Borg's rating of perceived exertion scale takes into account the exerciser's own perceptions of their fatigue. On the revised version of the Borg scale, the perceived effort is assigned a rating between 1 and 10. On the 10 point Borg scale, participants should experience RPE anywhere from 4 to 8, which corresponds to an estimated heart rate of 60 to 80% of the estimated maximum heart rate.

• 1 (nothing at all)
• 2 (weak)
• 3 (moderate)
• 4 (somewhat strong)
• 5 (Strong)
• 6
• 7 (very strong)
• 8
• 9
• 10 (very, very strong)

Source: American College of Sports Medicine. 1991. Guidelines of Exercise Testing and Prescription (4th ed.).