The first thing an athlete must consider when creating an exercise programme is their own individual needs. The needs of an individual could alter due to their fitness level, weight, age, gender or previous injuries.
This means matching training to the requirements of an activity. Different sports (and different positions within sport) require athletes to excel in different components of fitness.
This means gradually increasing the amount of overload during training in order to improve fitness but without injury. In other words, if you increase the intensity of your workouts gradually you will make steady improvements.
The FITT principle works closely with progressive overload to ensure that training results in progression
Rest and Recovery
This is very important during an exercise programme and without rest, progressive overload is unlikely to occur.
This occurs when your body trains beyond its ability to recover.
This means gradually losing fitness and occurs to anybody who stops training.