Question

What training principle states that you must continue to exercise to maintain fitness?

Answer 1

You can't just workout for a week and think that you can stop and your body will stay loke that forever you must continue to exercise & also not stick with the exact same exercise forever because your body does grow accustome to certain things that you keep constant in your life so you should switch it up and make it more of a challenge to make your body stronger and maintain your fitness

Answer 2

I think you forgot to give the options along with the question. I am answering the question based on my research and knowledge. "Reversibility" is the one training principle that states that you must continue to exercise to maintain fitness. I hope that this is the answer that has actually come to your great help.