Final answer:
The Hyperplasia theory is the theory of muscle growth where muscle fibers can split to form new fibers. However, this theory is less established compared to hypertrophy, which involves the enlargement of existing fibers. Muscle contraction is explained by the sliding filament theory, with myosin and actin filaments interacting within the sarcomeres.
Step-by-step explanation:
The theory of muscle growth that suggests muscle fibers are able to split and create new fibers is known as the Hyperplasia theory. This stands in contrast to the hypertrophy theory, which posits that existing muscle fibers increase in size through the increased production of myofibrils and sarcomeres within the fibers, leading to increased mass and bulk. The concept of muscle fibers splitting to form new fibers is still under scientific inquiry and not as widely accepted as hypertrophy.
In the context of the sliding filament theory, muscle contraction occurs when myosin and actin filaments slide past each other within the sarcomeres. This well-accepted explanation involves thick myosin filaments repeatedly pulling on thin actin filaments, utilizing energy from ATP, and resulting in muscle contraction. The number of muscle fibers is genetically set and does not increase, but the amount of myofibrils and sarcomeres within each fiber can increase, resulting in stronger muscles.