Influence of physical activity, sedentary lifestyle and bone biomarkers on bone health among adolescents in Kota Bharu, Kelantan
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Date
2013-05
Authors
Teo, Pey Sze
Journal Title
Journal ISSN
Volume Title
Publisher
Universiti Sains Malaysia
Abstract
Maximum attainment of peak bone mass (PBM) during the growing years is
ultimately important to reduce the risk of osteoporotic fracture later in life.
Understanding and identification of lifestyle factors such as physical activity (PA)
and other lifestyle practices that are associated with higher bone mass accruals in
children and adolescents is important in order to optimize the PBM during these
critical years of growth. Therefore, the main objective of the study was to determine
the influence of PA, sedentary behavioural practice and blood biomarkers of bone
remodeling on bone health status, as assessed by a dual energy X-ray absorptiometry
(DXA) in 455 adolescent boys and girls of Malay and Chinese-origins aged 12 to 19
years of age in Kota Bharu, Kelantan. Validated questionnaires were used to assess
PA, sedentary small screen recreation (SSR) practice assessments, and dietary food
intakes, whereas body composition and muscular strength of the upper and lower
extremities were determined using anthropometry measurements, handgrip and
isokinetic-dynamometers. For the bone health status, bone mineral content (BMC),
bone area (BA) and bone mineral density (BMD) were assessed for total body (TB),
at the lumbar spine (L2-L4), proximal femur and specific regions of interest using
the DXA device. Mean age of the adolescents were 15.4 1.9 years, with majority
(72.5%) had a normal ranges of body mass index (BMI). Sex-specific comparisons
on lifestyle practices showed that adolescent boys had significantly higher levels of
daily PA status (1.5hours vs. 1.0hours; P<0.001) and intense moderate-to-vigorous
PA (MVPA) (1.2 vs. 0.4hours; all, P<0.001), compared to the girl participants. In
contrast, sedentary SSR practices were similar between genders (3.1 vs.
3.3hours/day). In general, about two-thirds of adolescents (63.3%) had low daily
active PA practice, as determined by the MVPA less than one hour per day, with
higher proportion found in girls (80%) than in adolescent boys (34%). Multiple linear
regression analyses showed that age (P=0.012) and sex (P<0.001) emerged as
significant negative determinants on daily MVPA levels, after adjusting for ethnicity,
socio-demographic status and dietary behaviours. Moreover, age (P<0.001) and daily
breakfast consumption (P<0.05) emerged as negative independent determinants;
whereas ethnicity (P<0.01) was significant positive independent determinant on
sedentary SSR levels. The influence of these lifestyle factors was further examined
based on duration spent on PA levels and sedentary SSR levels. It showed that
participant boys with higher total PA group>1.5hours/day and MVPA
group>1hour/day, respectively, had a significantly higher size-adjusted BMC of TB,
intertrochanter and leg region (all, P<0.05) and the BMD of the TB, PF, LS, regional
arm and leg region (at least, P<0.01) than that of those at low PA and MVPA levels.
Only a significant positive influence was found between high total PA and MVPA
with BMC and BMD of the TB and leg region in adolescent girls. Furthermore, boys
with high MVPA levels showed significantly higher of muscle strength of the
handgrip (P<0.01) and lower extremity strength of the quadriceps (P<0.05) and the
hamstring strength (P<0.001) than those at lowest MVPA level. Only a significant
positive association was found between high MVPA level and hamstring muscle
strength in girls (P<0.01). On the other hand, sedentary lifestyle practices was also
found to be negatively associated with bone health profiles assessed in girls, in which
high SSR practice showed a significantly lower lumbar spine BMD (P<0.05) and
bone area of the TB (P<0.05), arm (P<0.01) and leg region (P<0.05) compared to
those who only practiced low SSR level. Blood biomarkers of bone remodeling were
significantly and negatively associated with all skeletal sites assessed, after
adjustments for pubertal growth and ethnicity. These present results showed that
higher habitual total and intense PA level could contributed to positive bone mass
profiles in these adolescents, and it has profoundly influence on weight-loaded
skeletal region assessed. In addition, sedentary lifestyle practices also exert a
negative influence on bone health assessed in adolescent girls. Therefore,
encouragement of active lifestyle practices in children and adolescents should be
promoted to optimize the peak bone mass accretion during the critical years of
growth.
Description
Keywords
Bone