subject: How to Bulk Up For the Beach [print this page] Lastly, recovery is vital for muscle buildingLastly, recovery is vital for muscle building. You actually build more muscle outside the gym than when you're working out. This is because while you're working out you actually cause microtrauma to the muscle tissue. When you're resting the body then heals the microtrauma by creating more fibres resulting in an increase in muscle size. Hormones that are released when you're sleeping include IGF-1 (Insulin-like Growth Factor 1), Melatonin and HGH (Human Growth Hormone).
