Muscle growth needs androgen, which comes from three elements, pituitary, adrenaline and testosterone. Testosterone is very important, so everyone will squat, which is the only magic weapon to stimulate testosterone. If you row a boat, your muscles will grow slowly. If it does not reach 30, the estimated frequency will not have much impact. It varies from person to person. Many boys will be in two States after 35, and some will be in the morning after 45.