Lifting heavier weights makes you stronger than lifting lighter weights, even if you do more reps.

What we've found so far suggests that training with higher relative loads (>80% 1RM) does not lead to greater maximal strength gains (1RM) compared to training with lower loads, when total volume and proximity to failure are matched. Our analysis of the available research shows no support for the idea that heavier loads are superior under these conditions. We reviewed one key assertion claiming that higher loads produce greater strength gains even when volume and effort are equal [1]. However, the evidence we’ve analyzed does not support this. Instead, 51.0 studies or data points refute the claim, meaning they show similar or better strength gains with lower loads when sets are taken close to failure and total work is matched [1]. This suggests that how hard you push on each set—and how much total work you do—may matter more than how heavy the weight is. We don’t yet have a complete picture, and our understanding could change as more data becomes available. But based on what we’ve reviewed so far, the evidence leans against the idea that heavier weights are required for maximal strength gains if you’re working to a similar level of effort and matching volume. This doesn’t mean heavy lifting isn’t effective—it clearly is. But it does suggest that you can build strength effectively with a range of loads, as long as you’re challenging your muscles and doing enough total work. Practical takeaway: You don’t need to always lift very heavy to get stronger. Lifting lighter weights with good effort and enough total volume can work just as well.