Measurement of physical activity and energy expenditure using heart rate, motion sensors and questionnaires

This dissertation was designed to examine new techniques to measure physical activity (PA) and energy expenditure (EE) during lifestyle activities. The specific aims were: 1) to evaluate heart rate (HR), using percent of HR reserve in relation to percent of oxygen uptake reserve, as a method for assessing moderate intensity PA in the field setting; 2) to validate the simultaneous heart rate-motion sensor (HR+M) technique to estimate EE of selected activities; 3) to validate the simultaneous HR +M technique to predict EE over an extended time period; and 4) to use the simultaneous HR+M technique to validate selected PA questionnaires over a 7-day period. For the first aim, sixty-one males performed physical tasks in both a laboratory and field setting. HR and oxygen uptake (V0 2) were continuously measured during 15- min tasks. HR data was used to predict EE using age-predicted maximum HR and estimated maximal V0 2. The correlation between HR and measured V0 2 was r=0.68. After adjusting for age and fitness level, HR provided an accurate estimate of EE, r=0.87. Using percent HR reserve to estimate percent V02 reserve significantly improved the estimation of EE.