To maximize muscle development, it is recommended to control the negative (eccentric) phase of your movements. While this phase offers a slight advantage for the upper body, it generates similar gains to those of the positive (concentric) phase for the lower body and overall. The idea that it is radically more effective is therefore a myth.

noli's read

Jeff Nippard’s advice aligns remarkably well with current research data. He relies faithfully on a meta-analysis by da Silva et al. (2025), which aggregates 26 randomized controlled trials. This extensive study confirms that there is no major difference in overall muscle development between positive and negative training. Nevertheless, it validates a slight statistical advantage in favor of the negative phase specifically for the upper body. The historical exaggeration lies in the belief that the eccentric phase is the only true driver of muscle growth. Finally, while it is proven that controlling the descent is beneficial, excessively slowing down this phase (beyond 2 to 4 seconds) has no evidence of additional effectiveness.

the sources

No named source held this one up — that absence is part of the verdict.