It is due to lactic acid which builds up in our muscles
The overload principle is defined as working harder as the body essentially grows fitter. This is to stimulate muscle hypertrophy against resistance as well as overall cardiovascular health. For instance, an experienced body builder should lift more weight up up to failure to grow even fitter.
All cellular activities in living organisms use ATP as a source of energy. This is through cellular respiration, which is absolutely essential to sustaining life.
It's important because it is easy to apply it too tightly and impede circulation. Allows for smoother fit and prevents gaping caused by variation in contour of the limb.
