Strength and Neuromuscular Adaptation Following One, Four and Eight Sets of High Intensity Resistance Exercise in Trained Males – Research Review

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 Mar 31. 

The optimal volume of resistance exercise to prescribe for trained individuals is unclear. The purpose of this study was to randomly assign resistance trained individuals to 6-weeks of squat exercise, prescribed at 80% of a 1 repetition-maximum (1-RM), using either one, four, or eight sets of repetitions to failure performed twice per week. Participants then performed the same peaking program for 4-weeks. Squat 1-RM, quadriceps muscle activation, and contractile rate of force development (RFD) were measured before, during, and after the training program. 32 resistance-trained male participants completed the 10-week program. Squat 1-RM was significantly increased for all groups after 6 and 10-weeks of training (P < 0.05). The 8-set group was significantly stronger than the 1-set group after 3-weeks of training (7.9% difference, P < 0.05), and remained stronger after 6 and 10-weeks of training (P < 0.05). Peak muscle activation did not change during the study. Early (30, 50 ms) and peak RFD was significantly decreased for all groups after 6 and 10-weeks of training (P < 0.05). Peak isometric force output did not change for any group. The results of this study support resistance exercise prescription in excess of 4-sets (i.e. 8-sets) for faster and greater strength gains as compared to 1-set training. Common neuromuscular changes are attributed to high intensity squats (80% 1-RM) combined with a repetition to failure prescription. This prescription may not be useful for sports application owing to decreased early and peak RFD. Individual responsiveness to 1-set of training should be evaluated in the first 3-weeks of training.

Background

There has been a literally decades old argument going on regarding the optimal volume of strength training (and here I’m primarily focusing on the argument about doing a single set vs. multiple sets) for various goals including strength, hypertrophy and the training of athletes. 

Claims that “One set is just as good as three” or what have you are often made based on a variety of arguments.  Most of those I’m not going to address here since I want to focus primarily on the research into the topic.  I’m also going to be focusing only on the issue of strength since muscular size gains are sort of a different issue.

In general the proponents of single set training are also advocates of training to failure, that is taking each set to the point of momentary muscular failure (where no more repetitions can be performed). I’d mention only in passing that there can actually be different definitions of failure here.  In contrast, those advocating multiple sets often (but not always) work at something less than the point of failure.  Again, not universal but common as it can be difficult to perform lots of sets to the point of actual failure.

I’d also note empirically that almost all successful athletes, strength/power or other have used multiple sets in training which at least lends some empirical weight to the idea that multiple sets are better.  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 although a good and strong team may beat either (or may lose because something tactically or strategically happened on the field).  Football players also have the additional factor of being so beaten up (especially in season) that they can’t do more than a single set of machine training; they are just too wrecked to do more.  In any case, using football success or failure to ‘prove’ the relative merits of one style of training versus another just sort of misses the point in a lot of ways: the strength training program is at most one part of a very complex sport and win/loss ratios don’t prove anything.

So what does the research on the topic say?  Part of the confusion is that it is actually fairly mixed which makes it possible to draw different conclusions depending on how you look at the issue.  Certainly some data does seem to show that a single set is ‘as effective’ as three although there is also research showing multiple sets to be superior.   A lot of this has to do with the difficulty in designing decent training programs, often far more than just the variable of number of sets is changing and this makes interpretation difficult.   

For example, several of the studies ostensibly comparing different numbers of sets were also looking at periodized training models (so not only did one group do multiple sets, they also use a variety of rep ranges) and as often as not it’s 1 repetition maximum (1 RM) that is being tested.  If the periodization group worked into low repetitions (as they usually do) but the single set group did not, that automatically biases the results towards the multiple set/periodized group.  Simply because a 1 RM requires practice and the group performing lower repetitions gets it.  But you can’t conclude much about the volume of training per se from such a study.

In a related vein, some of the studies, for example, will have the single set group train on machines (as many of the ‘one set to failure’ groups advocate machine training) while the multiple set group will train on compound free weight exercises.  Subjects are then often tested on the free weight movements that only the multiple set group performed; specificity alone would predict superior results but the study design is a bit biased towards the free weight group.

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 (a topic I discuss in detail in the Beginning Weight Training series).   And extrapolating from studies done on beginners to trained athletes clearly misses the point due to changes in what is required to stimulate further gains in trained versus untrained individuals.

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.

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The Paper

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; subjects were excluded if they were listed as taking any performance enhancers.  So these were not total beginners.

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; back squats were not performed during this two week period. A basic three way split (chest/biceps, back/triceps, legs) routine was performed during this period.

The next 6 weeks were the primary training period and subjects were assigned to either a one, four or eight set squat program and the back squat was the only lower body exercise performed.  During this period, a two way split was used with chest/shoulders and arms trained on one day and legs and back trained on the other.  The volume of all exercises except the squat 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.  Basically 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 skinfold.  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 ommission.

Finally, 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).  Ill 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).

I’ve presented the reults below in terms of average changes in squat strength (in kilograms) among groups.

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Time Point 1-Set 4-Set 8-Set
PostWashout 149±7.8 157.3±12.2 162.0±11.8
3 Weeks 155.7±8.8 174.1±12.0 179.5±13.9*,a
6 Weeks 165.5±9.2* 178.2±11.8* 194.0±14.3*,a
Post peaking 166.4±12.0* 179.1±11.8* 199.0±13.7*,a

* indicates a difference from the post-washout period.  the letter ‘a’ indicates a difference from the single set group.

Note that only the eight set group showed further strength gains after the peaking program.   I think it’s interesting that the eight set group made better gains despite starting out with higher absolute numbers.  Usually it’s the opposite with the group that is less well trained that shows the best results.

In terms of body composition, all three gropus showed minor changes, primarily a small loss of body fat but there was no difference beteween 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.

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.

As well, it’s 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.  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. 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).

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My Comments

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). 

That final point has some clear relevance for athletes in a situation where they may have a limited time per year to make strength gains (usually in the early part of the season) before other training becomes too important for them to be constantly wrecking themselves in the weight room.  An athlete with only 8 weeks to improve strength might be best served by a high volume program to get the maximal results in the shortest period of time before reducing weight room work to lower or maintenance levels.  Even short blocks of ‘top up’ training might be best served by higher volumes for the same reason.

Of course this brings up a potential negative of higher volumes: the time and energy commitment.  Athletes often have a lot on their plate in terms of training and spending endless hours in the weight room (if their sport isn’t already based in the weight room like powerlifting or Olympic lifting) may not be a good use of time depending on how their weight room work impacts on other work.  

An athlete for whom strength is a secondary characteristic (see The Sports, Training and Adaptation Continuums) and for whom lots of weight room work impairs their actual sports training wouldn’t be best served by spending tons of time in the weight room regardless of the potential gains.  Clearly for an athlete for whom maximal strength is absolutely required in their sport, putting in the extra volume would appear to be indicated.  Typically those athletes don’t have as many capacities to develop, mind you, giving them more time to invest in the weight room.

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.

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 it.