What is RPE and when do you use it?

Rating of Perceived Exertion

Explanation:

When used in a personal setting it can be a way to determine your training intensity, as opposed to using percentages. On a coaching level RPE can be a way to gain an understanding of an athlete's level of exhaustion, plus what they have left in the tank

fluid balance is an aspect of the homeostasis of organisms in which the amount of water in the organism needs to be controlled, via osmoregulation and behavior, such that the concentrations of electrolytes (salts in solution) in the various body fluids are kept within healthy ranges. the core principle of fluid balance is that the amount of water lost from the body must equal the amount of water taken in.