Blood pressure changes vary with the type of exercise. Aerobic exercise, such as running, swimming or bicycling, increases the heart rate and generally increases the pressure with which blood is pumped, thus raising the systolic number. The diastolic pressure normally remains stable. This is the preferred exercise for the heart. Static or isometric exercise, such as weightlifting, requires sustained muscle contraction with little or no increase in cardiac output; the result is a rise in both blood pressures. Isometrics have shown some beneficial long-term lowering of pressures, however.