As he was training to accomplish a 600 pound(!) bench press, Chuck used to train using a variety of techniques involving heavy supports and negatives — he even had a special handle welded to the underside of his pickup truck which he used to lift and support the whole affair.
Sipes would first lift the pickup truck as high as he could with his arms then wedge his legs underneath. In the top position, he estimated that he was supporting 1600 pounds.
Demonstrating is IFBB Mr. America, Mr. Universe and Mr. World, Chuck Sipes, who was clearly no stranger to forearm work.