CARDIOVASCULAR JOURNAL OF AFRICA • Vol 21, No 6, November/December 2010
Cardiovascular Topics
316
AFRICA
Significant differences between serum CRP levels in
children in different categories of physical activity:
the PLAY study
B HARMSE, HS KRUGER
Summary
Low-grade systemic inflammation is emerging as a compo-
nent of the metabolic syndrome. The purpose of this study
was to assess the association between serum C-reactive
protein (CRP), physical activity and body composition in
193 black children aged 13 to 18 years from a South African
township. Demographic information and anthropometric
measurements were taken, and fasting blood samples were
analysed for high-sensitivity serum CRP. Body fat was meas-
ured by air displacement plethysmography.
There was a trend towards higher serum CRP in the boys
with a higher percentage body fat. After multiple regression
analyses, waist circumference in the girls was significantly
associated with serum CRP. In the boys, there was an inverse
correlation between percentage body fat and fitness, and
between fitness and serum CRP. Significant differences were
found between serum CRP in the different physical activity
categories, with lower serum CRP in the girls in the higher
physical activity group. Obesity should be prevented in
SouthAfrican children by encouraging physical activity.
Keywords:
C-reactive protein, inflammation, physical activity,
adolescent, metabolic syndrome, body composition
Submitted 2/3/09, accepted 10/3/10
Cardiovasc J Afr
2010;
21
: 316–322
Obesity is currently the most common and costly nutritional
problem in developed countries,
1
with 10% of the world’s
school-aged children estimated to be overweight.
2
The preva-
lence of overweight is rising significantly in most parts of the
world, especially in economically developed regions. This rapid
increase implicates environmental rather than genetic factors,
2
although one cannot exclude the interaction between genes and
the environment.
3
The metabolic syndrome (MS), a cluster of five biological
markers that together predict the development of cardiovascu-
lar disease and type 2 diabetes, is now increasingly emerging
among children and adolescents.
4
These markers are hyperten-
sion, insulin resistance, central adiposity, hypertriglyceridaemia
and decreased high-density lipoprotein cholesterol. Low-grade
systemic inflammation is increasingly being observed as a
significant component of the MS.
5
Various cytokines and chemi-
cal messengers, which induce their effects individually or in
interaction with each other, constitute the main regulators of the
inflammatory process.
5
Young people in lower-income families are particularly
vulnerable to obesity because of poor diet and limited opportuni-
ties for physical activity. In developing countries, obesity among
the youth is most prevalent in wealthier sections of the popula-
tion, but it is also rising among the urban poor in these countries,
possibly due to their exposure to westernised diets, coinciding
with a history of under-nutrition.
2
Lobstein
et al.
2
emphasised
that children from socio-economically deprived environments in
most western societies have a greater risk of obesity than chil-
dren from more affluent groups.
Adolescence is an important period during development,
and significant somatic growth and maturation are evident
during this time. The pubertal growth spurt is associated with
significant changes in body composition, where girls tend to
accumulate more fat than boys.
4
Adolescence is one of the
most vulnerable periods for the development of overweight and
obesity.
2
Although the mechanism is unclear, it is possible that fat
distribution patterns established during adolescence play a role.
2
The maximum body mass index attained at post-pubescence is
strongly associated with the degree of fatness in adulthood.
3
South Africa is a developing country with both under- and
over-nutrition. The prevalence of obesity is high among black
women, whereas it is low in children.
6
Stunting is a very common
nutritional disorder in South Africa and local research has shown
that there may be a link between stunting and the development
of overweight or obesity.
7
According to Monyeki
et al
.,
8
obesity
is not only common in South African women, but also in female
adolescents. In 2002 the first South African National Youth Risk
Behaviour survey stated that the prevalence of overweight among
secondary school learners was 17% and obesity 4%.
9
These data
also showed that the co-existence of stunting and being over-
weight is a public health problem among adolescents in South
Africa.
9
Obesity during childhood seems to increase the risk of subse-
quent morbidity, whether obesity persists into adulthood or not,
with obese children being at an increased risk of metabolic and
cardiovascular disorders later in life.
10
Recent South African
studies indicate that measures of overweight were positively
School of Physiology, Nutrition and Consumer Science,
North-West University, Potchefstroom, South Africa
BERNA HARMSE, MSc
H SALOME KRUGER, PhD,
