Aerobic exercises like swimming, jogging and cycling raise the heart rate. "The goal is to raise and sustain that elevated heart rate in what we call a training heart rate zone," said Dr. Jonathan Whiteson , medical director for cardiac rehabilitation at NYU Langone Medical Center. Most people can calculate a ballpark maximum heart rate by subtracting their age from 220, said Whiteson. At 55, Murphy said his heart rate follows that trend to a T, peaking around 165. In 2009, Mayo Clinic began recommending HIIT to people who had been diagnosed with heart attack or heart failure.

Source: CNN February 24, 2017 15:10 UTC