For the first aim, we continue to refine the three large-size whole-room indirect calorimetry suites (commissioned in 2008). In addition to robust 24-hr energy expenditure and macronutrient oxidation measurements, we made considerable improvements in measurement accuracy and sensitivity using a wavelet-based de-noising algorithm. We also designed and implemented new sampling, filtering, and calibration systems for all three suites to prolong system longevity, reduce measurement errors and artifacts, and improve operational efficiency. These were the work we laid out to accomplish from FY2008. For free-living activity assessments, we successfully developed a universal bench-top calibrator for portable accelerometry-based physical activity monitors. With this apparatus, we can comprehensively study the variability between and within monitors of various size, sensitivity, accuracy, and ranges. For the second aim, we developed a new clinical protocol titled Diet-Induced-Obesity Resistant Phenotypes in Humans, with the goal of identifying healthy lean subjects who are resistant to hypercaloric diets and studying their unique compensatory mechanisms for achieving energy and weight balance under 4 weeks of overfeeding (+1000 kcal/day over weight balanced diets). This protocol was approved by the IRB in August 2009 and will start accruing study participants in Oct 2009. We also launched a free-living physical activity and sleep assessment ancillary study to the Age, Gene/Environment Susceptibility-Reykjavik Study (AGES-Reykjavik Study, sponsored by NIA) in March 2009. Using 100 sophisticated 3D accelerometers that we optimized in the lab, we are in the process to collect one week of activity patterns in 1000 Icelandic elderly individuals. We expected that the activity characteristics measured by the accelerometers would complement the focus on cardiovascular health, bone and muscle, metabolism, and cognitive function in this unique population.
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