Arnold Schwarzenegger goes back to his bodybuilding roots as trailer is released for new docudrama Generation Iron

While Arnold Schwarzenegger was recently the face of California politics, it's his pioneering efforts in bodybuilding that have defined much of his life's work.

So it's fitting that he appears in the upcoming documentary Generation Iron, which follows seven bodybuilders who are gunning for the presitigous title of Mr. Olympia.

It's Arnold's first appearance in a bodybuilding documentary in more than 35 years - 1977's Pumping Iron launched his acting career. 

Passing the torch: Arnold Schwarzenegger raises the hand of current Mr. Olympia Phil Heath in upcoming documentary Generation Iron

Throwback: Arnold won Mr. Olympia in 1970 at the age of 23 - he's still the youngest ever to earn the title

And though Arnold won the international Mr. Olympia contest a staggering seven times, it's current winner Phil Heath who is a main character in the film.

'I think the main motivation for me with bodybuilding is knowing that there's no such thing as a perfect body - but I'm gonna chase it as hard as I can,' Phil says.

A main tension in the narrative, however, seems to be his battle against 2012 Mr. Olympia runner up Kai Greene.

Big ambitions: Kai Greene, who came in second in the 2012 Mr. Olympia contest, hopes to dethrone Phil Heath

All smiles: Phil doesn't seem to mind a little hands-on time with fans

'Phil Heath has had a lot of gifts. Keep your gifts - I work hard,' says Kai Greene.

The film also explores the high-pressure world of bodybuilding in general, addressing the inner workings and misconceptions of the sport - or more accurately, lifestyle. 

'I don't care what kind of scientific formula or whatever it is you come up with, there's no substitute for hard, hard work,' an unseen voice says.

Iron men: Phil and Kai flex their incredible bodies on stage

Men at work: Other bodybuilders in the movie include Branch Warren, Dennis Wolf, Ben Pakulski, Hidetada Yamagishi and Roelly Winklaar

Pumping iron: The film examines the lifestyle of bodybuilding, including athletes' personal backgrounds

'Each man's body will represent years of focus and concentration,' another voice notes.

Generation Iron, which is narrated by Mickey Rourke, features direction from newcomer Vlad Yudin.

'People think all these guys do is take supplements and workout and they are not mentally deep or not smart,' Yudin said to RadarOnline. 'But to follow their regimen, it takes dedication and it takes a smart person to know what to do to their body and bring it to that condition.'

The film opens September 20.

Breaking stereotypes: Kai Greene shows off his talent in painting

What's going on? Kai strips down in public, perhaps for a performance of sorts