And you know what? This scheme mostly works, especially if you're just starting out with strength training-because everything works in the beginning. The more effective strategy (especially once your beginner's gains are behind you) is to tailor your primary set-and-rep scheme to best suit your specific training goal.
Of the countless ways you can structure your sets, there are three basic schemes that every lifter must know. If your objective is strength or power (think: heavy lifting), the textbook advice is to perform 3 to 5 sets of 2 to 6 reps per exercise. For hypertrophy (building muscle), the sweet spot is 3 to 4 sets of 6 to 12 reps. And if your objective is muscular endurance, shoot for 2 to 3 sets of 12 to 20 reps.
In each case, the key is to use the heaviest resistance that will allow you to complete all of your reps and sets with good form. You also want to allow yourself just enough time to recover between sets to maintain a high level of performance: 2 to 5 minutes for strength and power, 30 to 90 seconds for hypertrophy, and just 30 seconds for endurance.
Your move: Focus on the training scheme that best matches your fitness goals-but don't hesitate to include others in your workout plan as well. Why? Because their benefits overlap.
If your goal is hypertrophy, for example, lifting primarily in the 6 to 12 rep range will help you target your type II muscle fibers, which are the largest and have the greatest growth potential. But if you want to maximize your gains, you can't neglect your more endurance-oriented type I fibers, which respond best to high rep sets. By including a range of reps and sets in your workout plan, you'll make sure that you optimize your training stimulus and fast-track your results.