Three ways you can apply the overload principle are?

The overload prinicple states that for a muscle to adapt and become stronger/bigger, it must be stressed to a level above and beyond it's normal level of stress. This is still somewhat vague, because this principle can be applied to muscular power, strength, and endurance in different ways. In order to reach "Overload", you must stress a muscle to the point of failure (not injury, just to the point where you cannot complete the repetition). If training for endurance, you would use a much lighter weight/resistance (somewhere in the 50-60% 1RM area), at a much higher level of repetitions. Your rest period would also be somewhat shorter, 30sec-1min. Training for strength, you would steadily pyramid your weight up, and your reps down, from 65-85%1RM, with anywhere from 2-3min rest between sets. (Pincivero et al., 1997). Power lifting: power is achieved when you do the maximum amount of work in the shortest amount of time. Current research still debates this, but if you were to do 5+ sets of 3-5 reps at 75-95%1RM, with as little rest as possible between reps, and 1-2min rest between sets, the gretest gains in power would be achieved.