When Madonna wore her pointy-bra bodysuits onstage, circa 1990, the costumes were so outside the realm of normal human activity that they raised the question: Who but Madonna would wear such a thing? Likewise, when metallic leggings that made models look like the “Star Wars” droid C-3PO showed up at Balenciaga, it was fair to wonder: What’s the point?

The Metropolitan Museum of Art’s Costume Institute offers an answer: Its new exhibit, “Superheroes: Fashion and Fantasy,” which opens Wednesday, draws a connection between the garments made for comic book heroes and the sometimes inexplicable fashion that comes down the runway. These concepts may seem disparate and, to some degree, random. But the theme unlocks some of the mysteries of fashion — especially its outré, outrageous aspects.

On one level, the connection is straightforward: “Fashion mirrors the comic book’s obsessive preoccupation with the ideal body, signaling changes in prevailing standards of perfection,” according to the exhibition text.

But from there, flights of fancy, excitement, and wild imagination ensue. “Fashion, like the superhero, celebrates metamorphosis, providing unlimited opportunities to remake and reshape the flesh and the self. It offers entrance into another world, a world of grandiose posturings and unfettered imagings.”

After all, if your job were to protect the earth, what would you wear? The exhibit contains several costumes used by television and film stars who have borne such important burdens. Lynda Carter’s “Wonder Woman” outfit (1976) is here, as is Christopher Reeve’s “Superman” costume (1978) and Robert Downey Jr.’s full-body armor from the recently released “Iron Man” (2008).

But say you were going to a party — in real life, in Manhattan — knowing that you couldn’t save the earth, but feeling indestructible all the same? What would you wear to communicate your confidence? The show contains plenty of finery for such a mood: a pink plastic dress by Hussein Chalayan; a sweat suit made of a fabric printed with bricks; a strappy black bodysuit with a corseted back from Dolce & Gabbana.

Not every piece in the show seems to have been inspired by superheroes, but what the thematic presentation suggests is how designers’ ideas are rooted in something other than their own visions. Each bay of the exhibit explores one aspect of the metaphors inherent in superhero costumes, such as “The Armored Body,” “The Patriotic Body,” and “The Mutant Body.” The show is heavily weighted toward designers who experiment with extreme creativity: John Galliano, Jean Paul Gaultier, Alexander McQueen, Bernhard Willhelm, and Thierry Mugler.

The displays offer exciting visual pairings, the most effective of which, “The Graphic Body II,” centers around Spiderman. Shown here is Tobey Maguire’s costume from “Spider-Man 3” (2007), as well as a full-body racing suit, designed by Spyder Active Sports and complete with a web motif. On the fashion end are beautiful gowns with sweeping spider web motifs by Giorgio Armani and John Galliano. These items have nothing in common on a functional level, but the presentation gives us a way of thinking about the things that appear in our material world and why they do.

One smaller aspect of this show that is nevertheless fascinating is the inclusion of performance technology. In several displays, but especially in “The Aerodynamic Body,” are unitards for racing, made by athletic wear brands such as Descente and Speedo. These body-hugging second skins are the closest thing to the fantasy of a super-being, one that can move so fast that special clothing is needed. We know that the superhero costumes pictured in comic books were inspired by strongmen and circus performers, but here, the inspiration seems to flow in reverse: Descente’s hooded muscle suit for the Canadian speed skating team looks an awful lot like the Flash’s red bodysuit.

To be sure, there is another, less amusing aspect of this exhibit that must be raised. What are superhero costumes and track suits doing at the Metropolitan Museum of Art? The trivial nature of comic book heroes appears incongruous with this particular museum.

Be that as it may, this exhibit encourages more creative thinking on the part of the viewer than the Costume Institute’s two previous shows: “blog.mode,” in which objects from the collection were displayed and then discussed on a museum blog, and “Poiret: King of Fashion” a retrospective of designer Paul Poiret’s life and work. Looking at pretty objects in those exhibits was fascinating and educative. The superheroes exhibit, perhaps counterintuitively, asks more of viewer. It uncovers connections and ideas that may have otherwise not been explored in public. And the bottom line is that no other museum has the resources to do this type of exhibit better. (Though if I were in the driver’s seat, I would have used those resources to include Madonna’s pointy bras, which are a glaring omission.)

“Superheroes: Fashion and Fantasy” leads the way in serious scrutiny of popular culture, which — like it or not — is the art of the day.