Overload
The overload principle states that in order to keep making gains from an exercise program, you must find some way to make it more difficult. This is because bodies adapt to exercise. The problem is that once your body adapts to a given workload, it will not continue to adapt unless the workload is increased somehow. If you do not continue to adapt, then eventually you will plateau and regress. Having stated that it is necessary to make conditioning programs more difficult, one caution should be kept in mind: you must observe specificity when applying the overload principle. Performing a set of twenty might be a way of making the workout more difficult, but if you need to enhance the phosphagen energy system then you are violating specificity.
Progression
The Principle of Progression in endurance training implies that there is an optimal level of overload that should be achieved, as well as an optimal time frame for this overload to occur. The Progression Principle instructs that the overload process should not be increased too slowly, or improvement is unlikely to occur. However, overload that is increased too rapidly can result in injury issues or muscle damage. Thus, exercising above the target zone is counterproductive and can be dangerous and potentially result in injuries.
Specificity
The principle of specificity states that sports training should be relevant and appropriate to the sport for which the individual is training in order to produce the desired effect. Additionally, training should progress from general conditioning to specific training for the particular skills required in that sport or activity.
Essentially, specificity training means that you must perform the skill in order to get better at it. It is the principle behind that old saying, "practice makes perfect."
That's all i know and i hope its helps
