What is the theory of muscle growth where muscle fibers are able to split and create new fibers?

The theory of muscle growth that involves the splitting of muscle fibers is known as myofibrillar hypertrophy or fiber hyperplasia. This concept suggests that under certain conditions, such as intense resistance training, existing muscle fibers can split to form new fibers, contributing to overall muscle growth. While hypertrophy primarily results from the increase in the size of existing fibers, there is some debate within the scientific community regarding the extent to which hyperplasia occurs in humans. Most evidence supports that muscle growth primarily occurs through the enlargement of existing fibers rather than the significant formation of new fibers.