For Sylvester Stallone, a film is only as good as the injuries or risks that accompany the making of it.

"Usually, I grade the quality of a film by the intensity of the injury. Like if I do Stop Or My Mom Will Shoot, I never get hurt. But if I do Rambo or The Expendables I break my neck, I break my spine, or I dislocate both shoulders. But I think, 'this is going to be a great movie'."

On The Expendables 3, the latest in his action icon-packed franchise which opens in cinemas next week, he ended up taking a big fall on his back. "So, I've had to have some metal put in there. If I end up squeaking, it's not my shoes, it's my back!"

Such humour is indicative of the way Stallone now treats his interviews and his career. As a result, he is always entertaining company. He never shies away from a good anecdote and can easily identify the high points of a career that has included three Oscar wins for the first Rocky (including best picture), further critical acclaim for First Blood (the first Rambo instalment), and Copland (alongside Robert De Niro and Harvey Keitel) as well as a stint as one of the biggest box-office stars of the 1980s and early 1990s. Yet most of his own highlights involve some form of close shave with death.

"I've fallen through trees in First Blood and been wiped out on the bottom branches. And I'm really proud of Rambo 3 because there was no CGI, so, firstly, we almost got hit by the helicopters when we were on horse-back and, secondly, we actually played the Buzkashi... a real Afghan game where you play with the body of a dead sheep. Or hanging from those rocks in Cliffhanger was amazing because I hate heights. It's 4,000 feet and you're going, 'how did they talk me into this? I don't even like being in cowboy boots!'

"But overall I would say dealing with Dolph Lundgren in Rocky IV - that was brutal, I mean really brutal. He was so unbelievably proud, it's hard to describe. But he almost killed me [Stallone was in intensive care for eight days after one punch to the chest]. The idea of sustaining a 15-round fight scene, which took six months, I'm really proud of that one because I know I could never do it again."

He may now be 68 and aware of some limitations, but Stallone shows no sign of taking things easy and remains as excited as ever about future film projects, especially if they are Expendables-related.

An all-female Expenda-belle picture is in the works ("we don't want to create something that's just making use of the name; we want it to be something that would hold its own"), while the decision to use an even bigger cast, including Oscar-calibre actors and younger mixed martial arts stars, on Expendables 3 is designed to secure a greater longevity for the franchise.

"I felt we had reached a point where we needed to upgrade and retool and bring in actors that are known for their physicality but who are also incredibly dramatic actors, nominated actors, actors that have done film roles in every genre. I thought that would be interesting. Also, the age factor is that youth must be served. So, we brought in the new generation.

"For example, [martial artist] Ronda Rousey - there was debate about her of the nature that 'Ronda's not really an actor, she's a fighter'. But I said that she's a new kind of entertainer and I couldn't have been luckier or more right because this girl is one of a kind. She's very sexy but she also can tie you into a knot. She's still raw and learning on the job but I think we've got something special. It's the same with Victor Ortiz, who is a real world champion [boxer]. I don't think this film could have been accomplished if it was just all actors; there are some skills on show that take an entire lifetime to learn and that's what we were blessed with by getting to employ those skills."

And what of those more established character actors such as Mel Gibson, who plays the main villain? Did he take much convincing? "Originally, I wanted Mel to direct because he's such a great director. But everything is so personal that it has to come from him. So, instead he said, 'I wouldn't mind playing the villain'. And I was like [bangs the table], 'sold!'

"But it means that we have so many opportunities with The Expendables now because it's not just about attracting athletic actors... there's an opportunity for real actors to add different things. It means we can advance this more and more."

And that, according to Stallone, involves at least two more adventures.

The Expendables 3 opens in cinemas on Thursday, August 14 .