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Indian Pediatr 2009;46: 1053-1054 |
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Physical Activity Assessment With
Accelerometers in Children |
Klaas R Westerterp
Department of Human Biology, Maastricht University, PO
Box 616, 6200 MD Maastricht, The Netherlands.
Email: [email protected]
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Accelerometers for movement registration
have the potential to reflect the volume, pattern, intensity, type, and
energy expenditure of physical activity(1,2). Developments are still
ongoing with regard to reduction of the size of the instruments,
lengthening of battery life and translation of the output to meaningful
information for the user. Instruments with the capacity for most or all
functions mentioned are tri-axial and mounted on a waist belt.
Krishnaveni, et al.(3) measured physical
activity in children with uni-axial accelerometers (MTI Actigraph AM7164,
MTI Health Services, Florida, USA). Time spent in sedentary-, light-,
moderate- and vigorous intensity activity, as calculated with self-defined
cut-off levels for accelerometer counts, was compared with simultaneously
kept diaries of the child’s activities by parents and teachers. The wide
limits of agreement between accelerometer-assessed and diary-assessed time
spent in activities of varying intensity was seen as a limitation of the
data accelerometers generate.
One can argue on the conclusion derived from the data
as stated by the authors. The interrelation of accelerometers with diaries
may be of some value, but because there are potentially errors in both
methods, it is impossible to determine the true validity of any one of
them in doing so. Calorimetry, more specifically the doubly labeled water
method, has become the gold standard for the validation of field methods
of assessing physical activity(4). Then, accelerometers show a high
potential as a field method for the assessment of volume, pattern,
intensity, type, and energy expenditure of physical activity.
The conclusion as derived by Krishnaveni, et al.(3)
generalizes the results as derived with one type of uni-axial
accelerometer (MTI Actigraph AM7164, MTI Health Services, Florida, USA) to
accelerometers in general. However, the capacity of accelerometers to
assess physical activity dimensions like volume, pattern, intensity, type,
and energy expenditure of physical activity is a function of the
characteristics of the sensor and the data processing. Again, doubly
labeled water is the indicated reference for evaluation. Thus, it appeared
using a tri-axial instead of a uni-axial accelerometer impro-ved the
performance significantly(5).
The study by Krishnaveni, et al.(3) shows modest
relations between Actigraphs and diaries for time spent in sedentary-,
light-, moderate intensity activity, but not for vigorous intensity
activity. Future evaluations on physical activity assessment in children
should specifically focus on the capacity to detect high-intensity
activity. Hoos, et al.(6) did a study on physical activity in
similar aged children with a tri-axial accelerometer, showing that to
obtain a higher physical activity level in children, they should be given
opportunities to perform high-intensity activities.
Funding: None.
Competing interests: None stated.
References
1. Bonomi AG, Goris AHC, Yin B, Westerterp KR.
Detection of type, duration and intensity of physical activity using one
tri-axial accelerometer. Med Sci Sports Exerc 2009; 41: 1770-1777.
2. Van Hees VT, van Lummel RC, Westerterp KR. Validity
of a seismic accelerometer for estimating energy expenditure under
sedentary conditions. Obesity 2009; March 12, Epub ahead of print.
3. Krishnaveli GV, Mills IC, Veena SR, Wootton SA,
Wills AK, Coakley PJ, et al. Accelerometers for measuring physical
activity behavior in Indian children. Indian Pediatr 2009; 46: 1055-1062.
4. Westerterp KR. Assessment of physical activity: a
critical appraisal. Eur J Appl Physiol 2009; 105: 823-828.
5. Plasqui G, Joosen AMCP, Kester AD, Goris AHC,
Westerterp KR. Measuring free-living energy expenditure and physical
activity with tri-axial accelerometry. Obes Res 2005; 13: 1363-1369.
6. Hoos MB, Kuipers H, Gerver WJM, Westerterp KR.
Physical activity pattern of children assessed by tri-axial accelerometry.
Eur J Clin Nutr 2004; 58: 1425-1428.
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