title: I hear a lot about how exercise is good for the heart, but I've never heard anything about why it works. How does exercise help? And do I have to work out every day?
mesh_terms: D001794:Blood Pressure / Q000502:physiology; D015444:Exercise / Q000502:physiology*; D006321:Heart / Q000502:physiology*; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D013997:Time Factors