This is a tale of two Wolverines. The first Wolverine, played by 31-year-old Australian actor Hugh Jackman, is an athletic-looking dude. Not huge by any means, he resembles a Championship-level centre-back or a guy you know at work who looks after himself and only comes out drinking once a month.

The second Wolverine, played by 45-year-old Australian actor Hugh Jackman, looks like no one you’ve ever seen in your life. His skin is pulled tight over a slab-like musculature and thick veins coil around shredded forearms. Perched atop the podium of flesh formed by his shoulders and trapezius muscles is his head: tiny, scowling and leathered. 

Wolverine number one existed in the early 2000s and starred in X-Men. Wolverine number two exists rights now and could recently be seen tearing up cinema screens in X-Men: Days of Future Past. Although Wolverine number one was only 14 year ago, by today’s standards he looks hopelessly wrong, like a semi-pro actor called in to play a superhero in a 15-minute, fan-made Youtube short. In 2014 we like our action heroes not just big, but absolutely fucking massive.

Ten years ago action flicks were fronted by Nicolas Cage, Will Smith and Keanu Reeves. Average (if highly charismatic) Joes with whom the audience could just about relate. While it’s true that a decade before that you had Schwarzenegger and Stallone roaming the Earth, men like that were little more than lumbering one-trick ponies of mass destruction. Today’s Hollywood a-list is populated by guys that - unlike Sly and Arnie - possess some pretty serious acting chops. It just so happens that they are also willing and able to pump up their physiques to Fukushima levels of hench-ness.

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A six-pack and a couple of swollen biceps won’t cut it anymore. When Mark Wahlberg, Henry Cavill, Christian Bale and the ever-expanding Jackman sign up to a blockbuster they bust out muscles in places most of us don’t have places. Tom Hardy is a beef sculpture, Gerard Butler a sinewy mass of quivering brawn. The male cast of Fast and Furious individually weigh almost as much as the sports cars in which they cram themselves. We won’t enter a multiplex unless the leading man looks as though he could tear us limb from limb.

The physical transformation of Hollywood’s menfolk does have a dark side. A recent investigation by the Hollywood Reporter discovered that, as well as putting in the hours at the gym, one in five performers were relying on illegal performance-enhancing drugs such as anabolic steroids, testosterone and (most popular of all) human growth hormone to secure those extra inches of pectoral bulk. Vanity Fair went one step further, announcing Hollywood had “gone crazy for human growth hormone”. According to two source, the list of A-list stars injecting the stuff into their stomachs on a regular basis (a habit which costs about $10,000 a year) is considerable. The conclusion was this: any actor around middle age with a ripped six-pack and veiny arms is probably taking HGH.

Unsurprisingly everyone has been at pains to deny wrongdoing. Only Tom Hardy was honest. When a reporter asked him if he’d “juiced” to get his gargantuan physique as seen in Dark Knight Rises, he replied “Nah, it was Smarties. What do you fucking think?”

So what’s going on? Why are actors going to such extreme lengths to get turbo tonk? Would Beverly Hills Cop really have been any better had Eddie Murphy owned shoulders the size of medicine balls? Could we have enjoyed Jurassic Park more had Sam Neil looked capable of punching a velociraptor’s head right off its shoulders?

It may have a lot to do with our changing relationship to fitness. The last decade has seen an unprecedented rise in the number of young men getting into body building. At the last count an estimated 8.7 million Brits had gym membership. Figures from two years ago show UK sales of protein drinks, bars and creatine grew from £73 million to £170 million in just five years. Globally the market for such products is valued at a whopping $4.6 billion. Guys are getting big.

You only need to watch an episode of Sun, Sex And Suspicious Parents or take a summer break to Ibiza to see the evidence. Whereas it was once the case that an average group of British lads consisted of a handful of “normal” young men and one buffed-up gym bunny, nowadays the inverse is true. The Greek and Spanish islands are flooded with tanned traps, lats and triceps.

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If you’re assumption is that the surfeit of creatine-necked blokes means an army of aggressive boneheads looking for a ruck you’d be wrong. In fact our addiction to all things gym-y appears to have chilled us out. NHS reports show violent crime across England and Wales dropping substantially year-on-year for over half a decade. Young men are developing huge muscles but they sure as hell aren’t using them to beat people up.

Perhaps this is because – like most male hobbies – going to the gym is a bit nerdy. We like to obsess over stuff, whether that’s the state of our Panini album, the caliber of strings on our guitar or the number of reps we should be doing to effectively blast our quads. In fact, weight lifting might be the geekiest hobby of all, what with its endless, collectible powders, obscure techniques shared on web forums and tendency to make you spend large swathes of time spent by yourself.

Weight lifting has become a thing that guys do. And as a result the action heroes of 2014 are locked into a literal arms race with their audience, forced to stay one step ahead, developing physiques capable of inspiring awe in normal blokes who are getting bigger all the time. Before Kit Harrington shot this year’s Pompeii he packed on two stone of muscle by undergoing a grueling, five-week, full-time fitness regime, explaining: “It’s an action film, where I’ve got my arms out the whole time… and I’m next to all these stunt boys who are huge, so I need to compete with them.”

And that’s the point. It’s not about screen hunks developing fit bodies for the benefit of swooning girls. Film stars are doing a bazillion stomach crunches a night (as well as allegedly pumping themselves full of dubious substances) to gain the approval of other guys. And if that makes you feel weird, well… do you even lift bro?

Words by Joe Mackertich, follow him on Twitter: @j_mackertich