Your body is finely tuned to listen for its individual tolerance and pain is a red flag that you have pushed the physical boundaries too far. Pain signals that something is wrong and ignoring the signal can result in injury. Fatigue, on the other hand, can be an indicator that the body is being pushed within a training range. A common measurement of gauging whether a training session is too intense is to use the RATE OF PERCEIVED EXERTION SCALE (Borg's Scale of 6 - 20). Rate of Perceived Exertion asks you to evaluate the entire body's response to the exercise session - fatigue, sweating, muscular tension, breathlessness. Look within and ask yourself to sense all the levels of exertion of physical stress, effort and fatigue.

Look at the rating scale below while you are engaging in an activity; it ranges from 6 to 20, where 6 means "no exertion at all"and 20 means "maximum exertion." Choose the number from below that best describes your level of exertion. This will give you a good idea of the intensity level of your activity, and you can use this information to speed up or slow down your your movements to raech your desired range. Note - If you multiply the RPE number by 10 it is equivalent to heart rate per minute (a resting heart rate) or RPE 13 (somewhat hard) x 10 = 130 bpm.

Try to appraise your feeling of exertion as honestly as possible, without thinking about what the actual physical load is. Your own feeling of effort and exertion is important, not how it compares to other people's. Look at the scales and the expressions and then give a number.

 6   No exertion at all
 7   Extremely light (7.5)
 8
 9   Very light
10
11  Light
12
13   Somewhat hard
14
15   Hard (Heavy)
16
17   Very hard
18
19   Extremely hard
20   Maximal exertion

9 corresponds to "very light" exercise. For a healthy person, it is like walking slowly at his or own pace for some minutes.

13 on the scale is "somewhat hard" exercise, but it still feels OK to continue.

17 "very hard" is very strenuous. A healthy person can still go on, but he or she really has to push him - or herself. It feels very heavy, and the person is very tired.

19 on the scale is an extremely strenuous exercise level. For most people this is the most strenuous exercise they have ever experienced.

Borg RPE Scale
(c) Gunnar Borg, 1970, 1985, 1994, 1998

Sarah Collins, Exercise Physiologist, St. Vincent's Medical Center