Methodology of physical-activity and energy-expenditure assessment: a review

Over the last decades, substantial epidemiological evidence has been accumulated on the protective role of increased physical activity (PA) for the prevention and management of certain chronic diseases. To better address the impact of physical activity on health, valid and reliable instruments for its measurement are essential. Because of its dimensionality, a large number of methods exist for the assessment of various aspects of physical activity. This review provides a summary of available tools for measuring physical activity and total energy expenditure (TEE) and addresses their advantages and limitations in assessing PA in epidemiological surveys. The selection of the appropriate method for a specific survey should be based on criteria such as experimental goals, sample size, budget, cultural and social/environmental factors, physical burden for the subject, and statistical factors such as validity and reliability. The instruments that are very precise in measuring total energy expenditure such as doubly-labeled water method and direct and indirect calorimetry tend to be impractical on a population basis. On the other hand, methods such as self-report techniques are applicable for epidemiological studies, but they lack accuracy in measuring energy expenditure (EE).