Body composition. Dual Energy X-ray Absorptiometry (iDXA, GE Medical Systems, Madison, WI; located in the Health and Exercise Science Department, WFU). Whole body scans will be acquired with the participant supine and aligned with the scanner table as prescribed by the manufacturer. DXA will also be used to analyze bone mineral density (BMD) using specific scans of the anterior-posterior (AP) spine (L1-L4) and proximal femur. Coefficients of variation (CV) from repeated measurements are 1.0% for lumbar spine BMD and 1.0% for femur BMD. All scans will be performed and analyzed by our trained DXA technician who is certified by the International Society for Clinical Densitometry and has vast experience in body composition measurements in older adults. Every scan will be examined to evaluate for proper patient positioning and analysis, and reanalysis or rescanning will be performed if necessary. Any artifacts will be noted and, if possible, excluded from the measured region. Daily quality control scans are obtained with GE's phantoms.