A. PROJECT SUMMARY Skeletal muscle is the most abundant insulin-sensitive tissue in the body making it an important organ system in the prevention of cardiometabolic disease. Resistance training is the physical activity modality that directly increases muscle hypertrophy and in doing so increases GLUT4 expression. GLUT4 is an insulin-regulated glucose transporter with the primary role of stimulating glucose uptake; therefore, hypertrophy leads to increased insulin sensitivity. Resistance training and enhanced insulin sensitivity have the potential to lower the burden of cardiovascular and metabolic disease. However, what we know about the role of resistance training on long-term health outcomes is limited by the blunt tools currently used to measure resistance training in longitudinal epidemiologic studies. Progress in the physical activity epidemiology field is limited because resistance training volume is not measured in population studies with the same level of precision as aerobic activity and as a result, we do not know the optimal balance of movements to promote health across the life course. The objective of the proposed research is to ameliorate the gap in assessing resistance training volume at an epidemiological level and assess how resistance training volume affects cardiovascular and metabolic disease independently and jointly with aerobic activity. The training will enable the scientific objectives of this application, which are to evaluate the independent and joint associations of resistance training with estimates of insulin resistance and blood pressure. This award will provide Dr. Booker with added training in 1) survey development, 2) resistance training, 3) cohort development, and 4) biostatistics. Training will take place at Northwestern University Feinberg School of Medicine, supported by a strong team of mentors from multiple peer institutions with expertise in each of these areas. In the K99 phase, Dr. Booker will develop and validate an epidemiological instrument to collect resistance training volume (Aim 1) and identify the age group where the instrument performs the best. During the R00 phase, Dr. Booker will use the instrument to determine the association of resistance training volume with estimates of insulin resistance and blood pressure (Aim 2). He will then determine the optimal ratio of movement behaviors for estimates of insulin resistance and blood pressure (Aim 3). The proposed training and research will propel Dr. Booker towards successfully achieving his long-term research goal of developing tailored physical activity training programs to promote ideal cardiovascular and metabolic health. Resistance training has emerged among the top fitness trends worldwide and has the potential to serve as another tool to lower the burden of cardiovascular and metabolic diseases.