Before you begin to exercise, you can easily determine your target heart rate by following these three steps:
1) Subtract your age from 220. If you are 50, your maximum heart rate is
170.
Example: 220 – 50 = 170
2) Multiply your maximum heart rate by 0.55 to obtain the bottom of your
target zone.
Example: 170 x 0.55 = 93
3) Multiply your maximum heart rate by 0.65 to obtain the top of your
target zone.
Example: 170 x 0.65 = 110