Sly puts Rambo back in action

'My T-shirt's too tight, I'm trying to stretch it," says Sylvester Stallone as he enters the room, pulling at the sleeves of his under-strain top. It's little wonder it's a snug fit, really, considering his biceps are the size of most people's thighs.

As he takes to his chair, it is easy to forget 'Sly' is 61 years old, and it's even easier once you've seen him skipping over logs, running through steamy jungle and despatching enemy soldiers with ease in his latest film Rambo.

"I'm telling you, we're a lot tougher than you think," he explains. "The difference is, I'm lucky because I'm under the gun and under pressure to perform. If I didn't have this goal, believe me, I'd be more than happy to sit at home, throw 25 croissants down my throat and finish it off with a pint of beer.

"When I was on my way to start filming, I was 18-20 kilos heavier than I am now, I was huge, massive, but I knew I had to put that weight on because of the heat and everything else.

"It's all goal orientated, if you don't have a goal, it's very, very, very hard to just stay in shape.

"But in this business, I've been identified as having a certain kind of physicality and style. For me to expect to be Daniel Day-Lewis or Russell Crowe would be futile. I don't do what they do, and they don't do what I do, and it took me many years to figure that out. You can't do everything, we have specialities, and there are things that you look like a total fool doing."

The fourth instalment in the series, this new film comes 20 years after Rambo III – a film Sly's less then proud of. So why resurrect the character?

He says: "I thought that it might be an interesting revisit today, because an entire generation has not seen Rambo. They probably think he's someone's granddad. I wanted them to see the old school, mythic, meet-you-at-High-Noon, modern western. It's savage, and the biggest savage wins."

The new movie finds Vietnam veteran and one-man army Rambo living a quiet life in deepest Thailand, near the Burmese border. He has turned his back on the military and gets by catching snakes for money, while also doing a spot of fishing with his trusty bow and arrow.

When a band of American missionaries are taken hostage by a ruthless and sadistic army colonel and his soldiers, Rambo leads a group of mercenaries in a violent rescue mission into the war zone.

The film is gritty, the bloodiest of all the Rambo franchise and is set in a real-life conflict – Burma's bloody civil war has waged since the country came under military rule in 1962.

It has an extra resonance, thanks to the opening segment featuring newsreel from last year's events, with the military crushing peaceful dissent led by Buddhist monks. Depend-ing on which reports you read, hundreds or thousands of protesters were killed.

Knowing what a political hotbed it was, Stallone – who also wrote, directed and co-produced the film – was reluctant to attempt the project without doing the necessary research.

"We were told by students who had contacted the Free Burma Rangers in Thailand that the film provided . . . I'm reluctant to use the word enjoyment, let's say a pleasure that they can finally have something out there showing what's going on, that isn't the stale news, and that it will be seen around the world.

"Rambo says the line 'live for nothing, die for something' in the film, and the students are now using it, they've hooked onto that phrase. The one thing they did say is that, as horrific and bloody as you might think the film is, it doesn't compare to what the people have been through."

In parts, this is one of the most violent movies I've seen, but the New York-born actor is quick to defend his decision to include graphic images.

"That's what war is," he says. "Gratuitous violence is a guy dressed in a fright wig chasing ten teenagers around a forest. This is war, and civil war is by far the most vicious of all."

There is nothing light-hearted about Rambo, but if the viewing experience is a turbulent ride, it's nothing compared to what the actors and crew were going through off-screen.

"The Burmese police are insidious and work up and down the river near where we were. They certainly made their presence known.

"It was a very dangerous place. I wondered if there was anything around there that was nice. Even the butterflies were deadly. The biggest problem were the snakes, or maybe the centipedes which were about a foot long!

"It was a tense situation, and a very difficult film to make, but I'm glad we did it there, and I'm so glad we got so many Burmese to be in the film. They were terrified, absolutely terrified of being in the film."

The life and times of Sylvester Stallone

Name: Sylvester Gardenzia Stallone

Age: 61

Significant other: Married to third wife Jennifer Flavin, they have three children. Stallone has two children from his first marriage.

Career high: Writing and starring in Rocky, which went on to win three Oscars and a further seven Academy nominations in 1977.

Career low: 1992's awful comedy Stop Or My Mom Will Shoot.

Famous for: His bulging physique

Words of wisdom: "The biggest mistake I ever made was the sloppy handling of Judge Dredd. I thought that could have been a fantastic, nihilistic, interesting vision of the future which showed how far pop culture had come. That film really bothered me a great deal."