Muscle hypertrophy does not differ significantly across a wide range of resistance training loads when sets are performed to or near volitional failure.

Study: Muscle hypertrophy and strength gains after resistance training with different volume matched loads: a systematic review and meta-analysis.

When people lift weights until they're too tired to do another rep, whether they use light or heavy weights, they end up growing about the same amount of muscle — as long as they do the same total amount of work.

Study: Divergent Strength Gains but Similar Hypertrophy After Low-Load and High-Load Resistance Exercise Training in Trained Individuals: Many Roads Lead to Rome.

When people lift weights until they can't do another rep, whether they use light or heavy weights, their muscles grow about the same amount — this study proved it by comparing both methods in trained people.

Study: Resistance training load does not determine resistance training-induced hypertrophy across upper and lower limbs in healthy young males.

When people lift weights until they’re too tired to do another rep, it doesn’t matter much if they use heavy or light weights—muscles grow about the same. The study proved this by comparing both types of lifting in the same people.

Study: Influence of resistance training load on measures of skeletal muscle hypertrophy and improvements in maximal strength and neuromuscular task performance: A systematic review and meta-analysis

When people lift weights until they’re too tired to do another rep, whether they use light or heavy weights, they end up growing their muscles about the same amount — the key is pushing until exhaustion.