How Many Sets for Size vs Strength?

While increased muscle size is associated with increased strength it is not a perfect relationship meaning you can increase muscle strength without increasing muscle size.   Research shows that the ideal number of sets for muscle growth vs muscle strength seem to differ, and the ideal number of sets definitely changes as you progress from a beginner to a more advanced lifter.

To tease apart the differences it is useful to review what happens when a person starts doing resistance training exercise and how things change as they have been doing resistance training on a regular basis for 3 – 6 months or longer.

When a person starts doing resistance training they can make very quick gains because they are going through a period of “motor learning” and “neural adaptations” meaning they are learning how to do the exercises.     This process ends pretty quickly in about 3 – 4 weeks of doing resistance training.  During this time strength improvements are not associated with much muscle growth.  Once this honey-moon period ends people start to add muscle if they continue to challenge their muscles sufficiently and this is known as muscle hypertrophy.    

How hard someone trains is measured by how close to complete muscular failure they reach during each set of exercise.  Muscular failure is defined as continuing to do an exercise until you reach a point of fatigue where you can no longer lift a weight using good form.   The closer to this point that you get the more intense the set and sets done to muscular failure are the most intense.

For beginners one set to failure can be sufficient to stimulate muscle growth and strength increases as long as the person continues to increase the resistance when they hit a certain number of repetitions in a set of a particular exercise – somewhere between 8 -12 reps is a good goal.

However, as time goes on many people begin to plateau if only doing 1 set of exercise for each major muscle group.   At this point introducing multiple sets of each exercise is often key to continuing to gain muscle size and strength.

Number of Sets for Size vs Strength

For more experienced lifters the number of sets and rest time between sets should be determined based on goals and performance during each resistance training workout (this is why it is VERY important to record all your workouts listing exercises done, weight or resistance level used, rest time between sets, etc.).  

A recent study in the Journal of Applied Physiology provided some very valuable information about sets for strength vs size.    The study had 85 people do sets of between 8 – 15 repetitions of single-leg knee extensions with weight chosen so they reached muscular failure during each set.    Each participant did one set per workout with one leg and four sets per workout with the other leg.    Muscle size changes were measured with MRI.    60% of the participants failed to gain more than a 3.3% increase in quadriceps muscle size for their leg that only did one set.    For the leg that did four sets per workout only 19% failed to gain significant increases in muscle size.

Other studies have also found that multiple sets are better for muscle size.   However, research on multiple sets for strength gains are not as consistent!   In the study above the four set legs did NOT gain significantly more strength than the 1 set legs.   This does not mean that people focused on strength should not do more than 1 set of exercise.    Most elite powerlifters do multiple sets of exercise.      However, this does indicate that for non-competitive lifters strength goals can probably be met with less sets than those looking to maximize muscle size.

What About Set Intensity and Rest Time Between Sets?

Another key point is that studies clearly show that for increasing muscle size it is very important to come close to muscular failure or actual hit muscular failure during each set.   In addition, shorter rest times tend to be better for muscle growth for more experienced lifters.

This is NOT the case for strength.   Research shows that excellent strength gains can be made doing sets that “leave something in the tank” and not reaching muscular failure while also taking longer rest times between sets.   This does not mean that strength focused lifters should never achieve failure in training.     However, as a person becomes strong it becomes more and more risky to use high loads to complete muscular failure – particularly in major compound lifts like squats and deadlifts.