Two of the most important aspects of an effective strength training routine include volume and intensity. Volume refers to the number of sets and reps performed for a given resistance exercise, while intensity refers to the amount of resistance used.
To determine the amount of sets and reps you should perform and how much weight you should use, first you’ll want to establish a clear cut goal. What do you hope to accomplish through strength training? The ideal amount of reps and sets performed for someone aiming to build muscle mass will be different than for someone who wants to increase muscular endurance.
Once your goal is established, you may want to determine your one rep max (1RM), or the greatest amount of weight that your muscles can bear while successfully completing one repetition of an exercise. This is one benchmark that you can use to later determine the amount of weight you’ll need to use in order to reach your goal.
However, using your 1RM as a benchmark can be quite time consuming because to maintain accuracy throughout your training program it will need to constantly be recalculated. An alternative and less time consuming method of measuring your base strength includes calculating your repetition max (RM)—the greatest load you can lift for a specific number of repetitions of a given exercise.
Once you have an idea of your base strength you can start to establish a plan for how many reps and sets you will perform as well as the amount of rest that you will take between each set. Depending on your goals you may perform anywhere from 3 to 6 sets with 6-15 repetitions and 30 seconds to as much as 5 minutes of rest between sets.
When it comes to the number of sets performed The American College of Sports Medicine says that multiple set programs are most beneficial for building strength, power, muscle mass and endurance. For those with long term progression goals (as opposed to short term maintenance) periodized multiple-set programs will yield the best results. How to periodize the number of sets you perform will be explained in greater detail below.
If you are training for muscular strength…
The American College of Sports Medicine recommends performing less repetitions (8-12) with maximal or near- maximal resistance (about 75-95% of your 1RM) and with rest periods of about 3 to 5 minutes between sets for multijoint, large muscle group exercises like squats or deadlifts. Slightly shorter rest periods may be sufficient for single-joint movements and exercises that target smaller muscle groups. Perform at least 3 sets of each exercise.
If you are training for muscular endurance…
ACSM recommends performing a higher number of repetitions (about 10-15) with a lesser load (about 40-60% of your 1RM) and with short rest periods of about 90 seconds or less. Perform 3 to 5 sets of each exercise.
If you are training for increased muscle mass…
ACSM recommends performing a high number of reps but with a slightly lesser load (6-12 RM zone) and with rest periods of about 1 to 2 minutes between sets. Perform 3 to 5 sets of each exercise.
The following chart explains the four phases of a traditional four-week linear periodization program:
Just like with any exercise program, you’ll want to make sure to include periodization so that your workouts don’t become too routine. Once your body adapts to the stimulus of the program, it’s important to make tweaks so that you will continue to see improvements. This also includes incorporating a variety of different exercises in your routine.
To read more about progressing your program see: Strength Training 101
Soucre: ACSM's Resources for the Personal Trainer; Third Edition