How do hormones generally influence muscle growth?

Hormones play a critical role in muscle growth primarily by promoting protein synthesis and aiding recovery after exercise. When hormones such as testosterone, growth hormone, and insulin are released, they stimulate the mechanisms that not only promote the synthesis of new proteins but also support the repair of muscle tissue after physical stress, such as resistance training. This process is essential for muscle hypertrophy, where muscle fibers increase in size as a result of the cumulative effects of repairing damage and building new proteins.

Additionally, hormones can affect other factors like nutrient availability, energy metabolism, and the muscle's overall environment, creating conditions conducive to growth. For example, growth hormone helps regulate energy metabolism and encourages the uptake of amino acids into muscles, while insulin plays a key role in nutrient delivery and storage.

In this context, the other options do not align with the established understanding of hormonal influence on muscle growth. Specifically, hormones do indeed have an effect on muscle growth, not just testosterone, and they are not universally linked to muscle breakdown. The correct answer highlights the crucial roles hormones play in fostering an environment that supports muscle recovery and growth.