At one time, heart rate is widely accepted as a good method for measuring the intensity while running, swimming, cycling and other aerobic activities. However, there are many new researches that suggest Heart Rate should not be the "end all" training that it once was. Since so many conditions can effect your heart rate to rely on a set number to gauge your work would be an error.
During the exercise the heart is working and by understanding our bodies reaction to the effort we can work hard or easier to ensure a proper training effect.
The heart rate you should maintain is called your Target Heart Rate. There are several ways of arriving at this figure. The best method to find your maximum heart rate is to go to a medical or sports clinic and have a stress test. One of the simplest is: Maximum Heart Rate (220 - age) X 70%. Thus, the target heart rate for a 40 year-old would be 126.
Some methods for figuring the target rate take individual differences into consideration. Here is one of them.
1. Subtract age from 220 to find Maximum Heart Rate.
2. Subtract resting heart rate (see below) from maximum heart rate to determine Heart Rate Reserve.
3. Take 70% of heart rate reserve to determine Heart Rate Raise.
4. Add heart rate raise to resting heart rate to find Target Rate.
Resting heart rate should be determined by taking your pulse after sitting quietly for five minutes. When checking 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 pulse for 10 seconds and multiply by six to get the per-minute rate.
Which ever method you utilize understand it is only a starting point and not an exact number. By keeping a record of your exercise sessions and noting your heart rate you will state to have a better understand on your body is reacting to training. This information will help you determine the progression of your exercise plan and let you know if you are over training.