Rate of perceived exertion is defined as “how hard you feel your body is working”. It is based on your subjective perception of how hard YOU feel you are working (breathing, fatigue, sweating). The subjective score has been found to correlate with heart rate. The most popular scale is known as The Borg scale which rates exertion from 6-20. 6 is “no exertion at all” and 20 is ”maximal exertion”. This scale has been revised to a 10-point scale which is much easier to work with. Here 0 is nothing and 10 is very, very heavy. Depending on the type of training session you are having, you may choose to work at a low, moderate, high or varying effort levels. With ChiRunning®, it has been found that increasing speed results in a much lower increase in RPE compared to power running techniques; the speed increase is assisted by gravity by increasing the lean and by relaxing (yes, relaxing) the trunk and pelvic muscles, allowing for more pelvic/trunk rotation which opens up the stride. In contrast, with power running, speed increases largely with increased use of the legs and a much higher increase in RPE.