Can exercise do more harm than good? Mini-heart research is uncovering new answers
"Exercise is medicine" is a commonly quoted phrase. But as is so often the case with medications, more is not always better. What counts as too much exercise, and how can it affect the heart? Does running a marathon or competing in an Ironman triathlon boost your health, or might it do the opposite?

<p>"Exercise is medicine" is a commonly quoted phrase. But as is so often the case with medications, more is not always better. What counts as too much exercise, and how can it affect the heart? Does running a marathon or competing in an Ironman triathlon boost your health, or might it do the opposite?</p>