If you have strength trained before you will be familiar with sets and reps. This is basically how many times you perform an exercise in secession (reps, repetitions) and how many times that is repeated (sets). The most common scheme used is 3×10 which is three sets of ten repetitions. The set and rep scheme is what should dictate resistance selection, many people do this backwards. They select a weight, usually too heavy, and perform it as many times as they can. While this will bring about change one typically plateaus quickly and does not achieve their specific goal. This is due to the fact that sets and reps have an inverse relationship which will favor one body system over another. Lower reps stress the neurological system while high reps stress the muscular system. The lower the reps the higher the sets while the higher the reps the lower the sets. Rest between sets will be dictated by reps, the lower the reps the longer the rest. You want to perform in all the ranges but your amount of each will coincide with your goal. To illustrate this lets look at the general set and rep combinations and their typical out comes.
1-3 reps for 5-10 sets will produce more strength
4-8 reps for 3-6 sets will produce a balance of mass and strength
8-12 reps for 3-4 sets will produce more mass gains
12 and up for 1-3 sets will produce more endurance
Using this methodology will allow you to have a better idea of what results your workout will produce. Your set and rep range will also dictate your resistance. If you perform 10×1 you will be going heavy around 90-95% percent of the maximum resistance you can handle in that exercise. Using a range such as 4x 6-8 the resistance will allow you to perform no more than 8 reps and no less that 6, if so you change the resistance to accommodate. The method is more individualized than using pure percentages of maximum lifts because each people has a different composition of muscle fiber types and might be stronger with one scheme than another. It also allows for flexibility if energy levels or recovery is insufficient. Next perioization will discuss which will explain how these schemes work together.