Heart Valve Leakage And Exercise

At 78 years old, I am in pretty good shape. A couple of years ago, an echocardiogram showed a small leak in my mitral valve. A year later, a follow-up test showed some leakage in my tricuspid valve. The valves aren?t causing me any problems right now, but how will I know if they need to be repaired? I like to exercise, but don?t want to make these valve problems worse. Is it okay for me to walk on a treadmill at a speed of 3 to 4 miles an hour and lift light weights?