Deca Durabolin is a brand name for a type of steroids, Nandrolone Decanoate, that can be injected. They were first available as a prescription drug in 1962. Deca Durabolin cycles are cycles where these drugs are taken.
They are steroid regimens based on the steroid Deca Durabolin. They are"cycles" because the dosage fluctuates based on the taker's desire to achieve maximum effect with minimal side effects.