Youth Energy Expenditure
In 2012, the National Collaborative on Childhood Obesity Research (NCCOR) formed a Youth Energy Expenditure (YEE) workgroup to support research efforts to achieve consensus on methods and measures for establishing youth energy expenditure values. This is important for efforts to reduce childhood obesity because standardized measures to quantify the amount of energy children expend during physical activity have been lacking. These measures are vital for comparing the effects of physical activity interventions and for cost and benefit research.
Until recently, researchers studying children and adolescents have relied on The Compendium of Physical Activities, a resource for values on adults, to translate the energy cost of various physical activities into standardized values. However, the energy costs of physical activity change as children grow and mature, making adult values inappropriate for youth.
In 2008, a Youth Compendium was published but it did not fully meet researchers’ needs because many of its values were based on values from the adult Compendium. NCCOR recognized the importance of filling this gap and, and in 2012 it established the YEE workgroup.
The workgroup’s first task was to convene an expert group, sponsored by the Centers for Disease Control and Prevention (CDC), the National Institutes of Health (NIH), and NCCOR, to discuss the potential impact an updated Compendium could make for both researchers and practitioners. The experts also considered methodological challenges associated with obtaining energy expenditure values that would be derived from data on youth. The executive summary and full report from the meeting are available.
Since then, the workgroup has engaged in several major activities. It has:
- Examined the best metric to use for youth energy expenditure values. The workgroup has conducted several analyses to identify the best energy expenditure metric and determine ways to minimize potential confounders, such as age, sex, and physical characteristics. One analysis was published in PLoS One in June 2015, found that YOUTH-MET was the most feasible metric. A second analysis, published in Pediatric Exercise Science in August 2017, examined measurement error for two methods of accounting for age-related differences in the energy cost of physical activity for children and adolescents—age groups and age by individual year. These methods were compared to a standard value for all ages. The workgroup found that accounting for age showed lower measurement error than the standard value and has used it in the Youth Compendium.
- Conducted a comprehensive literature search. This search was conducted to find newly published data on measured energy expenditure values for youth physical activities. This literature search is nearing completion.
- Published a special issue of the Journal of Physical Activity and Health. To accurately establish values for younger ages, researchers need data on the energy expenditure of children and adolescents performing a wide variety of physical activities. This special issue of the Journal of Physical Activity and Health consists of 17 papers from four countries that provide previously unavailable energy expenditure values on youth from preschoolers to older teens. The papers also include values for nearly 100 separate physical activities, substantially enriching knowledge about activities in which children and youth engage.
- Developed a new Youth Compendium of Physical Activities. The workgroup used three datasets—the pooled dataset from the five research groups, data from the literature review, and the data from the special supplement—and an imputation process to develop the Compendium. The Youth Compendium includes EE values presented in two ways (smoothed and observed/imputed) for 196 activities, including walking, running, and cycling at various speeds. The values are provided for four age groups—6 to 9, 10 to 12, 13 to 15, and 16 to 18.
In October 2017, NCCOR released the new Youth Compendium of Physical Activities on its website. The workgroup also published the data in Medicine & Sports in Exercise & Science in February 2018. The Youth Compendium remains a work in progress, and NCCOR plans to update it over time, as additional data become available.