FFor the first aim, we have made progress in the following three areas. 1. We integrated the universal bench-top calibrator for portable accelerometry-based physical activity monitors we developed in 2009 in a study to explain how the digital signal processing filter altered the sensors ability to detect walking at slower speeds. We used both human trials and bench-top testing to confirm our findings, and are in the process of submitting a manuscript. 2. We completed a free-living physical activity and sleep assessment ancillary study to the Age, Gene/Environment Susceptibility-Reykjavik Study (AGES-Reykjavik Study, sponsored by NIA) from March 2009 to July 2010. Using 150 3-axial accelerometers that we optimized in the lab, we successfully collected one week of activity patterns in 660 Icelandic elderly individuals. In 150 of these study participants, we also completed a repeat activity and sleep measurement in an opposite season (Winter vs. Summer). We are currently working with our collaborators in NIA, Iceland Heart Association, and University of Iceland to analyze the activity and sleep characteristics. This is the largest database, to our knowledge, in aging research that would focus on physical activity and cardiovascular health, bone and muscle, metabolism, and cognitive function. 3. We worked with two accelerometer manufacturers to redesign their monitors to incorporate raw acceleration measurements and newly expanded analyses capabilities. With close-collaborations with colleagues in NCI epidemiology branch, we are developing the new objective physical activity measurement standards for the National Health and Nutrition Examination Survey (NHANES 2011-12). For the second aim, we kicked-off the clinical protocol titled Diet-Induced-Obesity Resistant Phenotypes in Humans (09-DK-0238), 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). To date, we have phone-screened 35 potential volunteers (referred either by NIH Patient Recruitment office, flyers, word of mouth, or by direct contact). We consented 8 subjects for outpatient screening. One male subject has completed the protocol, and have two more subjects scheduled for Sept-Oct 2010. We are building a web-based database using the CTDB (NICHD) and plan to increase the recruitment of study participants in the coming year. With the arrival of Dr. Hiroyuki Sasai as the JSPS fellow (visiting scientist), we are preparing a new exercise intervention protocol to study the role of high-intensity interval training vs. traditional aerobic exercise in improving metabolic and cardiac health in obese pre-diabetic patients.