Is there a level on the Borg scale that corresponds to therapeutic activity? How do we know what a specific patient should be at for a given condition?

The Borg Rating of Perceived Exertion (RPE) is a way of measuring the intensity level of physical activity. Perceived exertion is how hard one feels their body is working. It is based on the physical sensations a person experiences during physical activity, including increased heart rate, increased respiration or breathing rate, increased sweating and muscle fatigue. Although this is a subjective measure, a person’s exertion rating may provide a fairly good estimate of the actual heart rate during physical activity. The (RPE) is also the preferred method to assess intensity among individuals who take medications that affect heart rate or pulse.

All activities/exercises designed as part of a cardiac rehabilitation program are therapeutic in nature. The RPE just happens to be a self-monitoring tool that is taught to patients to help them determine the intensities at which they are exercising. Being subjective, the RPE varies from patient to patient and has clinical implications – such as deciding to continue or terminate an ongoing exercise program.

Perceived exertion ratings between 12 to 14 on the original 20 point Borg Scale suggests that physical activity is being performed at a moderate level of intensity. By self-monitoring how hard their bodies are working, patients can adjust the intensity of the activity by speeding up or slowing down their movements. Through experience, it becomes easier to know when to adjust the intensity of exercise. For example, a patient who wants to engage in moderate-intensity activity would aim for a Borg Scale level of ‘somewhat hard’ (12-14). If the exertion is described as ‘very light’ (9 on the 20 point Scale) then, the intensity may be increased. On the other hand, if the exertion felt is described as ‘extremely hard’ (19 on the 20 point scale), then there is a need to slow down movements in order to achieve the moderate-intensity range.

Finally, a high correlation exists between a person’s perceived exertion rating times 10 and the actual heart rate during physical activity; so a person’s exertion rating may provide a fairly good estimate of the actual heart rate during activity. For example, if a person’s rating of perceived exertion (RPE) is 12, then 12 x 10 = 120; so the heart rate should be approximately 120 beats per minute. Note that this calculation is only an approximation of heart rate, and the actual heart rate can vary quite a bit depending on age and physical condition.