| Summary: | Dissertation (Ph.D.) University of Alaska Fairbanks, 2013 Being active and preventing excess body fat are important for maintaining good health. The ability to measure activity and body composition accurately is important to understanding the role of activity and adiposity in health. This dissertation highlights key findings regarding assessment tools for physical activity and body composition and the associations between physical activity and body composition with health in Yup'ik people. The main objectives of this dissertation were to: l) assess the accuracy of bioimpedance and multiple regression models from anthropometry for estimating body composition (fat mass, fat-free mass, and percent body fat) as compared with doubly-labeled water (DLW) body composition estimates, 2) determined the associations between body size estimates, including simple anthropometry and body composition estimates, and obesity-related health risk factors and disease outcomes, 3) assess the accuracy of a combined heart rate/movement monitor (Actiheart) for determining physical activity energy expenditure (PAEE) as compared with DLW PAEE, and 4) determine the associations between physical activity subcomponents and obesity-related health risk factors in Yup'ik people in southwestern Alaska. Body composition can accurately be estimated using only three variables -sex, waist circumference (WC), and hip circumference with a multiple R 2=0.9730 with DLW fat mass. WC and other anthropometries were more highly correlated with a number of obesity-related risk factors than were direct estimates of body composition. When determining the accuracy of the Actiheart for determining PAEE as compared with DLW PAEE, none of the software PAEE models investigated were significantly correlated with DLW PAEE (ranging from r=0.02 {95% e1 (-0.38, 0.41) to r=0.22 {-0.20, 0.56)). Limits of agreement (mean difference +/- 1.9650) for all software models were large, ranging from ---4540 to 1600 kcal/day. The best correlate of DLW PAEE from the Actiheart was ...
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