What is the principal male hormone responsible for muscle growth?

Testosterone is the principal male hormone that plays a crucial role in muscle growth and development. It is an anabolic steroid hormone produced primarily in the testes, with smaller amounts produced in the adrenal glands. Testosterone promotes muscle protein synthesis, which is essential for muscle hypertrophy, or the increase in muscle size. It also enhances strength and overall physical performance by aiding in the recovery and repair of muscle tissue following exercise.

Additionally, testosterone influences the distribution of body fat and contributes to the overall increase in muscle mass by stimulating the production of growth factors like IGF-1 (Insulin-like Growth Factor 1). This hormone plays a significant role in the body’s metabolic functions, further facilitating an environment conducive to muscle building.

While estrogen, insulin, and cortisol have their respective roles in the body—such as regulating fat distribution, glucose metabolism, and stress response—none possess the same direct anabolic effects on muscle tissue as testosterone does. Thus, testosterone is recognized as the key hormone for promoting muscle growth and is therefore the correct answer.