Rating of Perceived Exertion

There are various scales that he used to gauge exercise intensity. The most famous is Borg's 15 point Rating of Perceived Exertion (RPE). Another RPE scale by Borg is the 10 point Category Ratio scale (CR10), sometime CR10 is called the "modified RPE scale". RPE can be used to calculate the difficulty of the training as TRIMP and is related to The Ivan Scale Of Perceived Suffering.

1 Borg's RPE Scale

This scale was based on earlier work where it was noted that there was a correlation between Heart Rate and perceived exertion. Based on this observation, Borg created a scale that roughly equates to 1/10 the Heart Rate of the healthy middle-aged male. This scale starts at 6, as 60 is roughly the resting Heart Rate of a healthy individual. The top end of the scale is a 20, which again approximates the maximum Heart Rate of 200. (Note that actual resting and maximum heart rates vary a lot and the values of 60 and 200 are broad generalizations.)

Rating	Description	Notes
6	Rest	Reading a book, watching TV
7	Very, very light	Standing, or sitting while playing cards, knitting.
8
9	Very light	Walking slowly
10		Easy warm up
11	Fairly light	Walking steadily, but not enough to noticeably change your Breathing.
12
13	Somewhat hard	Steady state, but okay to keep going. Breathing increased noticeably, but not "out of breath"
14
15	Hard	Swimming or cycling hard enough to make Breathing harder and raise Heart Rate.
16
17	Very hard	A healthy person can keep going, but has to push.
18
19	Very, Very hard	The most strenuous exercise most people experience. Finishing kick on a race or a hard sprint.
20		All out maximum effort

2 Borg CR10 Scale

The Borg CR10 Scale is more useful for statistical analysis than the Borg RPE. On the CR10 scale, twice the rating is likely to be twice as hard. While the Borg CR10 scale does not correspond with any physiological measures such as Heart Rate, this is not really an issue in practice. While this scale has a maximum value of 10, Borg's definition says that it is acceptable to use greater numbers if the subject so desires.

Rating	Description
0	Nothing at all
0.5	Very, very weak
1	Very weak
2	Weak (light)
3	Moderate
4	Somewhat strong
5	Strong (heavy)
6
7	Very strong
8
9
10	Extreme