Training volume, usually counted as the number of hard sets performed, is the variable most often discussed when a home training plan stops working. Three published meta-analyses have pooled trial data on how the number of sets relates to gains in muscle size and strength. This article summarises what each reports, how they count volume differently, and where their limits lie. It covers general evidence about resistance training and is not advice for anyone with an injury or health condition.
Why the counting method matters
The reviews do not use the same unit. Schoenfeld and colleagues (2017) count weekly sets per muscle group. Ralston and colleagues (2017) count weekly sets per exercise, and Krieger (2010) compares single with multiple sets per exercise. A figure such as “10 sets” therefore means different things depending on the paper, and numbers cannot be lifted from one review and applied to another.
Muscle size: the 2017 dose-response meta-regression
Schoenfeld, Ogborn and Krieger pooled 34 treatment groups from 15 studies and related weekly sets to changes in muscle size. Their main results were:
- with weekly sets treated as a continuous variable, volume had a significant effect on muscle size (P = 0.002), and each additional set was associated with a larger effect size of 0.023, which the authors equate to a 0.37% larger percentage gain;
- when studies were split into lower and higher volume conditions, the difference in effect size was 0.241, equivalent to a 3.9% difference in percentage gain (P = 0.03);
- when weekly sets were grouped as fewer than 5, 5 to 9 and 10 or more per muscle, the result was only a trend (P = 0.074).
The authors conclude that the findings indicate a graded dose-response relationship, with greater hypertrophy at higher volumes. The categorical result is worth noting, since it did not reach the usual significance threshold, and these are associations across studies rather than a controlled comparison of one person at different volumes.
Single sets against multiple sets
Krieger’s earlier meta-analysis analysed 8 studies (19 treatment groups) on muscle hypertrophy. Multiple sets per exercise were associated with a larger effect size than a single set, with a difference of 0.10. In a dose-response model, 2 to 3 sets and 4 to 6 sets each showed a trend towards a larger effect than 1 set, but there was no significant difference between 2 to 3 sets and 4 to 6 sets (P = 0.29). The paper’s summary is that multiple sets were associated with 40% greater hypertrophy-related effect sizes than one set, in both trained and untrained subjects. Taken together, the 2010 and 2017 hypertrophy analyses both associate more sets with more growth, and neither identifies a clear point beyond which extra sets stop helping.
Strength: the 2017 weekly-set meta-analysis
Ralston, Kilgore, Wyatt and Baker examined strength rather than size. They pooled 61 treatment groups from nine studies and classed weekly sets per exercise as low (5 or fewer), medium (5 to 9) or high (10 or more). Their findings were:
- strength gains were greater with high weekly sets than with low, with a mean effect size difference of 0.18 (95% confidence interval 0.06 to 0.30), the mean effect sizes being 0.82 for low and 1.01 for high;
- medium sets produced marginally greater gains than low (difference 0.15, confidence interval 0.01 to 0.30, P = 0.04), with heterogeneity between the seven studies in that comparison of 74%;
- the authors describe a graded dose-response relationship between weekly sets and strength gain, and suggest that for novice and intermediate male trainees low set numbers did not lead to the strength gains seen with medium or high volumes.
The paper lists its own limitations. The number of suitable studies was small, only one of the nine used a randomised control design, and the analysis was restricted to male populations. The authors also note that some of the strength increases may reflect repeated one-repetition-maximum testing, a learning effect, rather than the extra sets themselves.
What the evidence supports, and what it does not
- Supported: on average, trials with more weekly sets show larger gains in both muscle size and strength than trials with very few sets.
- Uncertain: how the response differs between individuals, how volume interacts with load, frequency or recovery, and whether results in the studies’ participants transfer to any given home trainee.
- Not established by these papers: an exact optimum. The reviews describe a graded relationship on average.
- Sex: the strength meta-analysis included men only, so it cannot be applied directly to women.
Where equipment enters
These reviews say nothing about products. Equipment matters only in that it determines whether a planned number of sets can actually be performed, for example through enough load range on adjustable dumbbells or a bench and rack that allow the exercises to be trained safely. A related guide on this site covers progressive overload when weights cannot simply be added.
Frequently asked questions
Is one set enough?
Krieger’s meta-analysis found multiple sets were associated with a larger hypertrophy effect than one set, and Ralston’s found low weekly sets produced the smallest strength gains. Neither is a statement about any individual.
Do more sets always give more muscle?
The 2017 meta-regression describes a graded relationship on average. The reviews do not identify a ceiling, and the categorical comparison in that paper was not significant.
Why do the reviews give different set numbers?
They count differently: the 2017 size review counts sets per muscle group per week, while the strength review counts sets per exercise per week.
The bottom line
Meta-analyses of resistance training trials consistently associate more weekly sets with larger gains in muscle size and strength than one set or very few, with the clearest contrasts between very low volumes and higher ones. They count volume differently, contain small numbers of studies and cannot fix an ideal figure, so a plan should be treated as a starting point to adjust and not a formula to copy.
Sources
- Schoenfeld BJ, Ogborn D, Krieger JW, “Dose-response relationship between weekly resistance training volume and increases in muscle mass: A systematic review and meta-analysis”, Journal of Sports Sciences, 2017
- Krieger JW, “Single vs. multiple sets of resistance exercise for muscle hypertrophy: a meta-analysis”, Journal of Strength and Conditioning Research, 2010
- Ralston GW, Kilgore L, Wyatt FB, Baker JS, “The Effect of Weekly Set Volume on Strength Gain: A Meta-Analysis”, Sports Medicine, 2017