Impact of Physical Activity on Left Ventricular Mass and Lipid Metabolism

Left ventricular hypertrophy, defined as an increase in the mass of the left ventricle may occur as a physiologic response to exercise (athletic remodeling aka "athletic heart"), but is most frequently encountered as a pathological manifestation of cardiovascular disease. The early determinants of athletic remodeling in the general population are largely unknown. In order to longitudinally explore the early determinants of athletic remodeling, we will recruit from the community, physically untrained women who have volunteered to run a marathon. We will prospectively assess left ventricular mass and function by echocardiogram during three consecutive stages/visits: * Baseline: prior to starting intense physical training * Trained: at the end of at least 12 week training period, prior to running the marathon. * Post-marathon: 6 weeks after running the marathon. In addition, exercise impacts lipid metabolism and short-term exercise is known to increase HDL levels in plasma. Human HDL is structurally heterogeneous, comprising at least sixteen discrete species. It has multiple functions, pertinent to cardiovascular medicine such as the ability to accept effluxed cholesterol from the artery wall, culminating in sterol uptake in the liver. This "reverse cholesterol transport pathway" is thought to prevent the accumulation of cholesterol in the artery wall. We will assess the clinical and genetic determinants of the HDL response to physical exercise.