There has been a literally decades old argument going on regarding the number of sets and strength gains. In examining the issue I want to look at the following paper which addressed the issue.
Marshall PW, McEwen M, Robbins DW. Strength and neuromuscular adaptation following one, four, and eight sets of high intensity resistance exercise in trained males. Eur J Appl Physiol. (2011) Dec: 3007-3016.
Note, this paper only examined strength gains, as will I. The issue of training volume and muscle growth is related but separate.
The Number of Sets and Strength Gains
As I mentioned above, there have been literally decades of arguments between groups recommending a very low or very high number of sets to generate maximal strength gains.
At one extreme are the low-volume advocates who often recommend only a single set of any given exercise (or even for a given muscle group). Invariably these groups (often called High Intensity Training or HIT advocates) recommend taking that set to momentary muscular failure, the point at which no more repetitions can be completed.
In contrast, those advocating multiple sets often (but not always) work at something less than the point of failure. They may use various forms of Rating of Perceived Exertion (RPE), Repetitions in Reserve (RIR) or Repetitions to Failure (RTF) to gauge training in this case. If nothing else, it is generally difficult if not impossible to perform a large volume of training to true failure. It’s simply too exhausting.
The point is often made that, empirically, almost all successful athletes, especially strength/power athletes have used multiple sets. This lends at least real-world evidence to the idea that more sets (up to a point anyhow) are superior to single sets.
One oft brought up exception is football where there are examples of winning teams that use a single set to failure approach winning championships (an equal if not larger number of teams use multiple set programs). The problem being that football is a very complex sport ruled as much by skill, tactics and strategy as what the athlete does in the weight room. A good team will usually beat a strong team and the weight training program itself is very secondary to the activity.
So what does the research on the topic say? Part of the confusion is that the data set is fairly mixed. This can make it possible to draw different conclusions depending on how you look at the issue. Certainly in beginners, there tends to be little difference between 1 and 3 sets per workout but we might ask what relevance this has to trained athletes.
To be honest a lot of this has to do with the difficulty in designing training programs due to the fact that all of the different components of training (volume, frequency and intensity) overlap and interact. You can’t change one variable without considering the others.
For example, many of the studies ostensibly comparing different numbers of sets were also looking at periodized training models. Not only did one group do more sets, they used various repetition ranges, often very low ranges. Since most strength tests are based around 1 repetition maximum, some of the seeming “advantage” would be due to practicing lower repetitions. But this doesn’t let you conclude that the volume per se drove the results.
In other studies, the single set group may train on machines (which is common to that style of training) while the multiple set group performs free weight exercises. When the subjects are tested on the free weight exercises, of course they do better. Specificity alone would predict that but it has nothing to do with the volume of training per se.
Perhaps the biggest issue is the training status of the subjects. As a generality, most of the research showing that one set is as good as three is done in beginners but plenty of other research shows that beginners pretty much make the same gains almost no matter what they do. Extrapolating from studies in untrained individuals to trained individuals is a mistake.
As a final issue, many trained athletes perform far more than three sets of a given exercise (or at least more than three sets for a given muscle group) and it’s possible that studies comparing one to three sets of training simply aren’t looking at volumes that are different enough to see a real difference in gains. A study examining far greater differences in number of sets (while hopefully avoiding some of the issues I mentioned above) might help to determine if more sets are or are not better from the standpoint of strength gains.
Which finally brings me to today’s paper.
Studying Strength Gains and Number of Sets
To address the above issue, the study recruited 43 males who had been performing resistance training at least twice weekly for the past two years (experience was 6.6 +- 1 year) with a minimum back squat of at least 130% of body weight. So a 180 lb lifter would have to squat at least 234. To be honest, this is at best an intermediate strength level. They weren’t rank beginners. But they certainly weren’t well trained. Subjects were excluded if they were listed as taking any performance enhancers.
The training program was divided into 12 total weeks. The first two weeks were a break-in/washout period that simple served to standardize their training and eliminate any residual effects from their previous training. This is important and becoming more so in modern exercise research. Back squats were not performed during this time and the trainees did a basic three-way split routine of chest/biceps, back/triceps and legs.
The next 6 weeks was the primary training period and subjects were assigned to either a one, four or eight set squat program. Importantly, the squat was the only lower body exercise performed. During this time period, a two-way split was used with chest/shoulders/arms trained one day and legs/back trained the other. Except for the squat, the volume of all exercises was identical between groups.
For the squat training, the intensity was set at 80% of 1 their starting 1 RM and all sets were taken to the point of volitional muscular failure. For the multiple set groups, three minutes were taken between sets and all groups performed the same warm-up (10 body weight squats, 10 reps at 50% 1RM, then singles at 60% and 70% of 1RM) prior to the work sets. The only variable between all three groups was the number of sets of squats performed and each group ended up having 11 total subjects.
Following the main training block, all participants performed an identical 4 week “peaking” program consisting of low repetition, high-load exercises combined with ballistic exercises. Squats were performed at 3X4RM for all groups during this period.
The subjects were tested on a variety of things including squat 1RM (which was tested in a fairly standard way with depth taken to a measured knee angle of 90 degrees). As well, to examine neuromuscular factors in strength, knee extension rate of force development (RFD, effectively how quickly a muscle can generate force) along with maximal isometric quadriceps strength, a variety of EMG measured was also made. Finally, body fat and body composition was measured via skinfolds.
All tests were performed after the washout period, at 3 and 6 weeks and again after the 4 week peaking block. One thing that is not described is how weights were or were not progressed throughout the study which is an odd omission.
To examine individual response, the researchers grouped the results for each squat group into high responders (defined as making >20% strength gains), medium responders (10-19% gains) and low responders (less than 10% gains). This was done so they could determine individual variability in the response to the different training volumes.
I’ll come back to this but each squat volume group had it’s share of high responders (3 in the 1 set group, 5 in the 4 set group and 5 in the 8 set group) as well as low responders (6 in the 1 set group, 5 in the 4 set group and 2 in the 8 set group).
Strength Gain Results
I’ve presented the results below in terms of average changes in squat strength (in kilograms) among groups.
.* indicates a difference from the post-washout period. a indicates a difference from the single set group.
What you can see is that, at the 3 week mark, only the 8 set group had made any strength gains relative to the post-washout period or the 1 set group. At the 6 week period, all three groups had made strength gains from the post-washout period but the 8-set group was superior to the 1-set group.
In terms of body composition, all three groups showed minor changes, primarily a small loss of body fat but there was no difference between groups. The 8 set group also saw a significant increase in total body weight possibly suggesting an increase in muscle mass. In terms of the neuromuscular adaptations measured there were no changes in quadriceps force output or activation although all groups showed a drop in rate of force development.
High, Medium and Low Responders
As I mentioned, one observation was that there were high, medium and low responders in all three groups with average increases in squat strength of 29.4±2.2% for high responders, 14.3±0.9% for medium responders and 2.6±2.0% for low responders. 11 of the 13 total low responders were from the one and four set groups although the design of the study makes it impossible to know if these subjects would have responded differently with more sets.
It’s also impossible to know if the 10 high responders in the four and eight set group would have gotten the same results off of one set. That is, it’s possible that these subjects would have been low and high responders regardless of training volume (and certainly emerging research on muscle growth suggests that this may very well be the case).
It’s also impossible to know if the three high responders in the one set group would have gotten different results on the higher volume training programs. The researchers do state:
Nonetheless, that the numbers are so clearly skewed to associate high volumes with responsiveness lends some weight to the argument that regardless of categorical variables, high training volumes are preferred to develop strength.
Of some interest, the researchers point out that the 8 set group was the only group to achieve significant strength gains (compared to the 1-set group) by the three week mark. They conclude that for short-term strength improvement, clearly a higher volume approach is indicated.
Looking at the neuromuscular adaptations, the researchers suggest that the lack of improvement in force output or activation suggests that trained individuals can already recruit maximal numbers of muscle fibers (something I have pointed out for years). They also note that this type of training did decrease explosiveness (as evidenced by decreased RFD), most likely due to the high-intensity nature of the training along with each set being taken to failure. It’s also possible that testing neuromuscular variables with an isolated leg extension doesn’t show possible neuromuscular adaptations during the squat itself.
A final point made by the researchers is that previous studies of one versus three sets may have been limited in that the training volumes were just too similar, they suggest that subsequent research on training volume use at least four sets for the multi-set group in order to give a more realistic comparison (and potentially show differential results).
I don’t have a tremendous amount to add to the above. The study, which was far more well controlled than most previously on this topic (in that only a single variable, the number of sets of back squats done), showed that, on average the higher volumes generated higher strength gains.
Certainly there was some individual response (and clearly a single set to failure does generate significant strength gains in at least some subjects) but, in the aggregate, more people made better gains with the higher volumes. And this was especially true over the shorter periods of time (i.e. only the 8 set group had made significant strength gains by week 3).
Basically, 1 set generated some strength gains but they were sub-optimal compared to a higher training volume. Honestly, for trained individuals I’m not sure that this is a surprise to anybody. Clearly a single all out set can work to some point. But a higher volume, at least up to a point is going to be better for maximizing strength gains. This research bears that out as does basically all real-world experience.
There are a couple of important applications that I think comes out of this research. One of the interesting observations was that, over short periods of time ,the higher volume program was clearly superior. Many athletes have a relatively limited amount of time to build strength before their other training becomes a priority.
An athlete with only 3-6 weeks to really focus on strength training would clearly benefit from a higher volume of training to maximize their strength gains before reducing that to maintenance levels with a much lower training volume. If during their competitive season they had a few weeks where they could “top up” their strength levels, they might also bump their volume to maximize their return.
Mind you, with a high volume comes a large time investment in the weight room. Yes, this might maximize strength gains but that has to be weighed against other factors important to athletes (or even general trainees). If tripling your training time doesn’t give you triple the results, it may not be a good time investment.
In that vein, an athlete with limited time to develop strength might be best served with lower volumes. Depending on the sport, athletes often have a lot of other training which takes priority. Even if one set gives inferior strength gains, it still gives some strength gains. If such low volume training allows the athlete to get in and out of the weight room quickly, that may be worth considering.
Additionally, athletes for whom strength is a secondary characteristic to begin with or for whom lots of strength training might impair performance wouldn’t be well served from putting a lot of time in the weight room regardless of the potential gains. For many sports, strength is purely secondary (or occasionally irrelevant) to performance. Doing a high volume of training is not only a waste of time but tends to impact negatively on what is important.
The Time Issue Revisited
This also brings me to my final point and that is the reality of the time requirements of the high-volume training. Consider that the eight set group was spending 30 minutes squatting twice per week compared to about 5 minutes for the single set group. And that’s just for that one exercise.
By the time you add in other exercises at higher volumes, you’re see a large increase in overall training time. For any given trainee depending on their goals, etc. it may or may not be worth spending that much extra time training for the difference in gains.
That is, a missed point in a lot of the single versus multiple set arguments tends to ignore the time commitment (along with the goals, etc.) of the trainee. For someone with very limited time and modest training goals (i.e. general trainee looking for basic strength, health, etc.) a low volume of training may give them all the gains that they want or need.
Even if a higher volume would generate greater strength gains, there is always a huge point of diminishing returns in this: you end up spending 4-5 times as long in the gym for far less than 4-5 times the gains. Whether that time investment is worthwhile simply depends on the situation.
High, Low and Medium Responders Revisited
Finally I’d note that the presence of high, medium and low responders in all three groups (again noting more high responders in the higher volume groups and more low responders in the single set groups) does lend at least some weight to the idea of individual response although it’s impossible to know if any of the subjects would have gotten different results on the different programs. But clearly some people get excellent results from low volumes (while others get nothing) and vice versa.
Many coaches and trainers tend to engage in some projection, often assuming that what works for them will de facto work for anyone that they train. It may be that some of the one set to failure proponents are the high responders from that type of training, but that doesn’t mean that everyone will be. And, again, vice versa. Just because one person gets the most results out of lots of volume doesn’t mean that everyone else will.
Addressing this within the context of the current study, the researchers state:
We recommend that responsiveness to single-set training be evaluated in the early stages (<3-weeks) of a training program, with progression to higher volumes of training in those who are not responsive to lower training volumes.
Basically, if low volumes are working for someone, that’s great. If not, change something.