After three movies in four years, “The Expendables” waited more than nine to unleash its latest adventure, likely a testament to the poorly received youth movement introduced in the third film. “Expend4ables” seeks to provide a badly spelled tonic to that misstep but works from such a flimsy, threadbare script, “The Disposables” would describe it better.

The 2010 movie essentially created as a sort of full-employment act for an older contingent of action stars. Given the meta aspects of that in Hollywood – where aging is almost as dangerous as mercenary work career-wise – the franchise had a semi-refreshing feel, never mind its limited commitment to little matters like plot and story.

Yet even allowing for that, they could have tried a little harder than this. Streamlined to the point of simple-mindedness, the set-up involves a ruthless bad guy (Iko Uwais) who steals a nuclear weapon, forcing everyone’s favorite team of old warhorses to saddle up again, this time with marching orders from a government operative played by Andy Garcia.

Although Barney (Sylvester Stallone) is still the gnarled leader of the group, there’s a fair amount of buddy bonding from the top between him and Lee (Jason Statham), in what amounts to a baton pass in terms of Statham taking point as the centerpiece of the action, having already spent the summer fighting giant prehistoric sharks in “The Meg” sequel.Lee also has a girlfriend, Gina (Megan Fox), who is every bit as deadly as he is, skills that the two use as a form of foreplay. Otherwise, it’s the requisite mix of familiar faces (to “The Expendables,” that is) and new ones, with Dolph Lundgren and Randy Couture joined in the bullpen by Curtis “50 Cent” Jackson, martial-arts star Tony Jaa, Jacob Scipio, and Levy Tran, although most of those characters barely register.

Again rated R after softening the rougher edges the last time, the body count is certainly off-the-charts high, but the action – under the guidance of stunt coordinator-turned-director Scott Waugh (“Need for Speed”) – is about as generic as these things get.

“Gravity’s setting in,” Barney quips when asked, in keeping with the movie’s macho swagger, how it’s hanging.

Allowing for the impact of gravity on one-time action mainstays was ostensibly part of the concept’s initial kick, along with the appearances (some in little more than cameos) of well-known actors, several of whom – wisely, with the benefit of hindsight – sat out this mission.

In theory, it’s hard to keep a franchise like this down, given the equity in the name and ease of plugging new players into the formula. That said, “Expend4bles” sags in more ways than one, and alas, in all the wrong places.