Hollywood action star Sylvester Stallone has rubbished rumours he took steroids in preparation for his role as Rambo - but admits bulking up with the help of human growth hormones. The Rocky star used prescription testosterone to gain extra muscle for the new movie about the Vietnam veteran - due for release next month (Feb08) - believing the hormone keeps him in shape as he gets older. The 61-year-old actor says, "HGH (human growth hormone) is nothing. Anyone who calls it a steroid is grossly misinformed. "Everyone over 40-years-old would be wise to investigate it because it increases the quality of your life. Mark my words, in 10 years, it will be over the counter." The new Rambo movie follows the successful revival of Stallone's hugely popular Rocky movie series - which brought the star out of retirement in 2006. In March 2007, Stallone was charged with illegally importing hormones into Australia after they were found in his personal luggage at Sydney airport - leading customs to later search his hotel room, where 48 vials of testosterone were found.