Medically reviewed by Rafle Fernandez, MD Key Takeaways A fast heartbeat can be caused by emotions like stress or anxiety.Dehydration, or drinking caffeine or other stimulants, can make your heart ...

Breathlessness, swollen ankles and unusual tiredness can be signs that the heart is struggling to meet the body’s needs.

From resting heart rate to training zones to heart rate variability, heart rate data gets a lot of glory when it comes to running—and for good reason! But now, some athletes are starting to talk about ...

The heart is the body's hardest-working muscle. Whether you're awake or asleep, or exercising or resting, your heart is always at work. It pumps blood through arteries to deliver oxygen to organs and ...

Sympathetic is a free iPhone app that pairs guided slow breathing with live heart rate, HRV and ECG from a Polar H10, so ...