When filming Rocky IV, Dolph Lundgren punched Sylvester Stallone so hard that he had to be hospitalized!

Someone must've taken the line "I must break you" a bit too seriously...While shooting the climatic scene for the third Rocky sequel, Stallone (who also wrote and directed the movie) decided to increase the fight’s realism by ACTUALLY trading punches with Lundgren. After three takes involving several jabs to his ribs, Sly felt a minor burning sensation in his chest, but decided to ignore it. Later that night, Stallone had trouble breathing and was taken to the local emergency room. There, they found that his systolic blood pressure had soared to above 200! (somewhere around 120 is normal).

The action star was immediately life-flighted from Canada to St. John’s Hospital in Santa Monica, CA, where he remained in intensive care for eight days. So what exactly had happened? Slyvester’s co-star had punched him in the chest so hard that his heart had collided with his sternum! The impact had caused his heart to swell, which restricted blood flow throughout his body and made it difficult for him to breathe.