Every program has variables or areas that can be changed up.  By properly using these variables, mix & matching, you will be able to reach your desired outcome without hitting a plateau.  These variables include, sets, reps, tempo and rest.

Reps and sets are probably the most commonly known in a workout setting.  Reps are how many times you perform a single exercise movement.  So if you are doing squats and you bend and straighten your knees/ hips 10 times, then  you have done 10 reps.  Sets will tell you how many times to repeat that number of reps.  When you write down three sets of 10 reps, it will look like 3x10.  

While three sets of ten reps is a total of thirty reps, please do NOT do all thirty at one time.  That's just one set of thirty reps.  I prefer to go through and do one set of each exercise, use 60-90 sec rest period and then go through the set of exercises again. Repeat three times.  However, there are several ways to go about it.  It is also ok to do one set, rest 30 seconds and do another set of the same exercise, for example.  The rest variable is important because it determines how much recovery time our muscles have between sets.  This ultimately determines which energy sources we are driving from as well as stressing different systems of our bodies.  The changes in rest periods will allow for variations on training to muscle fatigue, neuromuscular fatigue and also for proper energy activation so that energy stores are working properly when we need them.

Now the less well known variable is tempo.  This is the speed at which the exercise is performed.  The speed of the exercise also determines if training will be for strength, power or endurance.  Tempo is also great for training the body as a whole.  If you train soft/connective tissues in addition to just the muscles to withstand the riggors and stress of training you can work up to more stressful routines.  You will be much less likely to damage, irritate or injure those tissues during your workout.

Keeping the variables changing and working all systems will keep your body from hitting a plateau and ultimately hitting your goals in a  timely manner.  Always follow all the variables when provided a workout as they are all important in reaching your goals.