What is box breathing? The deep breathing technique is one of the ways to calm down and lower heart rate fast, cardiologists say.

In TODAY.com's Expert Tip of the Day, a cardiologist explains why a lower resting heart rate can be a good sign of heart ...

From Apple Watches to Fitbits to treadmills, there are more ways than ever for people to keep up with their vitals. So why does so much fitness tech check your pulse? Because your resting heart rate ...