We don't know if doing more or fewer sets of weights is better for building upper body muscle in people who already work out — there just aren't enough good studies that look at this specifically.

What we've found so far is that there isn’t enough evidence to say whether high or low resistance training set volumes are more effective for upper body muscle growth in trained individuals [1]. Our analysis of the available research shows that no high-quality studies have directly compared the two approaches in this specific group. We looked at 20.0 assertions related to this question, and all of them point to the same conclusion: the evidence is currently lacking [1]. While we know resistance training helps build muscle, we can’t determine from what we’ve reviewed whether doing more sets (high volume) or fewer sets (low volume) leads to better results in people who already train regularly. Most studies on set volume either focus on untrained individuals or don’t separate upper body muscle growth from overall muscle growth. Our current analysis shows that this gap exists despite growing interest in optimizing training volume. Without direct comparisons, we can’t tell if one approach has an edge. The evidence we’ve reviewed leans neither toward high nor low volume — it simply doesn’t provide a clear picture yet. This doesn’t mean the answer isn’t important. For people trying to build upper body muscle efficiently, knowing the ideal number of sets could make a real difference. But based on what we’ve reviewed so far, we can’t recommend one strategy over the other with any confidence. Practical takeaway: If you're a trained individual focused on upper body growth, there's no clear evidence that more sets are better — or that fewer sets are worse. You may need to experiment with your own routine, adjusting volume and tracking progress over time while staying aware that science hasn’t settled this question yet.