For a lot of people knowing how hard a workout should be conducted is that “how long is the piece of string” question.
If is was left to ourselves we could convince ourselves that it is hard enough but in reality most people train either way too hard for their level of fitness or way too low to actually gain any fitness benefits.
So how do you know which is right?
If you are not training via Heart Rate we use a relative scale called Rate of Perceived Exertion (RPE) or the breath scale:
You can see by the shading that it roughly coincides with the 1-5 scale used for Heart Rate Training (as per featured image) and shown below with the relevant Training Effect:
Would you like to know a neat trick?
If you take the scale used in the first image (1-10) and multiply it by 20, it will roughly coincide with your Heart Rate at that level of effort. You can check by counting your pulse for 10 seconds and x6 it.