The following information and study published in the journal Hypertension and referenced in Best Life magazine backs up a lot of this general thought process:
"While exercise can decrease heart disease risk, if you're one of the 72 million American's with high blood pressure, there's a fine line as to how hard you should push yourself. A recent study, published in the journal Hypertension, found that excessive exercise causes structural abnormalities in the hearts of those with high blood pressure-aberrations such as enlarged hearts and decreased pumping ability. Your doctor can tell you how much exercise is too much."
From my perspective though no matter what your health is exercise is a good thing and it should be practiced even if at a very low intensity. At the very least it is good for the mood and for treating depression.
Best Life, Dec '07