[3][4][5][6] In medicine, this is used to document the patient's exertion during a test for the severity of diseases.
Sports coaches use the scale to assess the intensity of training and competition as well as endurance.
When a measurement is taken, a number is chosen from the following scale by an individual that best describes their perceived level of exertion during physical activity.
In older individuals, the correlation becomes higher than 10% at the high-end of the scale, as maximum heart rate declines with age.
More recent research points to that being physically active in outdoor environments, compared to indoors, to a varying degree can lower (23-66 %) the perceived exertion that at a given physiological exercise intensity is connected to in laboratory or other indoor conditions.