Doctoral Dissertation Research-Estimation of Net Energy Expenditure in Exercising Children: A Simple and Non-Invasive Approach Using Delta HR and Regression Modelling

University Of Washington, Seattle WA

Investigators

Abstract

The importance of research into the assessment of energy expenditure (EE) has increased with the growing awareness of its association with physical activity, obesity, growth and development, health, and work levels. This study focuses on an important, but previously underrepresented group: children. Over the last decade researchers have focused mainly on quantifying EE in adults, but have done little on children, primarily because of the difficulty in assessing EE in children. Artificial environments, invasive techniques, equipment inappropriately sized for children, and lack of tabulated data on activity-specific costs, all contribute to this difficulty. In addition, the costly portable equipment now available is often not affordable. The resultant methodological and informational lacunae call for the development of new methods that will facilitate assessment of EE in children. This study aims to establish an affordable, simple, and non-invasive method for routine estimation of energy expenditure (EE) in children. The project focuses on regression modeling as a means to predict oxygen consumption (VO2)-a proxy of energy expenditure-from heart rate (HR), in conjunction with several easily assessed covariates, for normal children seven to ten years old who live at sea level in a temperate climate. The method used here is innovative, taking as its primary measures the differences between exercise and resting VO2 (DVO2) and between exercise and resting HR (DHR). The reasoning is that DVO2 partially corrects for individual differences in resting metabolic rate and posture, and DHR controls for interindividual variation in physiology and posture. This approach has not heretofore been applied to children. The study will use a repeated measures regression approach based on maximum likelihood estimation. In the process of developing the equation, a set of tests involving specific activities that can be used to create population-specific prediction equations will be established, as well as the range of variation of DEE associated with these activities for children living at sea level in a temperate climate. This method obviates the need for individual calibration between HR and VO2. The principal broader impact of the proposed research is the expansion of knowledge about a particularly underrepresented group- children. Ultimately, this method could serve as a baseline for developing a similar approach for other populations where simple, non-invasive methods for estimating EE are imperative. Such a method, for example, would be ideal in the estimation of EE in children performing subsistence labor in harsh environments. Application of the method will have broad impact across diverse fields like physiology and human biology by allowing a better understanding of children's energetic issues as they relate to obesity, growth, development, and related biocultural parameters.