852. A Youth Compendium of Physical Activities: Activity Codes and Metabolic Intensities
Commentary: Dr Christel van Loo, University of Wollongong, Australia
Physical activity is an established determinant of children’s health. Therefore, the accurate assessment of physical activity energy expenditure is of critical importance for obesity and chronic disease prevention in youth. Accurate measures are essential to establish associations between physical activity and health outcomes, to compare children’s activity levels with physical activity guidelines, and to evaluate the effectiveness of interventions that aim to increase children’s energy expenditure. Measures can be both subjective (e.g. observation, self-report questionnaires) and objective (e.g. accelerometry), though the measurement of physical activity and energy expenditure in children is challenging.
Researchers have used compendia to assign energy costs to observational data when estimating total energy expenditure or time spent in various intensities of activity. Furthermore, compendia can be used to assign energy expenditure data to activities with missing data, or in validation studies of measurement tools in which activities are categorised into physical activity intensities. Though compendia are most commonly used to convert self-report data into energy expenditure, much work has been done to develop compendia on energy expenditure in adults, with little research focused on the energy cost of daily activities in children. Ridley and colleagues developed a Compendium of Energy Expenditures for Youth in 2008 that provided metabolic equivalent values (METs) based on energy expenditure measured in children. Because more than 60% of the values included in the Ridley Compendium were adult-based values, and because considerable additional estimates of physical activity energy expenditure have been published since, an update of the youth compendium is a valuable contribution to the field.
The development of the updated Youth Compendium of Physical Activities consisted of three steps: 1) to decide on the energy expenditure metric that should be used, 2) to perform a comprehensive literature search to find newly published data on measured energy expenditure values for youth physical activities, and 3) a call for researchers to submit unpublished youth energy expenditure data. Various metrics have been evaluated to minimise the influence of age, physical characteristics, and sex on estimates of energy expenditure in youth. As such, Youth-MET (METy: activity energy expenditure divided by the child’s resting energy expenditure) was recommended as the preferred metric, presented in age groups to account for the age-dependency. In 2016, a Supplement was published by the Journal of Physical Activity and Health, containing 17 high-quality studies that measured energy expenditure in children and adolescents while performing specific activities, using indirect calorimetry or whole-room calorimetry. This supplemental issue is unique as it includes data on a wide range of ages and a diverse set of child-specific activities, and contributes to the further development of the Youth Compendium. A summary of these data can be found in the updated Youth Compendium of Physical Activities that presents the METy values for short, discrete age groups (6-9, 10-12, 13-15, and 16-18 years). The Youth Compendium consists of METy values per age group for 196 specific activities, of which 51% were measured and 49% were imputed data from children and adolescents.
The updated Youth Compendium of Physical Activities will support investigators to code physical activities by type and intensity in a standardised system across studies of children and adolescents.
Source: Medicine & Science in Sports & Exercise Published Ahead of Print. Access to this article may depend on your Institutional rights: Access the full article here.