There are several ways to determine your target heart rate. One of the simplest is this: maximum heart rate (220 - age) x 70%. Thus, the target heart rate for a 40 year-old would be 126.
Some methods for figuring your target rate take individual differences into consideration. Here is one of them:
- Subtract age from 220 to find maximum heart rate.
- Subtract resting heart rate (see below) from maximum heart rate to determine heart rate reserve.
- Take 70% of heart rate reserve to determine heart rate raise.
- Add heart rate raise to resting heart rate to find target rate.
Your resting heart rate should be determined by taking your pulse after sitting quietly for five minutes.
When checking your heart rate during a workout, take your pulse within five seconds after interrupting exercise because it starts to go down once you stop moving. Count your pulse for 10 seconds and multiply by six to get the per-minute rate.
(Based on Information Provided by the President's Council on Physical Fitness and Sports)