A sword, a shield and 299 comrades were all that Gerard Butler needed to hold back the Persian hordes in Zack Snyder’s smash hit 300. It helped of course that those 299 comrades looked like they’d been chiselled out of marble, sporting six packs where most of us carry kegs. In fact so fearsome were the cast’s physiques that many people cried foul, suggesting that they were CGI constructs rather than the result of months of rigorous training. They weren’t of course, this is Sparta after all. Instead they were the result of four months of muscle-building activity where Butler and co spent upwards of 12 hours a day bulking up for their roles.