Explain 'reversibility' within the SPORT principles

Reversibility within the principles of training suggests skill, strength, endurance and technique can be lost as easily as it can be gain. To improve any part of performance an athlete must train specific skills in order to adapt. But if an athlete does not maintain this level of training the adaptions made to performance can be lost.
Reversibility is very common when athlete's are injured. They are unable to train, therefore, decreases in strength, endurance and technique occur. These reductions can be reversed as well with training.
Reversibility highlights the importance of training to maintain performance.