There are many reasons that can be thrown into the bucket that influence muscle growth. Especially if you have all day to break it down to the molecular level. But since this is going to be a quick read today 1 of 3 simple topics will be discussed and you can test this out today.
“When muscles are mechanically overloaded and then provided with appropriate nutrients and recovery, the body initiates an adaptive response that results in the accretion of muscle proteins.”
— Science and Development of Muscle Hypertrophy by Brad Schoenfeld
Thank you to Brad Schoenfeld first and foremost. Second, his quotes simply says the heavier the weight lifted and the higher the quality of rest/food consumption the more muscle you can build. "Mechanical Tension" is phrase Brad Schoenfeld gives in his book for one of the three important muscle growth factors. Lift heavier and you shall grow.
Let's take a step back. STRATEGICALLY and EFFICIENTLY lift heavier. Try out his words of wisdom and be safe.