Getting into an optimum heart beat zone is vital if you want to reap the full benefits of your exercise, a new study reveals.

MHR is calculated roughly as 220 heart beats per minute minus a person’s age. The researchers said that the full benefits of regular exercise can only be reaped if a person reaches at least 50 percent of his MHR.
“Exercisers need to get to at least a moderate level of physical activity in order to reap the benefits. Your goal is to get to a stage where you're fit enough to exercise within your heart rate training zone. It's not exact but it doesn't need to be. It's a really good indicator”, lead researcher Dr Adrian Hutber said.
Source-Medindia