Aprinciple of exercise that states that the only way to improve fitness is to increase the demands on the body is

A principle of exercise that states that the only way to improve fitness is to increase the demands on the body is called principle of progression.

Principle progression in physical fitness is all about adding or increasing loads of exercises, other principle is the overload which refers to the amount of load.

earlier philosophers whose work influenced the enlightenment included bacon, descartes, locke, and spinoza. the major figures of the enlightenment included beccaria, diderot, hume, kant, montesquieu, rousseau, adam smith, and voltaire. it spread the ideas of the enlightenment across europe and beyond.