While the majority of individuals exhibit similar hypertrophic responsiveness across high- and low-load resistance training, a subset may demonstrate load-specific responsiveness, though such responses are inconsistent and not reliably predictable.

Study: Higher- and lower-load resistance exercise training induce load-specific local muscle endurance changes in young women: a randomised trial.

Some people’s muscles get stronger in a way that matches the weight they trained with—light weights help more with light tasks, heavy weights help more with heavy tasks—but this doesn’t happen the same way in every part of the body, so you can’t always predict it.

Study: Individual muscle hypertrophy in high-load resistance training with and without blood flow restriction: A near-infrared spectroscopy approach

Some people’s muscles grow better with heavy lifting, others don’t care as much — this study found that even when using heavy weights, some people responded better to one version than another, showing that not everyone reacts the same way.

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

People’s muscles grow differently no matter if they lift heavy or light weights — some grow a lot, some grow little, but it’s not because of the weight; it’s because of their body’s natural differences, and you can’t reliably predict who will respond better to heavy vs. light lifting.

Study: Potential Moderators of the Effects of Blood Flow Restriction Training on Muscle Strength and Hypertrophy: A Meta-analysis Based on a Comparison with High-Load Resistance Training

Some people build muscle the same way no matter if they lift heavy or light weights, but others—especially those who already train a lot—build more muscle with light weights and restricted blood flow, showing that not everyone reacts the same way.