The load used during an exercise is a decisive, yet often overlooked, variable for evaluating the specific involvement of each muscle in a movement.

noli's read

Greg Nuckols highlights here a fundamental principle of biomechanics applied to strength training. Research confirms that muscle recruitment is not fixed: it varies dynamically based on relative load (percentage of maximal strength). For example, studies using electromyography (EMG) show that as a load increases, the central nervous system recruits more motor units, sometimes altering the relative contribution of synergistic muscles (meta-analysis, Vigotsky et al., 2018). What Nuckols points out is quite accurate: relying solely on technique or the 'theoretical' exercise without considering intensity can be misleading. This is not an exaggeration, but a technical nuance often ignored in mainstream fitness discourse. The scientific literature firmly supports that load is a major lever for modulating the mechanical stress imposed on specific muscles. In summary, the point is factually solid and helps better understand why the perception of an exercise changes with the weight on the bar.

the sources

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