The available literature on physical activity (PA) and fitness in adolescents contains no studies on Vietnamese subjects. Given that habitual PA in adolescents is
shaped by cultural and environmental context, such a study is necessary to establish a comprehensive understanding of PA and fitness in adolescents. To date no measure of PA suitable for use with the Vietnamese adolescent population has been developed and no study on the PA levels of Vietnamese adolescents and appropriate correlates has been undertaken. The studies contained in this dissertation developed a method for estimating energy expenditure (EE) in such a population and revealed the determinants of PA for Vietnamese adolescents.