By Shane Robert
I recently saw a question asked on a social media site that I thought was interesting. While I can’t remember the exact wording, the paraphrased version was something like, “Why do I see so many programs today only call for 2 sets of a movement when programs 10 or 20 years ago always called for 3?” This is an interesting question that, on the one hand, is quite simple but, on the other, doesn’t have as obvious an answer as it may seem if you actually think deeply about it.
The simple answer is this: you can get quite a sufficient (hypertrophic) stimulus from 2 high-quality, or ‘hard’, sets taken to near-failure.
Three sets is rooted in a history that, for good or bad, became detached from its original context. After World War 2, many soldiers and sailors found themselves injured and in need of rehabilitation. The prevailing paradigm of that era’s rehabilitation protocols was to do extremely high repetitions with extremely light weights. A doctor working with these patients, Dr. Thomas Delorme (with contributions from Dr. Arthur Watkins), drew from his background as a weight trainer to change this paradigm—he used this to cure himself of his own classic early 20th century health issues such as asthma and frailness.
Knowing that no one who had built actual muscle and strength used light weights and high repetitions, Delorme settled on a protocol of heavy(er) weights. Delorme laid out his scientifically validated program as follows:
1x10 w/50% of 10 rep max, 1x10 w/75% of 10 rep max, 1x10 w/100% of 10 rep max
With the passage of time, this somehow morphed into the infamous 3x10 prescription commonly seen in nearly every bodybuilding article since the 1960s.
In other words, the last set of Delorme’s protocol is a true high-intensity set. In modern parlance, this would be 0 Reps in Reserve (RIR). Yes, there are 3 ‘sets’, however, you have essentially two warm-up sets that are quite far from failure, and only 1 hard set. Granted, that set is quite hard - it is taken to absolute failure—and a large portion of the hypertrophic adaptation you will get in a workout comes from the first hard set. It’s difficult to put a specific percentage on it, but the first hard set unquestionably gives you a disproportionately large amount of the stimulus, with additional hard sets continuing to produce hypertrophy, albeit with progressively and significantly smaller marginal returns as the set number grows.
These hard sets matter enormously. A set of 10 reps with 0–2 RIR is very different from a set of 10 with 5 RIR. As a general guideline, we can relate RIR to hypertrophy in the following ways:
- 5+ RIR = relatively small hypertrophic stimulus
- 3-4 RIR = perhaps meaningful but probably submaximal stimulus
- 1-2 RIR = very productive
- 0 RIR = highly productive, but potentially more fatigue than necessary
This illustrates why the first two sets in the Delorme protocol are relatively unproductive for hypertrophy.
With that in mind, two hard sets taken to 0–2 RIR could plausibly provide a greater hypertrophic stimulus than the original Delorme protocol, despite consisting of fewer total sets. It would be disingenuous, of course, to leave it there as it is well known that most lifters were not, in fact, following the classic Delorme protocol and, instead, were doing sets across with the same weight. If these sets were as challenging, 0-2 RIR, then, arguably, there would have been a greater stimulus for muscle growth. If, on the other hand, the sets were farther away from failure, as was often the case, with the exception, perhaps, being the last set due to accumulated fatigue, the overall stimulus very well might have been less than that of the 2 sets.
As a practical rule of thumb, sets performed very far from failure tend to provide less stimulus per set, while sets performed within a few repetitions of failure provide substantially more. Going all the way to failure can provide a strong stimulus, but it also tends to increase fatigue disproportionately. It’s simple to visualize as a practical heuristic of hard sets (0-2 RIR):
- 1 set: very stimulating and efficient, but probably leaves hypertrophy potential on the table
- 2 sets: excellent stimulus-to-fatigue ratio
- 3 sets: still very stimulating, but fatigue is likely starting to mount and force output might be diminished, and the number of high-quality repetitions might be lower
- 4–5+ sets for the same exercise: potentially useful, but you're increasingly paying in fatigue for each additional increment of stimulus
Those aren't universal properties of those exact numbers.
Exercise selection, muscle, training experience, proximity to failure, frequency, recovery, and whether the exercise is compound or isolation work all matter.
Ultimately, the likely reason that 2 sets has become popular is an emphasis on harder sets (fewer RIR) and finding a balance between enough work and undue fatigue. This is particularly true if multiple exercises per muscle group are being done in a workout.
Does this mean 2 sets are the perfect amount, or that more sets are useless? Far from it. As with all things, the context matters and training should rarely be static. It is the phasic nature of training, i.e., higher volumes to lower volumes and higher intensities repeated in cycles, in which we tend to see the biggest long-term benefit. For lifters who are pressed for time, two hard sets per exercise, and roughly 6-8 hard sets in a session, can be enough to produce meaningful hypertrophy. That doesn't mean it's the maximum amount of productive training, or that everyone should stop there; it simply provides a guideline for minimum effective dose.
A quick note to end on: this applies to hypertrophy. Building strength is another matter entirely. But that is a topic for another day.
