Many of Sylvester Stallone’s Hollywood bulk-ups could make this list, but his work for Rambo III is a cut above the rest. Stallone is at his physical peak in this gung-ho, patriotic adventure that takes Rambo into Afghanistan. Stallone worked out up to six days per week, three to four hours per day, to get into the shape he wanted, according to his 1988 TV interview with Oprah Winfrey. Then, to maintain his physique, he’d do three days on, one day off, working for about an hour each session.
Another reason why Stallone was so jacked in this film? Chalk it up to his professional rivalry with Arnold Schwarzenegger. As Schwarzenegger recounted in an interview at Beyond Fest in 2017, the two stars constantly were trying to one-up each other in their movies: “I’m so glad we straightened out our mess because it wasn’t pretty,” Schwarzenegger said. “We were attacking each other in the press relentlessly. We called each other names and called out our weak points, and it was so competitive. It became so silly that all of a sudden it became a competition about who has the most muscular body. So I said, ‘Sly, forget about that now. Because there’s only one seven-time Mr. Olympia, and it’s me!’ But then he had to use bigger weapons. So then it was a competition of who had the biggest gun, and then who uses the biggest knife. Do you remember the Rambo knife became so big it was like a sword? No one has a knife like that! But Stallone had one built, so I had to come in with a bigger one. This is how it went. 'Who has the most unique killings? Who kills more people on screen? Who makes more money at the box office? Who has less body fat when he goes into production?' All of this shit started happening, and it didn’t stop. It was unbelievable.”
(Want to get jacked like Stallone? Try Stallone's full arms routine and this workout on how to get forearms like Rambo.)