The absence of measurable muscle hypertrophy during an initial resistance training phase does not predict the absence of muscle hypertrophy in subsequent training phases, and when major muscle groups are assessed across multiple resistance training interventions, every individual demonstrates some degree of muscle gain.

Study: Higher resistance training volume offsets muscle hypertrophy non-responsiveness in older individuals.

Some people don’t grow muscles with light workouts, but this study shows that if you make the workout harder or longer, they often do grow muscle after all — so not gaining muscle once doesn’t mean you never will.

Study: Repeated Resistance Training Reveals the Reproducibility of Muscle Strength and Size Responses Within Individuals

The study shows that even if someone doesn’t gain muscle in one training period, they usually do in another, and no one failed to gain muscle in all major muscles over time.