During the dark days of the early 1940s, a covert U.S. Military experiment turned Steve Rogers into America's first Super-Soldier, Captain America. Throughout the war, Cap and his partner, Bucky fought alongside infantry and with a group of heroes known as the Invaders. In the closing months of World War II, Captain America and Bucky were both presumed dead in an explosion. Decades later, Captain America was found trapped in ice and revived in the modern world. Captain America would then later go on to be one of the most important members of the Avengers as well as a leader of the team.
Super-Soldier Serum[]
The serum made Steve Rogers gain the physique of an Olympic athlete, which can be compared to an athlete of any modality. The plot in the comics was lost on the formula of the serum, and several attempts were made to create a serum capable of making someone with strength, speed and stamina equal to the captain's. These attempts will give rise to several Marvel characters. In the MCU, Hulk is one of those characters, this was to make the idea of Banner surviving radiation more logical. Coulson states that he thought radiation would be the key to understanding the serum.