Exercise is an important part of a healthy lifestyle. But in individuals with heart troubles, too much exercise can be a bad thing too -- it can speed up heart failure ... in rats, at least. These findings are in direct opposition to what researchers thought they would find -- that the more they exercised, the healthier rats are. But don't use these findings as an excuse to skip the gym for the next few decades -- it's still thought that a reasonable amount of exercise is better than a sedentary lifestyle. Excessive exercise might be a problem, but a daily walk will not kill you.
