Drop sets are a so-called advanced muscle-building technique.

Generally, a drop set involves performing repetitions to failure with a given load and then immediately reducing the load (typically by 15-25%) and performing repetitions to failure again. Typically, one to three load reductions are done, but more can be done.

You can also perform multiple drop sets for an exercise, separated by some rest interval duration.  

A potential reason drop sets could build more muscle is that when you perform repetitions to failure with a given load, your muscles are technically not fully fatigued, as they could still perform repetitions with a lighter load. 

By using drop sets and performing further repetitions to failure with lighter loads, you are enhancing the fatigue experienced by the muscle, potentially implying a better muscle-building stimulus.

However, do drop sets have any support in the research?

Firstly, we’ll explore a new study by Varovic et al.

Secondly, we’ll fit this study into the context with the rest of the drop set research and make some conclusions.

New Study on Drop Sets

Subjects

Varovic et al. recruited 16 men with less than 1 year of training experience.

This could technically include individuals with no previous training experience, but the researchers unfortunately provided no further details on whether this was actually the case. 

Nevertheless, each subject randomly had one leg assigned to a drop set or normal condition.

Training Protocol

Both legs were trained on the unilateral leg extension, mainly three times per week for 8 weeks.

With the normal condition leg, each session consisted of performing 2-5 sets of repetitions to failure with a 15 rep-max load.

120 seconds of rest were used between sets.

With the drop set condition leg, each drop set involved first performing repetitions to failure with a 5 rep-max load, immediately reducing the load by 20% and performing repetitions to failure, and then reducing the load one last time by 10-15% and performing even more repetitions to failure.

2-5 drop sets were performed per session, separated by 120 seconds of rest.

Measurements

Vastus lateralis and rectus femoris thickness was each measured at 30%, 50%, and 70% of the muscle’s respective length before and after the study for both legs.

Results

At all measured regions of the vastus lateralis, and at 70% of the rectus femoris’ length, increases in thicknesss were similar between both conditions. 

However, at 30% and 50% of the rectus femoris’ length, increases were greater for the drop set condition.

Therefore, it seems drop set training was better at growing more regions of the quadriceps.

Drop Set Research With Isolation Exercises

It’s potentially notable the leg extension, an isolation exercise, was used in the study by Varovic et al.

Isolation exercises involve movement at one joint, meaning one muscle group is trained.

When looking at the rest of the research using isolation exercises, the results similarly seem promising for drop set training. 

Fink et al. had 16 men with prior training experience, but minimally trained in the last year, perform the triceps pushdown twice per week for 6 weeks.

A normal group, each session, trained the movement with 3 sets of repetitions to failure with a 12 rep-max load, using 90 seconds of rest between sets.

A drop set group, each session, performed repetitions to failure with a 12-rep max load, and then subsequently performed repetitions to failure with a 20% lighter load three consecutive times in a row. They only performed this single drop set in a session.

Increases in triceps cross-sectional area, measured at 50% of the upper arm length, favored the drop-set group.

These results are quite impressive.

As just noted, the drop set group only performed a single drop set in their session.  

The normal group, opposingly, performed 3 sets in a session. 

If the drop set group performed three of their drop sets, they may have experienced potentially even more growth, given more volume (in the form of sets) seems to be closely related to muscle growth (at least up to a certain point).

Another study by Okazi et al. assigned the arms of 9 untrained men into one of three conditions: a high load, light load, or drop set condition.

Subjects trained both arms with a unilateral dumbbell curl, two to three times per week for 8 weeks.

The high load condition, each session, involved performing 3 sets of repetitions to failure with an 80% one-rep max load, using 3 minutes of rest between sets.

The light load condition, each session, involved performing 3 sets of repetitions to failure with a 30% one-rep max load, using 90 seconds of rest between sets.

The drop set condition first involved performing repetitions to failure with an 80% one-rep max load, and then immediately performing subsequent repetitions to failure with 65, 50, 40, and 30% one-rep max loads. They only performed this single drop set each session.

Increases in cross-sectional area of the elbow flexors (which consists of the biceps and brachialis in this case), at 60% of the upper arm length, were similar between all three conditions. 

Like the last study, the drop set conditon only performed a single drop set. Although, 4 load reductions were performed, which is quite a bit. 

Nevertheless, it’s plausible if they performed further drop sets in a session, growth could have been even more compared to the other high and light load conditions.

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Drop Set Research With Compound Exercises

As for compound exercises, which are exercises that train two or more muscle groups thanks to the movement of two or more joints, the evidence is less promising for them with drop sets.

Angleri et al. assigned each leg of a group of 16 men with at least 4 years of training experience into a drop set or normal condition.

Both legs were trained on the unilateral leg press and leg extension for 12 weeks. 

The leg extension is of course an isolation exercise, but the leg press is compound.

The normal condition, each session, involved 3-5 sets of 6-12 repetitions to or very close to failure, using 2 mins of rest between sets.

For the drop set condition, each drop set involved first performing repetitions to failure with a 75% one-rep max load, immediately reducing the load by 20% and performing repetitions to failure, and then reducing the load one last time by 20% and performing even more repetitions to failure.

3-5 drop sets were performed each session, separated by 2-minute rest intervals.

Increases in cross-sectional area of the vastus lateralis, measured at 50% of the thigh length, were similar between both conditions. 

Now, one limitation of this study is that only one region of the vastus lateralis, which is a large muscle, was measured.

Fortunately, this limitation is less so in a study by Enes et al.

18 men with at least 2 years of training experience were assigned into a normal or drop set group.

Both groups trained the back squat, leg press, and leg extension, twice per week for 8 weeks. Again, the leg extension is an isolation exercise, but the back squat and leg press are compound.

The normal group, each session and for each exercise, performed 4 sets of 12 repetitions with a 70% one-rep max load, using 120 seconds of rest between sets.

The drop set group, each session, involved performed 10 reps with a 75% one-rep max load and then immediately reducing the load to 55% one-rep max and performing a further 6 repetitions. 3 of these drop sets were performed for each exercise, separated by 120-second rest-intervals.

Lateral thigh thickness (which includes a combination of the vastus lateralis and vastus intermedius) was measured at 30%, 50%, and 70% of the thigh length.

Increases at all three measured regions were similar between both groups. 

More Intense Drop Sets May Be Unsuitable With Compound Exercises

It’s worth noting that the drop sets used in the study by Enes et al. can be thought of as less intense than typical drop sets.

They performed a prescribed number of repetitions rather than training all out to failure.

They also only performed one load reduction per drop set. 

With more intense drop set protocols, I think there are some potential reasons as to why they may not be the most suitable with compound exercises, particularly with free weight compound exercises like the back squat.

Firstly, as compound exercises require the coordinated movement of two or more joints, they generally require more skill and concentration to smoothly execute versus isolation exercises

Drop sets that involve repetitions to failure and multiple load reductions, due to their highly fatiguing nature, may cause a meaningful breakdown in technique. 

This problem may be more relevant for less experienced individuals.

Secondly, central fatigue could potentially be an issue.

Remember, muscles produce force thanks to the electrical signals they receive from that central nervous system (the brain and spinal cord).

Central fatigue refers to a decrease in these electrical signals. This causes a reduction in the number of muscle fibers recruited and/or the amount of force they generate, something not favorable for optimal muscle growth.

Central fatigue is likely produced in many cases of training.

However, drop sets with compound exercises may produce central fatigue to a magnitude that could be problematic.

I speculate this for two reasons:

Firstly, the longer the muscle contraction duration, the more central fatigue generated. 

Due to multiple load reductions, drop sets prolong the duration of your sets, and thus muscle contraction duration.

Secondly, there’s some evidence to suggest the more muscle mass involved in an exercise, the more central fatigue generated. Compound exercises involve more muscle mass than isolation exercises.

Combine these two reasons and we could hypothesize that drop sets with compound exercises may produce central fatigue that interferes with the stimulus. 

However, it’s essential to recognize this is just a hypothesis. The notion that compound exercises generate more central fatigue is not completely supported by the research itself.

Conclusion

To conclude the article, the research on drop sets with isolation exercises looks promising.

1 study found that with a leg extension, multiple drop sets per session produced greater regional quadriceps growth than multiple normal sets.

A second study found with a triceps pushdown, a single drop set produced more triceps growth than multiple normal sets.

While a third study found with a dumbbell curl, a single drop set produced similar elbow flexor growth to multiple normal sets.

Now, in these two studies that only used single drop sets, it’s potentially plausible that if they performed more drop sets per session, the results may have been even more favorable for drop sets.

With studies that have included compound exercises, drop sets appear less promising.

Two studies in which multiple drop sets were performed with either the leg press and back squat found no advantage with them.

As a final note, it’s worth mentioning that in total, there are only 5 studies assessing drop sets and muscle growth, which is far from a substantial number.

The conclusions in this article are derived from my interpretations of this limited number of studies.

Future research could definitely come along and change the conclusions made in this article.

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