Reversibility

In 2000 I wrote, published and claimed copyright on this concept (bolding added now):

This principle simply states that once you remove the stimulus of training, the physical capacities developed as a result of training will diminish, go away. Simply put, if you don’t use it, you lose it.

Understanding this principles will assist you to determine issues such as how many days the athlete can afford to take between sessions of the same type, how many weeks the athlete can take off in the transition phase of the year, and how infrequently the athlete can afford to expose him/her self to specific training to maintain that quality but not lose it.

,,,Another term you may seen used as a synonym is detraining.

I was conducting research and I came upon the following exercise in a publication copyright claimed by another 'author' at a subsequent date (bolding added):

This is the use it or lose it principle. Understanding this principle will allow you to determine the different phases of training, transition times, recovery weeks etc. This is also known as detraining and is a key component behind the success of undulating periodization programs.

And I said to myself: “That looks familiar!” So I cross-referenced it and I said to myself: “Wow! No wonder that looked familiar!”

Published in the absence of credits or references to the origin or permission to use from the original author (myself), and that the 'author' claimed copyright....