What adaptation occurs in muscle tissues from regular resistance training?

Regular resistance training leads to a process known as hypertrophy, which is the increase in the size of skeletal muscle fibers. This adaptation occurs as a response to the stresses placed on the muscles during training, prompting the body to repair and build new muscle tissue. The key mechanisms behind hypertrophy include an increase in the synthesis of proteins within the muscle, as well as the recruitment of satellite cells that contribute to muscle fiber growth.

As muscles are exposed to progressively heavier loads, they adapt not only by enlarging existing muscle fibers but also potentially by increasing the number of fibers through the activation of these satellite cells. This results in greater strength and endurance, allowing the individual to perform better during physical activities.

In contrast, muscle atrophy refers to a decrease in muscle size, which is not a response to regular resistance training. Significant changes, such as hypertrophy, would not be described as "no significant change," and while resistance training can improve muscular flexibility to some extent, the primary adaptation is increase in muscle size rather than flexibility.