Explain decathlon if you don't know please don't answer

An athletic event taking place over two days, in which each competitor takes part in the same prescribed ten events (100-meter dash, long jump, shot put, high jump, 400-meter dash, 110-meter hurdles, discus, pole vault, javelin, and 1,500-meter run).

The person who utilize the progression principle will keep adding the difficulty of the exercise that he's doing, while the person who does not, will only stay stagnant.  the person that utilize progression principle, will get a stronger endurance because now his body is conditioned to do harsher routines.{the answer was already on verified)