Sleep trackers use your resting heart rate, heart rate variability and breathing data to estimate how long you sleep and how much time you spend in each stage.

Overview: Heart rate monitors show workout intensity clearly. They help maintain safe and effective training levels.Chest straps offer higher accuracy. Arm ...

View post: JFK Jr.'s Plane Crash & Death: What Went Wrong? Athletes can use performance-enhancing drugs in Olympic-style Las Vegas competition. Event faces criticism; IOC says it "destroys any concept ...