Accelerometers for measuring physical activity behavior in Indian children

Krishnaveni, G.V., Mills, I.C., Veena, S.R., Wootton, S.A., Wills, A.K., Coakley, P.J., Fisher, D.J., Shobha, S., Karat, S.C. and Fall, C.H.D. (2009) Accelerometers for measuring physical activity behavior in Indian children. Indian pediatrics, 46 (12), 1055-1062.

Abstract

Objective: To examine the validity of accelerometers for
characterizing habitual physical activity patterns in Indian
children.

Design: Cohort study.

Setting: Holdsworth Memorial Hospital, Mysore.

Subjects: Children (N=103, mean age 6.6 years) selected
from an ongoing birth cohort study.

Methods: Physical activity was measured over 7 days
using accelerometers (MTI Actigraph) and concurrent
parent-maintained activity diaries. Actigraph counts per
minute representing sedentary (<10), light (<400),
moderate (<3000) and vigorous (?3000) activity were
determined using a structured activity session in a
separate group of 10 children. In 46 children chosen for
validating accelerometers, time spent in different activity
levels according to diaries was determined. Energy
Expenditure (EE) was calculated from diaries using a
factorial method.

Results: Ninety-eight children wore the monitor for ?4
days. Total counts and time spent in different activity levels
were similar in boys and girls (P>0.2). Among 46 children
chosen for comparisons, time spent in sedentary (r =0.48,
P=0.001), light (r=0.70, P<0.001) and moderate activities
(r=0.29, P=0.054) according to diaries correlated with
those derived from counts, and total Actigraph counts
correlated with EE (r=0.42, P=0.004). Bland-Altman
analysis showed systematic bias, and wide limits of
agreement between these methods for time spent in
different activity levels.

Conclusions: Accelerometers are a well tolerated and
objective way of measuring activity behavior in free-living
children. Though accelerometer counts correlate with time
spent in activity of varying intensity and energy
expenditure derived from parent-maintained diaries, wide
limits of agreement show that the limitations of
accelerometers need to be recognized in interpreting the
data that they generate.

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Contributors

Author: C.H.D. Fall

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