Gym Science - Ask the guys in the gym how many sets and reps to do and you'll get almost any answer. You'll hear about people who "got big" doing this and didn't get big doing that, or their own personal experience. Or that "it doesn't really matter because everyone is different," and you need to do "change it up" periodically. They may have stories of a body builder they know, but most of us aren't body builders and don't spend the time, follow the diet or take the supplements and risks that a body builder might to achieve results.
Exercise Science - As an alternative, you could turn to a large body of scholarly research on exercise programs published in peer reviewed journals in which all kinds of people - from young athletes to normal healthy adults to the elderly - were tested and results were compared. The studies considered the different goals, summarized to the right, and are fairly consistent in their findings and lead to the following recommendations. The following recommendations for sets and repetitions are from the National Academy of Sports Medicine:
|1-3 sets of 12-20 repetitions @ 60-70% of 1RM* w/0-:90 rest
|3-6 sets of 1-12 repetitions @70-100% of 1RM w/:45-5:00 rest
|3-5 sets of 8-12 repetitions @70-85% of 1RM w/0-:60 rest
|3-6 sets of 1-10 repetitions @30-45% of 1RM &/or up to 10% of body weight w/3:00-5:00 rest
*1RM=1 Repetition Maximum
We all have a different mix of the 3 muscle fiber types, different diets, and our bodies respond differently to training, however, these have been proven to produce the desired results among thousands of people studied in research. Within 4-6 weeks, your neuromuscular system adapts to a particular workout or training regimen, and you experience a diminishing return on your efforts.
For best results, most people should Periodize their training and cycle between 2-3 different phases of training - or different progressions of weights/sets/repetitions within the same phase - on a 4-6 week basis. An added benefit to Periodization is reduced risk of injury; doing the same workout on a long-term basis is similar to working on an assembly line and increases the risk of repetitive motion injuries. For an article about periodization, scroll down through my weblog.
For those of you who would like to read a very detailed and scientific review of this subject, click here to download a copy of the American College of Sports Medicine's Position Stand: Progression Models in Resistance Training for Healthy Adults.