Final answer:
The statement is true; training with approximately 6 to 12 repetitions is effective for inducing muscular hypertrophy, which is optimal for growth in muscle fiber size due to the intensity and volume balance.
Step-by-step explanation:
It is true that training using roughly 6 to 12 repetitions is most effective for achieving muscular hypertrophy. This repetition range strikes a balance between sufficient intensity and volume, leading to significant tension on the muscle fibers, which is necessary for growth. Hypertrophy occurs when there is an increase in the size of muscle fibers, rather than the creation of new ones. When resistance exercises are performed within this rep range, and accompanied by an appropriate load that challenges the muscles, the result is an increase in the size of muscle fibers (hypertrophy) due to the addition of structural proteins.
According to research, for hypertrophy to take place, resistance training exercises need to be performed at a high enough intensity to stimulate muscle growth. The muscle adapts to the load that is placed upon it, resulting in a requirement to continually increase the exercise intensity, by lifting heavier weights, to see continued growth. This process enhances the development of connective tissue and strengthens tendons, contributing to the overall muscle mass and the ability to produce more powerful contractions.