Rating of perceived exertion (RPE) is a widely used and reliable indicator to monitor and guide exercise intensity.
The scale allows individuals to subjectively rate their level of exertion during exercise or exercise testing (American College of Sports Medicine, 2010). Heart Online Borg Scale
Two RPE scales are commonly used:
1. the original Borg scale or category scale (6 to 20 scale), and
2. the revised category-ratio scale (0 to 10 scale).