Cross-sectional study of ethnic
differences in physical ﬁtness among
children of South Asian, black African–
Caribbean and white European origin:
the Child Heart and Health Study in
England (CHASE)
C M Nightingale,1,2 A S Donin,1 S R Kerry,1 C G Owen,1 A R Rudnicka,1 S Brage,3
K L Westgate,3 U Ekelund,3,4 D G Cook,1 P H Whincup1
To cite: Nightingale CM,
Donin AS, Kerry SR, et al.
Cross-sectional study of
ethnic differences in physical
fitness among children of
South Asian, black African–
Caribbean and white
European origin: the Child
Heart and Health Study in
England (CHASE). BMJ Open
2016;6:e011131.
doi:10.1136/bmjopen-2016-
011131
▸ Prepublication history and
additional material is
available. To view please visit
the journal (http://dx.doi.org/
10.1136/bmjopen-2016-
011131).
Received 12 January 2016
Revised 6 April 2016
Accepted 13 May 2016
For numbered affiliations see
end of article.
Correspondence to
Dr C M Nightingale;
c.nightingale@sgul.ac.uk
ABSTRACT
Objective: Little is known about levels of physical
fitness in children from different ethnic groups in the
UK. We therefore studied physical fitness in UK
children (aged 9–10 years) of South Asian, black
African–Caribbean and white European origin.
Design: Cross-sectional study.
Setting: Primary schools in the UK.
Participants: 1625 children (aged 9–10 years) of
South Asian, black African–Caribbean and white
European origin in the UK studied between 2006 and
2007.
Outcome measures: A step test assessed
submaximal physical fitness from which estimated VO2
max was derived. Ethnic differences in estimated VO2
max were estimated using multilevel linear regression
allowing for clustering at school level and adjusting for
age, sex and month as fixed effects.
Results: The study response rate was 63%. In
adjusted analyses, boys had higher levels of estimated
VO2 max than girls (mean difference 3.06 mL O2/min/
kg, 95% CI 2.66 to 3.47, p<0.0001). Levels of
estimated VO2 max were lower in South Asians than
those in white Europeans (mean difference −0.79 mL
O2/min/kg, 95% CI −1.41 to −0.18, p=0.01); levels of
estimated VO2 max in black African–Caribbeans were
higher than those in white Europeans (mean difference
0.60 mL O2/min/kg, 95% CI 0.02 to 1.17, p=0.04);
these patterns were similar in boys and girls. The lower
estimated VO2 max in South Asians, compared to white
Europeans, was consistent among Indian, Pakistani
and Bangladeshi children and was attenuated by 78%
after adjustment for objectively measured physical
activity (average daily steps).
Conclusions: South Asian children have lower levels
of physical fitness than white Europeans and black
African–Caribbeans in the UK. This ethnic difference in
physical fitness is at least partly explained by ethnic
differences in physical activity.
INTRODUCTION
In the UK and in other western European
countries, there are marked ethnic differ-
ences in chronic disease risks. British South
Asian adults have increased risks of develop-
ing type 2 diabetes, coronary heart disease
and stroke compared to white Europeans in
the UK.1 2 British black African–Caribbeans,
in contrast, have increased risks of type 2 dia-
betes
and
stroke
compared
to
white
Europeans but lower risks of coronary heart
disease.1
2 Recent evidence suggests that
these ethnic differences in disease risks have
their origins in childhood, with increased
levels
of
insulin
resistance,
circulating
glucose and body fatness in South Asian chil-
dren3
4
and
(to
a
lesser extent)
black
African–Caribbean
children
compared
to
Strengths and limitations of this study
▪ The submaximal fitness test used to predict VO2
max has previously been employed in a nationally
representative sample of the English population.
▪ Ethnic comparisons carried out on a within-
school basis to limit confounding with balanced
representation of South Asians, black African–
Caribbeans and white Europeans.
▪ Objective accelerometer-based levels of physical
activity levels were made using a validated
method and bioelectrical impedance was used to
provide a valid measurement of adiposity in this
multi-ethnic population.
▪ The response rate of 63% was modest and esti-
mated VO2 max was obtained for 75% of the
sample who completed the step test; however,
characteristics of participants with and without
physical fitness data were similar.
Nightingale CM, et al. BMJ Open 2016;6:e011131. doi:10.1136/bmjopen-2016-011131
1
Open Access
Research
white Europeans.4 Marked ethnic differences in physical
activity levels have been reported in the UK in adults5
and children,6 with South Asians in particular having
lower physical activity levels than white Europeans.
However, little is known about the extent of ethnic dif-
ferences in physical ﬁtness, a determinant of cardiovas-
cular and metabolic risk in adults7–9 and children.10 An
earlier report based on a small number of ethnic minor-
ity children studied in the National Study of Health and
Growth raised the possibility that such differences could
be substantial and that they might well be explained by
ethnic differences in physical activity.11 The importance
of independent assessment of physical ﬁtness is empha-
sised by the results of studies, showing that physical
ﬁtness and physical activity are independently associated
with metabolic risk10 and that physical ﬁtness may be a
stronger risk factor than physical activity for coronary
heart disease12 and all-cause mortality.13 We have there-
fore examined ethnic differences in physical ﬁtness in a
study of British school children of South Asian, black
African–Caribbean and white European origin, present-
ing data on the major ethnic groups and subcategories.
We have particularly examined the extent to which
ethnic differences in physical ﬁtness can be explained
by objectively measured physical activity (overall intensity
and moderate to vigorous intensity), an important deter-
minant of physical ﬁtness,10 14 and by adiposity, which is
inversely associated with physical ﬁtness.10
RESEARCH DESIGN AND METHODS
Study design
The Child Heart and Health Study in England (CHASE)
was a cross-sectional investigation of the health (particu-
larly cardiovascular and metabolic health) of primary
school children aged 9–10 years of white European,
South Asian and black African–Caribbean origin in the
UK carried out between October 2004 and February
2007; full details have been published elsewhere.4 6 15
Ethical approval was obtained from the relevant multi-
centre research ethics committee and written, informed
parental consent was obtained for all participating chil-
dren. The study was based in 200 state primary schools in
London, Birmingham and Leicester, half with a high
prevalence of UK South Asian children (stratiﬁed by
Indian, Pakistani and Bangladeshi origin) and other half
with a high prevalence of UK black African–Caribbean
children (stratiﬁed by black African and black Caribbean
origin). Schools were drawn at random from the stratiﬁed
sampling frame; schools which declined to participate
were replaced by another similar school within the sam-
pling frame. This report is based on the ﬁnal phase of
the study (81 schools studied between January 2006 and
February 2007) in which additional assessments of phys-
ical ﬁtness and physical activity were made.
Survey measurements
A single survey team of three trained Research Nurses
and two Research Assistants carried out all assessments;
each observer measured approximately one-third of chil-
dren in each ethnic group. Participating children had
physical measurements including height and weight,
and
arm-to-leg
bioelectrical
impedance,
using
the
Bodystat
1500
bioelectrical
impedance
monitor
(Bodystat, Isle of Man, UK). Fat mass was derived from
impedance using ethnic- and gender-speciﬁc equations
derived for UK children of this age group.16 Fat mass
index (FMI) [fat mass (kg)/height(m)5] was derived to
be independent of height (r=−0.02)16 and was shown to
be a more valid marker of body fatness than body mass
index in this study population.17
Participants underwent an 8-min step test as described
previously.18
19 Brieﬂy, participants were ﬁtted with a
combined
heart
rate
(HR)
and
movement
sensor
(Actiheart, CamNtech, Papworth, UK), then followed an
audible
prompt
instructing
them
to
progressively
increase their step frequency, ramping from 15 to
32.5 body lifts/min (rate of change: 2.5 body lifts/min2)
on a 150 mm high step. The step test was terminated if
the participant was unable to maintain the prescribed
step frequency, even after verbal encouragement from
the investigator. After test termination, 2 min of seated
recovery was measured. The combined sensor-recorded
ECG and acceleration waveforms (128 and 32 Hz sam-
pling, respectively), were summarised in 15 s epochs.
Data were visually reviewed and noisy ECG data were
excluded from analysis. Heart beats were detected using
a modiﬁed Pan-Tompkins peak detection algorithm.18
Estimation of VO2 max was done in a similar manner as
Health Survey for England 2008.20 Brieﬂy, predicted
workload
was
regressed
against
instantaneous
HR
(expressed above resting level) and 1-min recovery HR
was extracted using quadratic regression against recovery
time (ﬁrst 90 s); these parameters were combined with
resting HR and test duration to deﬁne the submaximal
relationship between HR and workload, which was then
extrapolated to predicted maximal HR21 to predict
maximal work capacity. This was converted to VO2 max
by ﬁrst adding an estimate of resting metabolic rate22
and then dividing by the energetic value of oxygen to
estimate.20
Physical activity was assessed by accelerometry; chil-
dren were asked to wear an activity monitor (GT1M;
ActiGraph LLC, Pensacola, Florida, USA), on their left
hip during waking hours (apart from during water-based
activities) for 7 days following measurement and then
return the instrument to the school. The ActiGraph
monitor was worn over the left hip on an elasticised
belt. Non-wear time, deﬁned as periods of at least 20
consecutive minutes of zero counts, was excluded and
remaining
data
were
summarised
into
mean
daily
counts, counts per minute (CPM), steps per day and
time spent at moderate to vigorous intensity (moderate–
vigorous physical activity, MVPA; ≥2000 CPM counts).
All participants with one or more days of valid data were
included in the analysis; a valid day being deﬁned as at
least 600 min of registered time.
2
Nightingale CM, et al. BMJ Open 2016;6:e011131. doi:10.1136/bmjopen-2016-011131
Open Access
Ethnicity and socioeconomic status
The ethnicity of the child was deﬁned using parental infor-
mation on the self-reported ethnicity of both parents
where available (63%), or using the parentally deﬁned
ethnic origin of the child (36%), or using information on
parental and grand-parental place of birth provided by the
child, cross-checked with observer assessment of ethnic
origin (1%). Children were broadly deﬁned (as previously
described4)
as
white
European,
South
Asian,
black
African–Caribbean and other ethnicity; more detailed
ethnic subcategories of South Asians (Indian, Pakistani,
Bangladeshi and South Asian other) and black African–
Caribbeans (black African, black Caribbean and black
other) were also used in analyses. Parents and children
provided information on parental occupation, which was
coded
using
the
National
Statistics-Socioeconomic
Classiﬁcation (NS-SEC) as previously described.23
Statistical methods
Statistical analyses were carried out using Stata/SE soft-
ware (Stata/SE V.12 for Windows; StataCorp LP, College
Station, Texas, USA). Estimated VO2 max was normally dis-
tributed (see online supplementary ﬁgure S1). We used a
previously published regression calibration method to
allow for measurement error in the physical activity vari-
ables (counts, CPM, steps and moderate to vigorous activ-
ity).24 This method allows for within-child variation in
physical activity across a variable number of days of
recording (between 1 and 7) and by day of the week and
provides an unbiased average of counts and CPM for
each child. Most children (87%) had 3 or more full days
of recorded physical activity data. Restricting the analyses
to these children did not materially affect the results.
Gender differences in estimated VO2 max were assessed
using multilevel models adjusted for age, ethnicity and
month of the year (ﬁtted as ﬁxed effects) and school
ﬁtted as a random effect to take account of clustering of
children within schools; all models were ﬁtted using the
xtmixed command in Stata. Similar models were used to
quantify ethnic differences in estimated VO2 max adjusted
for age, sex, month and school. An interaction between
ethnic group and sex was ﬁtted and likelihood ratio tests
were used to examine whether ethnic differences in phys-
ical ﬁtness were modiﬁed by sex. Associations between
estimated VO2 max and physical activity counts, CPM, fat
mass index and resting HR were plotted and were quanti-
ﬁed using correlation coefﬁcients. To examine whether
ethnic differences in estimated VO2 max were explained
by ethnic differences in physical activity, activity counts,
CPM, steps or time spent in moderate to vigorous activity
was ﬁtted as a covariate in the model; fat mass index was
ﬁtted as a covariate to examine whether adiposity
accounted for ethnic differences in estimated VO2 max.
RESULTS
Of 3571 children invited to participate in this phase of
the study, 2236 (63%) took part in the physical ﬁtness
test. Response rates were similar among South Asians
and white Europeans and other ethnic groups (67%,
65% and 63%, respectively) but slightly lower among
black African–Caribbeans (59%); response rates were
higher in girls than boys (66% and 59%, respectively).
Among 2236 children who took part in the test, 73 parti-
cipants were removed from the analysis due to not main-
taining prescribed step frequency during the test and
538
participants
did
not
have
adequate
HR
data.
Estimated VO2
max values were therefore derived for
1625 participants; the proportion of those with valid
physical ﬁtness data was similar in boys and girls and
unrelated to ethnicity, socioeconomic position or phys-
ical characteristics. The children with estimated VO2 max
values included similar numbers of boys and girls (825
and 800, respectively) and similar numbers of children
of
white
European,
South
Asian,
black
African–
Caribbean and other ethnicity (424, 407, 413 and 381,
respectively). Of these children, 1215 also had objective
measures of physical activity.
Unadjusted means and SDs for estimated VO2 max are
shown by gender and ethnic group in online supple-
mentary table S1; adjusted mean levels and gender dif-
ferences in VO2 max are shown in table 1. The overall
level of estimated VO2 max in the study population was
39.4 mL O2/min/kg (95% reference range 30.6, 48.2).
Girls had markedly lower levels of estimated VO2 max
than boys; on average, the level of estimated VO2 max in
girls was 3.06 mL O2/min/kg lower (95% CI 2.66
to 3.47) than that in boys. This gender difference was
apparent in all individual ethnic groups and there was
no strong evidence of an interaction between ethnic
group and sex (p=0.33).
Mean levels of estimated VO2 max for white European,
South
Asian,
black
African–Caribbean
and
‘other’
ethnic groups are presented in table 1 and adjusted dif-
ferences compared to white Europeans are summarised
in table 2. South Asian children had lower levels and
black African–Caribbeans had higher levels of estimated
VO2 max than white Europeans, whereas levels of esti-
mated VO2 max in ‘other ethnicity’ were similar to those
in white Europeans. Within ethnic minority groups,
there was no strong evidence of heterogeneity between
Indian, Pakistani and Bangladeshi children, all of whom
had
lower
estimated
VO2
max
values
than
white
Europeans. Estimated VO2
max levels were higher in
black African–Caribbean children, with the difference
apparently concentrated in boys and black African chil-
dren; the test for heterogeneity between black Africans
and Caribbeans was of borderline statistical signiﬁcance
(p=0.07).
Estimated VO2 max was positively correlated with phys-
ical activity counts, CPM, steps and time spent in MVPA;
correlation coefﬁcients (r) were 0.40, 0.35, 0.34 and 0.37
respectively. Estimated VO2 max was inversely correlated
with resting HR (r=−0.66) and fat mass index (r=−0.37).
As reported previously6 and shown in online supplemen-
tary table S2, physical activity levels (including counts,
Nightingale CM, et al. BMJ Open 2016;6:e011131. doi:10.1136/bmjopen-2016-011131
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Open Access
CPM, steps and MVPA) were lower in South Asians com-
pared to white Europeans; black African–Caribbeans
had similar levels of physical activity (CPM and MVPA),
though mean levels of counts were higher and mean
levels of steps were lower. Adiposity levels (particularly
fat mass index) were previously reported in the larger
CHASE study to be higher among South Asians com-
pared to white Europeans and similar among black
African–Caribbeans compared to white Europeans.17 In
this smaller subset of the CHASE study, fat mass index
was higher in South Asians, though the difference was
not statistically signiﬁcant, and lower in black African–
Caribbeans compared to white Europeans.
The effect of adjustment for physical activity (counts,
CPM, steps or MVPA) and adiposity (fat mass index) on
the overall ethnic differences in physical ﬁtness are pro-
vided in table 3 for the subset of data with measure-
ments of physical activity and adiposity. The higher level
of estimated VO2 max in black African–Caribbean chil-
dren compared to white Europeans was reduced by 25%
when adjusting for objectively measured physical activity
counts; adjustment for steps increased the difference by
34%. Adjustment for fat mass index reduced the differ-
ence in estimated VO2 max by 51% on its own and by
54% in combination with adjustment for physical activity
(table 3). The lower level of estimated VO2 max in South
Asian children compared to white Europeans was not
statistically signiﬁcantly different in this subset; adjust-
ment for objectively measured physical activity further
reduced this difference. For South Asians, adjustment
for fat mass index did not have an appreciable effect on
the ethnic difference in estimated VO2 max either as a
single adjustment or in combination with adjustment for
physical activity (table 3).
In similar analyses, the effects of adjustment for phys-
ical activity and adiposity on gender differences in esti-
mated VO2
max are given in table 3. For all ethnic
groups combined, girls had a markedly lower level of
estimated VO2 max compared to boys; this difference was
reduced by 36% by adjustment for physical activity
Table 2
Ethnic differences in estimated VO2 max (mL O2/min/kg): overall and by sex
Difference in estimated VO2 max (95% CI), p value
Compared to white
Europeans
Boys (n=825)
Girls (n=800)
All
South Asian
−0.69 (−1.51 to 0.14)
0.10
−0.95 (−1.79 to −0.11) 0.03 −0.79 (−1.41 to −0.18) 0.01
Indian
−1.16 (−2.36 to 0.03)
0.06
−1.93 (−3.29 to −0.58) 0.01 −1.52 (−2.45 to −0.59) 0.001
Pakistani
−0.85 (−1.98 to 0.29)
0.14
−0.98 (−2.15 to 0.19)
0.10 −0.90 (−1.75 to −0.05) 0.04
Bangladeshi
−0.15 (−1.48 to 1.19)
0.83
−0.67 (−1.83 to 0.49)
0.26 −0.38 (−1.29 to 0.53)
0.42
Black African–Caribbean
1.03 (0.25 to 1.82)
0.01
0.13 (−0.69 to 0.94)
0.76
0.60 (0.02 to 1.17)
0.04
Black African
1.64 (0.70 to 2.58)
<0.001
0.24 (−0.71 to 1.19)
0.62
0.95 (0.27 to 1.62)
0.01
Black Caribbean
0.10 (−0.99 to 1.18)
0.86
0.17 (−0.96 to 1.29)
0.77
0.14 (−0.65 to 0.93)
0.72
Other
0.31 (−0.50 to 1.11)
0.46
−0.48 (−1.31 to 0.34)
0.25 −0.07 (−0.65 to 0.51)
0.80
Adjusted for sex, age quartiles, month, ethnic group, an interaction between ethnic group and sex (except for analysis of all children
combined) and school (random effect).
Table 1
Adjusted means for estimated VO2 max (mL O2/min/kg) by sex and ethnic group
Mean estimated VO2 max (95% CI)
Ethnic group or subgroup
n
Boys (n=825)
Girls (n=800)
p (sex
difference)
All
p
(ethnicity)*
All children
1625
40.9
(40.5 to 41.3)
37.8
(37.4 to 38.2)
<0.0001
39.4
(39.0 to 39.7)
White European
424
40.7
(40.1 to 41.3)
38.1
(37.5 to 38.8)
<0.0001
39.4
(39.0 to 39.9)
South Asian
407
40.0
(39.4 to 40.7)
37.2
(36.5 to 37.8)
<0.0001
38.6
(38.1 to 39.2)
0.13
Indian
111
39.6
(38.5 to 40.7)
36.2
(35.0 to 37.5)
<0.0001
37.9
(37.1 to 38.8)
Pakistani
147
39.9
(38.9 to 40.9)
37.2
(36.1 to 38.2)
<0.0001
38.6
(37.8 to 39.3)
Bangladeshi
121
40.6
(39.4 to 41.8)
37.5
(36.5 to 38.5)
<0.0001
39.1
(38.2 to 39.9)
Black African–Caribbean
413
41.8
(41.1 to 42.4)
38.3
(37.6 to 38.9)
<0.0001
40.0
(39.6 to 40.5)
0.07
Black African
230
42.4
(41.6 to 43.2)
38.4
(37.6 to 39.2)
<0.0001
40.4
(39.8 to 41.0)
Black Caribbean
148
40.8
(39.9 to 41.8)
38.3
(37.3 to 39.3)
<0.001
39.6
(38.9 to 40.3)
Other
381
41.0
(40.4 to 41.7)
37.7
(37.0 to 38.3)
<0.0001
39.4
(38.9 to 39.9)
Adjusted for age quartiles, month, sex, ethnic group, an interaction between ethnic group and sex (except for analysis of all ethnic groups
combined) and school (random effect).
South Asian other and black other subgroups are not included in the table; therefore, the numbers in the subgroups do not add up to the main
ethnic group totals for South Asians and black African–Caribbeans.
*p Value for heterogeneity between ethnic subgroups within broader ethnic groups, that is, South Asian and black African–Caribbean.
4
Nightingale CM, et al. BMJ Open 2016;6:e011131. doi:10.1136/bmjopen-2016-011131
Open Access
counts, by 28% for CPM, by 30% for steps, by 35% for
moderate to vigorous activity and by 14% for fat mass
index, though the differences were still highly statistically
signiﬁcant. Adjustment for fat mass index in combin-
ation with adjustment for counts or CPM did not appre-
ciably reduce the difference further.
In further analyses, estimated VO2 max did not vary
appreciably by socioeconomic status (NS-SEC), either
overall (p[heterogeneity]=0.08) or within speciﬁc ethnic
groups;
furthermore,
adjustment
for
socioeconomic
status had very little effect on ethnic differences in esti-
mated VO2 max (data available from authors).
DISCUSSION
This study provides evidence of lower levels of physical
ﬁtness in British South Asian children compared with
white Europeans; black African–Caribbean children in
contrast had higher levels of physical ﬁtness compared
to white Europeans. Lower levels of physical ﬁtness were
observed in girls compared to boys; this gender differ-
ence was consistent across all ethnic groups studied. The
lower level of physical ﬁtness in South Asians compared
to white Europeans was at least partly explained by the
lower levels of physical activity in South Asian children.
The higher level of physical ﬁtness in black African–
Caribbeans compared to white Europeans was at least
partly explained by the higher levels of physical activity
and lower levels of adiposity in black African–Caribbean
children. The lower levels of physical ﬁtness observed in
girls could be partly (though not completely) explained
by the lower physical activity levels in girls. Differences
in adiposity did not contribute appreciably to South
Asian–white European or gender differences in physical
ﬁtness.
Relation to previous studies
Levels of estimated VO2 max in boys and girls in the
present study were slightly lower than those in children
aged 10–12 years in a recent small UK-based study25 and
were appreciably lower than those in children aged
9 years in the European Youth Heart Study,26 although
the method of measuring VO2
max differed between
studies; physical activity levels in the present study were
also markedly lower than in the European Youth Heart
Study.6
10 In the present study, girls had appreciably
lower levels of physical ﬁtness compared to boys, this
ﬁnding is consistent with other studies in children of a
similar age group in the UK11 25 and Europe.10 The
ﬁnding that South Asian boys and girls had lower levels
of physical ﬁtness compared to white European children
is consistent with previous ﬁndings in UK adults27 28 and
with a small UK-based study of children aged 9 years;11
that study also reported that levels of physical ﬁtness in
black African–Caribbeans were similar to those of white
European children, consistent with our ﬁndings.11 The
ﬁnding that physical ﬁtness was strongly related to phys-
ical activity in the present study is consistent with ﬁnd-
ings from other studies,10 25 though no previous study
has reported the contribution of physical activity to
ethnic differences in physical ﬁtness.
Strengths and limitations
The submaximal ﬁtness test used in the present study to
predict VO2 max has previously been used in a nationally
representative sample of the English population20 and
has
been
shown
to
capture
two-thirds
of
the
between-individual variance in the submaximal HR-VO2
relationship established using a wider intensity range
during a more well-controlled stress-testing protocol
(treadmill walking and running).19 Average levels and
gender differences in estimated VO2 max were consistent
with those in UK children of a similar age group who
underwent maximal ﬁtness testing.25 The cross-sectional
design of this study means that we cannot infer that the
association we observed between physical ﬁtness and
physical
activity
is
causal;
however,
evidence
from
Table 3
Ethnic and sex differences in estimated VO2 max (mL O2/min/kg): effect of adjustment for physical activity levels and
fat mass index
Difference in estimated VO2 max (95% CI), p value
Adjustments (N=1215)
South Asian–white
European
Black African–Caribbean–
white European
Girls–Boys
Standard
−0.63
(−1.36 to 0.11)
0.09
0.80
(0.14 to 1.46)
0.02
−3.05
(−3.52 to −2.58)
<0.0001
Standard+counts
−0.34
(−1.05 to 0.37)
0.35
0.60
(−0.04 to 1.24)
0.07
−1.96
(−2.47 to −1.45)
<0.0001
Standard+CPM
−0.19
(−0.91 to 0.53)
0.61
0.81
(0.17 to 1.46)
0.01
−2.21
(−2.71 to −1.71)
<0.0001
Standard+steps
−0.14
(−0.87 to 0.59)
0.71
1.07
(0.42 to 1.73)
0.001
−2.12
(−2.64 to −1.60)
<0.0001
Standard+MVPA
−0.22
(−0.95 to 0.50)
0.54
0.72
(0.08 to 1.37)
0.03
−1.99
(−2.51 to −1.46)
<0.0001
Standard+FMI
−0.57
(−1.25 to 0.12)
0.11
0.39
(−0.24 to 1.01)
0.22
−2.61
(−3.05 to −2.16)
<0.0001
Standard+counts+FMI
−0.36
(−1.03 to 0.31)
0.29
0.29
(−0.32 to 0.90)
0.35
−1.87
(−2.36 to −1.39)
<0.0001
Standard+CPM+FMI
−0.26
(−0.95 to 0.42)
0.45
0.44
(−0.18 to 1.05)
0.16
−2.06
(−2.54 to −1.59)
<0.0001
Standard+steps+FMI
−0.19
(−0.88 to 0.49)
0.58
0.63
(0.01 to 1.24)
0.05
−1.92
(−2.41 to −1.42)
<0.0001
Standard+MVPA+FMI
−0.28
(−0.96 to 0.40)
0.42
0.37
(−0.25 to 0.98)
0.24
−1.88
(−2.38 to −1.38)
<0.0001
Analysis carried out in a subset of 1215 children with objective measurements of physical activity.
Standard adjustment is for sex, age quartiles, ethnicity, month and school (random effect).CPM, counts per minute; FMI, fat mass index;
MVPA, moderate to vigorous physical activity.
Nightingale CM, et al. BMJ Open 2016;6:e011131. doi:10.1136/bmjopen-2016-011131
5
Open Access
randomised controlled trials has shown that interven-
tions to increase activity levels in children and adoles-
cents improve physical ﬁtness,29–31 providing support for
this direction of causality. The study included balanced
representation
of
South
Asians,
black
African–
Caribbeans and white Europeans with ethnic compari-
sons carried out on a within-school basis to limit
confounding. Further strengths of this study include the
objective and validated measurement of physical activity
levels using accelerometry32 and the measurement of
adiposity using bioelectrical impedance with ethnic- and
gender-speciﬁc equations for the prediction of fat mass,
a method which has been shown to give more valid
assessment of adiposity in a multi-ethnic population.16
Although the response rate in the study was modest
(63%) and estimated VO2
max was obtained for only
75% of the study sample who completed the step test,
the socio-demographic and anthropometric character-
istics of those participants were similar in those with and
without
physical
ﬁtness
data,
suggesting
that
the
observed ethnic differences in physical ﬁtness are not
likely to be biased.
Implications
The results presented in this study showed that South
Asians had lower levels and black African–Caribbeans
had higher levels of physical ﬁtness compared to white
European children, and that these ethnic differences
were at least partly explained by lower levels of physical
activity among South Asian children and by higher levels
of physical activity and lower levels of adiposity among
black African–Caribbean children. However, ethnic dif-
ferences in physical activity did not appear to provide a
complete explanation for these differences in physical
ﬁtness. Lower levels of physical ﬁtness are associated
with higher levels of adiposity, insulin resistance and car-
diovascular risk.7 10 25 South Asian children have higher
levels of adiposity, insulin resistance and hyperglycaemia,
and black African–Caribbean children and adolescents
have higher levels of insulin resistance and hypergly-
caemia compared to white Europeans.4 The lower levels
of physical ﬁtness among South Asians observed the
present study (by ∼2%) could help to explain the early
development of type 2 diabetes risk among South
Asians; this will be an important area for further investi-
gation. In contrast, the higher levels of ﬁtness observed
in black African–Caribbean children do not help to
explain increased risks of type 2 diabetes in this group.
Improvements in physical ﬁtness (potentially through
increases in physical activity) could be important for
chronic disease prevention in the UK South Asian
population.
Author affiliations
1Population Health Research Institute, St George’s, University of London,
London, UK
2Centre for Primary Care and Public Health, Queen Mary, University of
London, London, UK
3MRC Epidemiology Unit, University of Cambridge School of Clinical
Medicine, Institute of Metabolic Science, Cambridge, UK
4Department of Sport Medicine, Norwegian School of Sport Sciences, Oslo,
Norway
Acknowledgements The authors are grateful to the members of the CHASE
study team (Julie Belbin, Claire Brannagan, Sarah Holloway, Cathy McKay,
Mary McNamara, Miranda Price, Rahat Rafiq, Chloe Runeckles, Lydia
Shepherd and Andrea Wathern) and to all participating schools, pupils and
parents.
Contributors PHW and CMN developed the idea for this paper with help from
CGO, ARR, UE and DGC. PHW conceived, raised funding for and directed
CHASE, with help from DGC, CGO and ARR. ASD collected data. SB, KLW and
SRK derived physical fitness estimates from the results of the submaximal
fitness test with support from UE. CMN and SRK carried out the statistical
analyses. CMN wrote the first draft of the paper. All authors were involved in
interpreting the data, critically reviewing the scientific content and all authors
approved the final version.
Funding This work was supported by grants from the British Heart
Foundation (PG/06/003), Wellcome Trust (068362/Z/02/Z) and the National
Prevention Research Initiative (G0501295). The funding partners for this NPRI
award were: British Heart Foundation; Cancer Research UK; Department of
Health; Diabetes UK; Economic and Social Research Council; Medical
Research Council; Research and Development Office for the Northern Ireland
Health and Social Services; Chief Scientist Office, Scottish Executive Health
Department; and Welsh Assembly Government. Diabetes prevention research
at St George’s, University of London, is supported by the National Institute of
Health Research (NIHR)—Collaboration for Leadership in Applied Health
Research and Care (CLAHRC) South London.
Disclaimer The views expressed in this paper are those of the authors and
not necessarily those of the funding agencies, the National Health Service, the
NIHR or the Department of Health.
Competing interests None declared.
Ethics approval Multicentre Research Ethics Committee, Wales.
Provenance and peer review Not commissioned; externally peer reviewed.
Data sharing statement Enquiries about use of the study data set can be
made by contacting Professor Peter Whincup
Open Access This is an Open Access article distributed in accordance with
the terms of the Creative Commons Attribution (CC BY 4.0) license, which
permits others to distribute, remix, adapt and build upon this work, for
commercial use, provided the original work is properly cited. See: http://
creativecommons.org/licenses/by/4.0/
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Open Access

Cross-sectional study of ethnic differences in physical fitness among children of South Asian, black African-Caribbean and white European origin: the Child Heart and Health Study in England (CHASE).
Nightingale, C M,Donin, A S,Kerry, S R,Owen, C G,Rudnicka, A R,Brage, S,Westgate, K L,Ekelund, U,Cook, D G,Whincup, P H