Whether you should lift lighter weights while completing a higher number of repetitions or use heavier weights and completing fewer repetitions depends on your fitness goals. The type of stress that you place on your muscles during your training will directly influence your results. There is no particular right or wrong way to weight train, but your workouts should reflect your training objectives.

Goals of Weight Training

Lifting programs are different whether you’re interested in building strength or increasing muscle mass. Training designed to build muscular strength focuses on the amount of weight that you’re lifting, as your muscles must produce an adequate amount of force to overcome the resistance. Building muscle mass, which is called hypertrophy, focuses on the overall amount of volume of your weight lifting workout.

Lifting for Strength

Increases in strength require you to lift relatively heavier weights. You must complete two to six sets of six repetitions or fewer for each exercise to build strength. The weight that should be lifted during each exercise is 85 percent or greater of your one repetition maximum, or 1RM. Your 1RM is the maximum amount of weight you can complete an exercise for one repetition. Rest periods of two to five minutes between sets are needed when completing intense sets for strength.

Lifting for Muscle Mass

Building muscle mass requires high volume weight training workouts, meaning you will complete a relatively higher number of sets and repetitions of each exercise. Each set in a muscle building program should consist of eight to 12 repetitions each. The amount of resistance you will use to complete a greater number of repetitions is going to be significantly lighter than the weight you’re using when focusing on building strength. Use a resistance load that is 67 to 85 percent of your 1RM when lifting to build muscle mass. Rest periods are shorter during hypertrophy workouts and should only be 30 to 90 seconds.

Considerations

It's important to note that the amount of weight you should use for your weight training workouts should be appropriate to your training volume. You should become fatigued within the assigned number of repetitions. For example, if you’re lifting to build strength and complete more than six repetitions with ease with the weight you’re using, you need to increase the resistance on subsequent workouts. Alternatively, if you’re lifting for muscle mass and are unable to reach eight repetitions when the weight you’re using, lighten the resistance next time. Constantly make adjustments based on the exercise you’re completing and your improvements in abilities.