The target heart rate for a 20-year-old is between 100 and 170 beats per minute, whereas the target heart rate for a 40-year-old is between 90 and 153 beats. A 55-year-old person has a target heart rate zone of 83 to 140 beats per minute, according to the American Heart Association.
Someone who is 30 years old should strive to keep his heart rate between 95 and 162 beats per minute during physical activity, with a maximum heart rate of about 190 beats. For those between the ages of 45 and 50, the target heart rate zone is about 85 to 149 beats per minute, claims the American Heart Association.
To determine the exact target heart rate, subtract the individual's age from 220. The target heart rate zone is between 50 and 85 percent of the maximum heart rate. To verify the current heart rate, use the tips of two fingers, and place them on the inside of the wrist. Count the number of pulses for 10 seconds. Multiply that number by six in order to determine the number of heartbeats per minute, reports the American Heart Association. Consistently monitoring the heart rate during exercise allows an individual to increase or decrease the amount and difficulty of the activity.