Perceived Exertion (PE) – HOW HARD ARE YOU WORKING?
Perceived exertion (PE) is a subjective rating of intensity: You judge how hard you’re working. Use a 10-20 scale, with 10 being a brisk walk and 20 an all-out sprint. Fitness gains roll in between 13-15 for endurance; 16-18 for backpacker-beneficial intervals. Heart rate correlates to PE x 10.