of their grandparents, and their own opinion of their
ethnicity via open-ended questions. It was made
clear that this was optional and would not impact
their involvement in the research.
A universally accepted method of distinguishing
an individual’s ethnicity was unable to be identified
due to the inherent difficulty in defining “ethnicity”
(Bradby, 2003). As this research is investigating the
phenotype expression and differences of ethnicity on
body composition based on differences previously
described in sedentary populations (Craig et al.,
2001; Rush et al., 2009; Swinburn et al., 1996,
1999), grandparental heritage was chosen as in pre-
vious research (Conway, Yanovski, Avila, &
Hubbard, 1995; Dowling & Pi-Sunyer, 1993;Rush
et al., 2009).
Statistical methods
The statistical procedures were performed with
SPSS 22 (SPSS Inc., Chicago, Illinois, USA).
Descriptive statistics including means, frequencies
and 95% confidence intervals were calculated on a
range of body composition variables discussed later.
An analysis of covariance with a generalised linear
model, involving the factors playing position and
ethnicity, was undertaken on the body composition
data. The covariate age was significant for a number
of the variables investigated, and for consistency was
retained as a covariate in all analyses. The means
reported are arithmetic means, while significance
testing was completed on the adjusted means.
Cohen’sdwas used to calculate effect size correla-
tion. Participants were considered outliers if they
were greater than two standard deviations away
from the mean in over eight of the body composition
variables analysed. A Bonferroni correction was not
used as all the comparisons were preplanned, and as
there was a likelihood of high correlations among
variables, this procedure would have acted as an
overcorrection.
Results
The initial study population consisted of 41 athletes,
with 1 athlete declining to participate. The remain-
ing athletes were arranged into groups based on their
on-field playing position, ethnicity and combination
of position and ethnicity.
Ten participants in this study identified the major-
ity of their grandparents as being of Tongan,
Samoan or Maori descent, while one participant
was identified as being of New Guinean descent.
Body composition of elite rugby union athletes 3
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Although New Guinea is regarded as being part of
Melanesia, for the purpose of this research, all 11
participants were classified as being of Polynesian
ethnicity.
After preliminary statistical analysis was underta-
ken, 3 athletes were removed from the final analysis
as they were identified as extreme outliers, leaving 37
athletes (Figure 1). The outliers comprised one
Polynesian back and two Caucasian forwards.
Whole body composition differences according to playing
position and ethnicity
No interactions (P> 0.05) between playing position
and ethnicity were found (Table I). Significant differ-
ences were found between forwards and backs using a
number of body composition measures, including
absolute mass, height, sum of seven skinfolds, lean
mass index, plus absolute and proportion of fat mass
and lean mass (all P< 0.001). No significant differ-
ences (P> 0.05) in whole body composition were
seen between Caucasians and Polynesians.
Regional body composition differences according to
playing position and ethnicity
Table II describes the regional body composition
differences according to playing position and ethni-
city measured by DXA. There was a significant
interaction effect between position and ethnicity in
the absolute mass and proportional regional mass
distribution of lean mass in the legs, and absolute
mass in the total peripheries (arms and legs).
Significant differences were seen between
Figure 1. Flow diagram of the study population.
4A. J. Zemski et al.
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Caucasian and Polynesian forwards in absolute leg
lean mass (31.4 kg vs. 35.9 kg, P= 0.014, d= 2.4),
proportional regional leg lean mass distribution
(34.9% vs. 36.5%, P= 0.033, d= 1.8) and absolute
periphery lean mass (43.8 kg vs. 49.6 kg, P= 0.022,
d= 2.4). No differences (P> 0.05) were seen
between Caucasian and Polynesian backs in these
measures.
Significant differences (P< 0.05) were seen
between forwards and backs in all body regions in
absolute mass distribution both in fat mass and lean
mass using DXA (Table II), and in fat mass using
surface anthropometry (Table III), with forwards
having higher amounts of fat mass and lean mass in
all regions. There were also proportional regional
mass distribution differences noted in fat mass
Table I. Whole body composition differences using DXA and surface anthropometry measures according to playing position and ethnicity
(mean (95% confidence intervals)).
Position n= 37 Ethnicity n=37
Forwards n= 20 Backs n= 17 Caucasian n= 27 Polynesian n=10
Height (cm) 191.0 (187.7 to 194.3) 182.6
a,
* (180.0 to 185.3) 187.8 (185.0 to 190.5) 185.5 (179.6 to 191.4)
Mass (kg)^ 111.7 (108.1 to 115.2) 91.7
a,
* (89.1 to 94.3) 101.4 (97.4 to 105.5) 105.3 (95.5 to 115.2)
BMI (kg · m
–2
) 30.6 (29.7 to 31.6) 27.5
a,
* (26.8 to 28.2) 28.7 (28.0 to 29.4) 30.5 (28.5 to 32.5)
Sum 7 skinfolds (mm) 73.1 (67.7 to 78.4) 49.0
a,
* (45.4 to 52.5) 62.0 (56.0 to 68.0) 62.1 (51.8 to 72.4)
LMI (kg/sum 7 mm
0.14
) 61.3 (59.5 to 63.2) 53.3
a,
* (51.6 to 55.0) 57.1 (55.2 to 59.0) 59.1 (54.7 to 63.6)
Bone mass (kg) 4.5 (4.3 to 4.7) 3.9
a,
* (3.7 to 4.0) 4.1 (4.0 to 4.3) 4.4 (4.0 to 4.8)
Bone mass % 4.0 (3.9 to 4.1) 4.2 (4.0 to 4.3) 4.0 (3.9 to 4.1) 4.1 (4.0 to 4.3)
Lean mass (kg)^ 92.2 (89.5 to 94.9) 79.1
a,
* (76.7 to 81.6) 85.3 (82.4 to 88.2) 88.6 (81.7 to 95.5)
Lean mass % 81.8 (81.0 to 82.6) 85.2
a,
* (84.5 to 85.8) 83.4 (82.5 to 84.2) 83.2 (81.6 to 84.9)
Fat mass (kg)^ 16.1 (14.9 to 17.3) 9.9
a,
* (9.2 to 10.7) 13.1 (11.7 to 14.4) 13.8 (10.9 to 17.0)
Fat mass % 14.2 (13.4 to 15.0) 10.7
a,
* (10.0 to 11.4) 12.6 (11.7 to 13.5) 12.6 (10.9 to 14.4)
Notes: BMI, body mass index; LMI, lean mass index.
a
Main effect for position (P< 0.05).
* Large effect size (Cohen’sd>0.8).
^ Age was a significant covariate (P< 0.05).
Table II. Body composition proportional distribution differences using DXA measures according to playing position and ethnicity (mean
(95% confidence intervals)).
Position n= 37 Ethnicity n=37
Forwards n= 20 Backs n= 17 Caucasian n= 27 Polynesian n=10
Arms Lean (kg) 12.7 (12.3 to 13.2) 10.5
b,
* (10.0 to 10.9) 11.5 (11.0 to 12.0) 12.2 (11.1 to 13.3)
Lean % 13.8 (13.5 to 14.1) 13.3 (12.9 to 13.6) 13.5 (13.2 to 13.8) 13.8 (13.5 to 14.2)
Fat (kg) 1.9 (1.7 to 2.0) 1.2
b,
* (1.1 to 1.3) 1.5 (1.4. 1.7) 1.7 (1.4 to 2.0)
Fat % 11.6 (11.0 to 12.1) 12.5
b
(12.1 to 13.0) 11.9 (11.4 to 12.3) 12.4 (11.6 to 13.3)
Legs Lean (kg)
a
32.5 (31.3 to 33.8) 28.0* (27.1 to 29.0) 30.0 (28.9 to 31.0) 31.8 (29.0 to 34.7)
Lean %^
a
35.3 (34.8 to 35.8) 35.4 (34.9 to 35.9) 35.1 (34.7 to 35.5) 35.9* (35.5 to 36.5)
Fat (kg) 6.7 (6.1 to 7.2) 3.8
b,
* (3.5 to 4.1) 5.2 (4.6 to 5.8) 5.7 (4.3 to 7.2)
Fat % 41.2 (39.6 to 42.9) 38.1
b,
* (37.2 to 39.1) 39.5 (38.3 to 40.7) 40.6 (38.2 to 43.1)
Periphery (arms + legs) Lean (kg)
a
45.3 (43.7 to 46.9) 38.5* (37.3 to 39.7) 41.4 (40.0 to 42.9) 44.0 (40.2 to 48.0)
Lean %^ 49.1 (48.4 to 49.7) 48.7 (48.2 to 49.2) 48.6 (48.1 to 49.0) 49.7
c,
* (49.0 to 50.4)
Fat (kg) 8.5 (7.8 to 9.2) 5.0
b,
* (4.6 to 5.4) 6.7 (6.0 to 7.5) 7.4 (5.7 to 9.2)
Fat % 52.8 (51.1 to 54.5) 50.7
b
(49.6 to 51.7) 51.3 (50.2 to 52.5) 53.1
#c
(50.8 to 55.4)
Trunk Lean (kg) 42.7 (41.5 to 44.0) 36.8
b,
* (35.6 to 38.1) 39.9 (38.4 to 41.3) 40.3 (37.4 to 43.2)
Lean % 46.4 (45.8 to 47.0) 46.5 (46.1 to 47.0) 46.8 (46.3 to 47.2) 45.6
c,
* (45.0 to 46.1)
Fat (kg)^ 6.4 (5.8 to 7.0) 3.8
b,
* (3.4 to 4.1) 5.2 (4.6 to 5.8) 5.2 (4.0 to 6.3)
Fat % 39.5 (37.8 to 41.2) 38.1 (36.8 to 39.4) 39.5 (38.2 to 40.8) 37.2
c
(35.3 to 39.1)
Notes:
a
Interaction effect for position. * Ethnicity (P< 0.05).
b
Main effect for position (P< 0.05).
c
Main effect for ethnicity (P< 0.05).
#c
Narrowly missed significance (P= 0.052).
*Large effect size (Cohen’sd> 0.8).
^Age was a significant covariate (P< 0.05).
Head data excluded from table, % distribution values will not add up to 100%.
Body composition of elite rugby union athletes 5
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using DXA between playing positions, with forwards
carrying significantly less fat in their arms than
backs, and significantly more in their legs and total
peripheries (Table II).
While no differences were seen in absolute fat
mass or lean mass using DXA between Caucasians
and Polynesians, significant differences were seen in
the proportional regional distribution of both fat
mass and lean mass using DXA in the periphery
and trunk regions (Table II). No differences were
found in absolute fat mass distribution between
Caucasians and Polynesians using surface anthropo-
metry; however, a large effect size was present when
looking at proportional regional fat mass (Table III).
Discussion
The primary findings of this investigation were that
Caucasian and Polynesian rugby athletes have differ-
ent regional distributions of fat mass and lean mass
in their periphery and trunk regions despite no dif-
ferences in whole body composition being evident.
Regional body composition differences have been
previously reported in non-athletic Polynesian popu-
lations (Rush et al., 2009,2004), and in elite athletic
populations comparing ethnicities other than
Polynesian (Mueller, Shoup, & Malina, 1982;
Sutton, Scott, Wallace, & Reilly, 2009). However,
to our knowledge, this is the first investigation which
has looked at regional body composition differences
using an elite athletic Polynesian population. As has
been previously reported, significant differences
were found in whole body and regional body com-
position between forwards and backs (Duthie et al.,
2003; Higham et al., 2014; Pumpa et al., 2012).
Regional lean mass differences were noted
between ethnicities (Table II), similar to the findings
by Rush et al. (2009) in a non-athletic population.
These differences were related to playing position,
with Polynesian forwards having a greater differential
between lean mass and fat mass in the leg and per-
iphery regions compared with Caucasian forwards.
This differential could provide an advantageous shift
in power to mass ratio, and thus improve an athlete’s
ability to create greater force in explosive movements
including tackles, mauls, scrums, rucks, hits and
sprints. In support of this, research into specific
physique characteristics have found an association
with sprinting performance, including greater gastro-
cnemius lateralis muscle thickness (Kumagai et al.,
2000), and regional skinfold distribution between
the trunk and extremities (Legaz & Eston, 2005).
Future research is warranted to investigate specific
regional body composition traits and their associa-
tion with rugby-specific performance. The findings
of such research could potentially facilitate the devel-
opment of specific training and dietary programmes
to drive training adaptations.
Polynesian rugby athletes were shown to have a
higher proportion of fat mass in their peripheries
and a lower proportion in their trunk when compared
to Caucasian rugby athletes using DXA (Table II). In
a non-athletic population, Rush et al. (2009)also
found Pacific Islanders and Maoris had less fat mass
than Europeans in the abdominal region; however,
they also found less fat mass in the thigh region.
Interestingly, other studies have identified that non-
athletic Polynesians have less fat mass for the equiva-
lent BMI when compared to Caucasians (Craig et al.,
2001;S
winburnetal.,1996,1999), which was not
evident in this elite athletic population (Table I).
The population used in this study is very unique in
nature, all highly trained athletes trying to optimise
physique to meet specific physiological demands. As
differences in body composition distribution
between Caucasians and Polynesians were identified
Table III. Regional body composition differences using surface anthropometry measures according to playing position and ethnicity (mean
(95% confidence intervals)).
Position n= 37 Ethnicity n=37
Forwards n= 20 Backs n= 17 Caucasian n= 27 Polynesian n=10
Arms Skinfolds (mm) 14.0 (12.5 to 15.4) 10.6
a,
* (9.5 to 11.7) 12.5 (11.3 to 13.7) 12.3 (9.8 to 14.8)
Skinfolds % 19.1 (17.8 to 20.4) 21.6
a
(20.5 to 22.7) 20.3 (19.3 to 21.2) 20.1 (17.6 to 22.6)
Legs Skinfolds (mm) 20.3 (18.3 to 22.4) 13.1
a,
* (12.2 to 14.0) 17.9 (15.9 to 19.8) 14.6 (11.8 to 17.5)
Skinfolds %^ 28.1 (25.6 to 30.6) 27.0 (25.2 to 28.8) 29.0 (27.4 to 30.7) 23.7* (21.0 to 26.2)
Periphery (arms + legs) Skinfolds (mm) 34.3 (31.2 to 37.3) 23.7
a,
* (22.0 to 25.4) 30.3 (27.4 to 33.2) 26.9 (22.2 to 31.7)
Skinfolds %^ 47.1 (44.1 to 50.2) 48.6 (46.8 to 50.4) 49.3 (47.4 to 51.1) 43.8* (40.0 to 47.5)
Trunk Skinfolds (mm) 38.8 (34.9 to 42.7) 25.3
a,
* (23.1 to 27.5) 31.6 (28.0 to 35.3) 35.1 (28.5 to 41.8)
Skinfolds %^ 52.9 (49.8 to 55.9) 51.4 (49.6 to 53.3) 50.7 (48.9 to 52.6) 56.2* (52.5 to 60.0)
Notes: Arms –biceps, triceps; legs –mid thigh, medial calf; periphery –biceps, triceps, mid thigh, medial calf; trunk –subscapular,
supraspinale, abdominal.
a
Main effect for position (P< 0.05).
* Large effect size (Cohen’sd> 0.8).
^ Age was a significant covariate (P< 0.05).
6A. J. Zemski et al.
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in this population undertaking the same training, it
could be stipulated the differences are due to genetic
dissimilarities between ethnicities. It is however
recognised that other factors which influence pheno-
type expression (e.g. nutrition) have not been
accounted for or standardised. Interestingly, a
study looking at anthropometric differences between
Polynesian and non-Polynesian junior representative
rugby league athletes found Polynesian players
exhibited advantageous anthropometric attributes
(Cheng et al., 2013). This could be used as further
evidence that Polynesians are predisposed to possess
physical characteristics potentially beneficial to
rugby union performance (Olds, 2001; Sedeaud
et al., 2012), which may be position specific.
Although not statistically significant, a large effect
size was observed when looking at proportional regio-
nal fat mass distribution between ethnicities
(Table III). In contrast to DXA, surface anthropome-
try indicated that Caucasians had a larger proportion
of fat mass in their peripheries (49.3% vs. 43.8%,
P>0.05,d= 1.0) and a smaller proportion in their
trunk (50.7% vs. 56.2%, P>0.05,d=1.0)when
compared to Polynesians. Differences could be as a
consequence of assumptions associated with inferring
whole body composition from a small number of
defined anatomical sites. Alternatively, it could be
due to the fact that surface anthropometry only infers
subcutaneous fat, while DXA is able to assess both
subcutaneous and visceral fat. It could be postulated
that the visceral fat deposition tendencies of
Polynesians are different to that of Caucasians. It
has been identified that racial differences exist in
visceral fat deposition between African Americans
and Caucasians (Conway et al., 1995); however, this
has not been investigated in a Polynesian population.
From a practical perspective, DXA is used less
often in the field than surface anthropometry for
reasons including cost and practicality. As surface
anthropometry does not provide a direct indication
of fat mass, regression equations are often utilised to
estimate this. Given we found inconsistent inferred
regional fat mass distribution using the two assess-
ment techniques, this would provide further evi-
dence to support not using regression equations as
previously advocated by Johnston (1982). However,
the ability of such equations to track changes over
time in elite athletic populations has not been as
widely assessed in the literature (Silva, Fields,
Quitério, & Sardinha, 2009), and to our knowledge
no such studies have taken into account ethnicity.
Whole body composition differences between
playing positions are well documented (Duthie
et al., 2003). As expected forwards were taller, hea-
vier and had a greater sum of seven skinfolds and
lean mass index. They also displayed a greater
amount of absolute fat mass and lean mass in all
body regions compared to backs, supporting pre-
vious research (Higham et al., 2014; Pumpa et al.,
2012). As regional distribution of lean mass has been
identified to influence sprinting performance
(Kumagai et al., 2000), future research into the rela-
tionship between regional body composition and
rugby-specific performance outcomes would be of
interest to sports scientists and coaches.
International representation by foreign-born ath-
letes in rugby is increasing, with 12% of players in
the 1999 World Rugby Cup born in countries out-
side their national squad (Olds, 2001), a trend that
seems to be on the rise based on the sample popula-
tion. This is increasing due to a combination of
international recruitment, increasing ethnic diversity
in developed nations, and the large financial incen-
tives available for playing rugby in certain countries.
It may also be because the evolving physical
demands of the sport may now be better comple-
mented by the intrinsic body composition traits of
Polynesian athletes. For this reason, while the trend
of increasing size in elite rugby athletes continues
(Olds, 2001), and success appears to be closely
linked to size in elite rugby athlete (Olds, 2001;
Sedeaud et al., 2012), it could be speculated that
the proportion of Polynesians participating in rugby
at the elite level will also continue to rise.
The authors recognise this study utilises a relatively
small sample population. However, due to the
Darwinian nature of sport in that only the “fittest”
reach the highest level of participation (Norton &
Olds, 2001), small sample sizes are a reality in
research involving elite athletes. The fact that the
results align closely with both recent research in the
sport (Higham et al., 2014; Pumpa et al., 2012), and
with longitudinal trends (Olds, 2001), suggest the
sample is valid. Despite the Darwinian nature of
sport, there are always going to be exceptions to the
rule and some athletes may not fit the morphological
mould, yet display alternate athletic qualities such as
extreme skill, outstanding physiology and match
instincts which allow them to compete at the elite
level. In this study, three such athletes were identified
as being extreme outliers from the group in terms of
body composition. As these participants were not
typical within the population of interest in relation to
their morphology, they were removed from the statis-
tical analyses. The outliers comprised one Polynesian
back and two Caucasian forwards, who in general
exhibited higher levels of body fat and less relative
lean mass than the remainder of the population.
Conclusion
This up-to-date description of current body compo-
sition characteristics and trends amongst elite rugby
union athletes provides coaches and sport science
Body composition of elite rugby union athletes 7
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staff an indication of what physique traits may be
required for success in international rugby. This
study has identified regional body composition traits
found in Polynesian athletes, which may have the
potential to direct rugby athletes to particular posi-
tions from a body composition perspective.
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