More Volume, More Gains?
It is becoming increasingly clear in the scientific literature that more volume is the driver of increased muscular hypertrophy over time. Well, up to a certain point! Volume can be increased in a number of ways: intensity (weight), reps and, sets. Increasing those over time leads to an increase in the total volume of work you perform and hence the levels of mechanical tension and metabolic stress induced within muscle tissue. It is these levels of mechanical tension and metabolic stress that are generated that lead to the activation of downstream anabolic (muscle building) responses that lead to eventual muscle gains. It is also becoming clearer that volume is not something you can keep increasing without potential consequences. Eventually, at a given point in your training, you will hit an upper threshold limit (maximum recoverable volume). Exceeding this point will simply start to burn you out and blunt any positive hypertrophic responses. But everyone is different! Some people can tolerate lots of volume, others much less. With experience, you learn to keep volume in check so that training fatigue and recovery are optimally controlled.
A common training method that is frequently employed by those looking to maximise hypertrophy is something called German Volume Training (GVT). GVT consists mainly of performing 10 sets with each set at 10 repetitions (10 x 10!) for two compound exercises at loads of approx. 60% 1RM. The rest times between each set are relatively short (60-90 seconds). Now, GVT is intense, no joke! It consists of a lot of training volume and the rationale for this is pretty simple: more volume, greater levels of mechanical tension and metabolic stress, and thus a larger hypertrophic response. It seems plausible but many people have asked: is GVT really optimal for maximising hypertrophy gains or is it simply too much? Certainly for beginners and early intermediates GVT is going to result quickly in burn out as the threshold for their maximum recoverable volume is going to be pretty low. Which makes sense, the new guys don’t need a lot of volume to make gains. After all, that is the beauty of being a beginner lifter! However, are 10 sets really needed? That is the question everyone currently asks.
There have been quite a few studies performed to investigate the increasing number of sets on increases in muscle size. In a meta-analysis by Krieger (2010), from 8 studies it was found that there was a dose-response relationship between the number of sets that were performed and muscular hypertrophy outcomes. It was observed that 2-3 exercise sets per exercise produced greater gains in muscular hypertrophy than 1 set. But, this trend started to level off at 4-6 sets, with the difference between 2-3 and 4-6 sets being insignificant. However, as Krieger (2010) points out, there were some limitations to this meta-analysis. The lack of studies for one: only 8 were incorporated. That is not a big selection! This limits the statistical power of the analysis. Furthermore, 6 of the studies that were included were those investigating untrained individuals. As we know, untrained individuals respond in a completely different way to trained individuals. Therefore, it was not possible to compare the influence of training experience on set volume. Finally, 6 of the studies compared 1 set with 3 sets and only 2 studies investigated sets greater than 4 on muscle growth. As a result, it was pretty difficult to make definitive conclusion about the impact of 4 or more sets on hypertrophy and especially how this trend relates to the level of training experience you have. While this trend sounds plausible for beginners, I would expect those more experienced to benefit significantly from more than 4-6 sets per exercise.
Krieger (2010). Figure shows the results from 8 studies investigating the number of sets per exercise on muscular hypertrophy. There are significant increases in hypertrophy when 2-3 sets and 4-6 sets are performed over 1 set. However, the difference between 2-3 sets and 1-set was the greatest, with only a small difference being notes between 4-6 and 2-3 sets. This suggested that perhaps a plateau was being reached at around 4-6 sets. But, with the lack of studies investigating more than 4-6 exercise sets on muscular hypertrophy gains, this upper threshold limit could not be identified. Also, the lack of studies conducted in resistance trained individuals make it difficult to extrapolate this dose-response relationship this group.
In a later meta-analysis by Schoenfeld et al. (2016), a dose-response relationship was also found between the weekly number of sets per muscle group and hypertrophy. The weekly number of sets were stratified into >4, (low volume), 5-9 (medium volume) and <10 (high volume). Furthermore, unlike the meta-analysis conducted by Krieger (2010), more studies were now included (15) and on analysis of the data, more weekly sets favoured increases in muscular hypertrophy. But, the lack of data investigating more than 12 sets per week made it difficult to identify whether approx. 10 sets is the threshold or not. At the moment, it is just not clear where this threshold point lies and whether more gains can be made by doing more than 10 sets per week per muscle group. Another limitation is the lack of data regarding resistance-trained individuals with most of the current data being conducted from untrained individuals. Again, because untrained and trained lifters respond differently, these current dose-response relationships cannot be extrapolated to those more advanced.
Schoenfeld et al. (2016). Figure shows the effect sizes for muscular hypertrophy in response to increasing number of sets per week for each muscle group. As you can see, there was a trend towards greater increases in muscular hypertrophy when number of weekly sets (total weekly volume) increased. However, the lack of studies investigating more than 12 sets per week make it difficult to identify an upper threshold (how much volume is too much?). Furthermore, it is difficult to extrapolate this trend to resistance trained individuals since very few studies were conducted on this group.
A 2018 Study
Recently, Hackett et al. (2018) investigated the influence of 5-sets and 10-sets on muscle growth using a modified GVT approach over 12 weeks in resistance-trained individuals. In both training groups, a split-resistance training routine was performed which involved different exercises targeting specific muscle groups during 3 training sessions per week. In both groups, only the number of sets (either 5 or 10) were changed on the first two compound exercises for each session. The remaining exercises were kept at 10 reps at an intensity of approx. 60-80% 1RM with 60-90 seconds recovery time between each set. The same loads were used for each exercise in order to isolate the number of sets as the variable to be investigated. If participants could not perform 10 reps on a given exercise, they were instructed to perform as many as they could so that the load was not changed.
At the end of the 12-week training period, Hackett et al. (2018) found no significant differences in muscle hypertrophy gains between the 5-set and 10-set group. It was hypothesised that the 10-set group would incur significantly more hypertrophy benefits due to this group performing more volume (weight x reps x sets) than the 5-set group and thus accentuating the metabolic stress and mechanical tension implicated in driving muscle growth. However, this was not the case, Hackett et al suggested that perhaps the 10-set group had exceeded the upper volume threshold for muscular hypertrophy, with this being between 5-10 sets. In fact, they suggest that this might lie closer to 5 sets, being in line with those demonstrated by Krieger (2010) of hypertrophy being limited at 4-6 sets. However, there are a few limitations which make it difficult to know for sure if the volume limit is approx. 5-sets for maximal levels of hypertrophy. Again, the sample is small (12 participants). Who knows what the results could have been with a much larger sample. Furthermore, this is one study done with resistance-trained individuals. At the moment, very few studies have been conducted using resistance-trained individuals with most of the results derived from untrained lifters. This makes it difficult to truly identify the optimal levels and upper limits of training volume (in terms of sets) on muscular size in these individuals.
Hackett et al. (2018). Figure shows the changes in muscular hypertrophy following a 12-week training period in resistance-trained individuals who underwent either 5-set or 10-set modified GVT program. Again, there were very little differences in muscle gains between both groups. It was suggested that around 5-sets was a threshold limit and further increases would lead to no further gains in muscle size. However, this needs to be further tested. Moreover, with such a small time scale and sample size, the statistical strength of such results are relatively small and more (and larger) studies need to be conducted in resistance-trained individuals to further clarify the results obtained here.
More Sets, More Muscle Gains?
So far, it seems that there is a dose-response relationship between the number of sets performed and muscular hypertrophy gains. In other words, more volume, more growth. However, while Krieger (2010) investigated number of sets per session (total session volume), Schoenfeld et al. (2016) investigated the weekly number of sets per muscle group (total weekly volume). In both cases, there was a positive trend between more sets and more growth. But, in both studies, no upper limits could be reliably concluded. While Krieger (2010) suggested that individuals should aim for 2-3 sets per exercise for optimal hypertrophy, Schoenfeld et al (2016) put forward the idea that total weekly sets might be a better indicator of training volume, with at least 10 weekly sets per muscle group being performed in order to maximise muscle size. While the study by Hackett et al. (2018) falls somewhat in line with the findings of Krieger (2010) it must be noted that Kriegers results are based mainly on those from untrained individuals, while those of Hackett et al. used trained lifters. Moreover, with the lack of data surrounding resistance-trained individuals and the lack of data surrounding upper volume limit thresholds, it is difficult at present to define exact numbers. Not to mention, every individual responds differently, has different tolerances to training volumes and, capacities for recovery, which further complicates things. One thing is for certain however: more volume over time is the driver of increased hypertrophy over the long-term.