Regarding what’s better for muscle growth between heavy, moderate, and light loads:

Thus, as a matter of principle, there is no ideal “hypertrophy zone.” From a practical standpoint, however, a case can be made that moderate loads provide the most efficient means to achieve muscle development given that light load training involves performing many more repetitions compared to the use of heavier loads, which in turn increases the time spent training.
Moreover, the high levels of metabolic acidosis that accompany the use of light loads tends to cause discomfort [81], which in turn can negatively impact adherence.

Alternatively, evidence suggests that heavy load training requires more sets to achieve comparable hypertrophy to moderate loads. Not only is this inefficient from a time standpoint, but the combination of heavy loads with high training volumes heightens joint-related stresses and increases the potential for overtraining.


In short, stick to moderate loads (65-75% 1RM max) for 8-12 reps. Easier on joints/tendons and will still achieve the same results.