Which two hormones among the following are known to enhance skeletal muscle growth?

Which two hormones among the following are known to enhance skeletal muscle growth?

• A. Growth Hormone and IGF-1
• B. Cortisol and Progesterone
• C. Growth Hormone and Cortisol
• D. IGF-1 and Progesterone

Answer: (A)

The key idea is which hormones actively stimulate skeletal muscle growth. Growth hormone sets the stage by increasing production of IGF-1 (especially in liver and muscle). IGF-1 then acts directly on muscle tissue to stimulate protein synthesis and satellite cell activation, driving muscle fiber growth and hypertrophy. In practice, the anabolic effects of growth hormone are largely carried out through IGF-1, with IGF-1 also working locally in muscle to promote growth even when GH signaling is limited. Cortisol is mainly catabolic, promoting protein breakdown, and progesterone does not drive skeletal muscle hypertrophy in the way GH and IGF-1 do. Therefore, the combination of growth hormone and IGF-1 best explains enhanced skeletal muscle growth.

The key idea is which hormones actively stimulate skeletal muscle growth. Growth hormone sets the stage by increasing production of IGF-1 (especially in liver and muscle). IGF-1 then acts directly on muscle tissue to stimulate protein synthesis and satellite cell activation, driving muscle fiber growth and hypertrophy. In practice, the anabolic effects of growth hormone are largely carried out through IGF-1, with IGF-1 also working locally in muscle to promote growth even when GH signaling is limited. Cortisol is mainly catabolic, promoting protein breakdown, and progesterone does not drive skeletal muscle hypertrophy in the way GH and IGF-1 do. Therefore, the combination of growth hormone and IGF-1 best explains enhanced skeletal muscle growth.