Vintage Tunturi exercise bikes—those mod, elongated Finnish machines—have surfaced on Instagram, at the very least as fashionable props. And some gear makers have evolved, transcending their late-night cable pasts. (Shakeweights, with very rare exceptions, do not seem ever to have escaped meme-punchline territory.)

Famous in the 1980s for its ski machines, NordicTrack’s treadmills, ellipticals, and cycles now make up the bulk of its sales, and the Classic Pro Skier is not even displayed on the company’s homepage. Nor is Bowflex a joke; it’s part of gym-equipment giant Nautilus. (Neither company has data on whether customers from long ago have made recent inquiries about resuscitating vintage devices.)

Soloflex remains in a liminal state, not fully embraced by the mainstream, but still beloved by a core group of serious muscle-builders. Whether they’ve purchased new machines or dusted off decades-old ones, they enthuse about the ease of setup, the solid construction, and even the appearance.

“It looks like a piece of Danish modern furniture,” says Marion Roach Smith, a writer and memoir coach whose home gym, in Troy, N.Y., includes not only a 1978 Soloflex but also a 1984 Precor rowing machine.

Very little is apparently needed to resuscitate an ancient Soloflex—often just new resistance bands, which tend to degrade over the decades. Privé Fitness, which makes replacement bands for Soloflex, Body by Jake, and Weider machines, says March and April have seen a 211% increase in band sales over the same period last year.

Often, the Soloflex fans are older, and they appreciate the way resistance-band workouts are suited to aging bodies. “You get banged up through life,” one wrote on the Soloflex Corner, a Facebook group. “Soloflex can provide a good platform to lift heavy without dealing with the weights.”

The older generation’s enthusiasm may now get passed down to a younger one: When the country started going on lockdown, Steve Ockerman’s son, Will—a Division 1 tennis player at the U.S. Military Academy at West Point—came home to North Carolina.  At first, Will said, “I was kind of struggling, figuring out what to do” for exercise. Then his father texted. “He was, like, ‘I'm gonna pull this Soloflex out!’”

“I had no idea what he was talking about,” the 22-year-old Will admits.

When Will saw the machine, he was skeptical, but then he tried it—and discovered its versatility. He could do bench presses, lat pulldowns, shoulder presses, even squats. “Every time I come back to my parents’ house,” he said. “I'm sure I'll hop on it and get back to the basics.” (Boomers, take heed: Never, ever throw anything away.)

Some of these purchases aren’t even as old as you’d think: Allison Robicelli bought a ThighMaster about a year and a half ago. The squeezable, bent metal tube has been sold since 1990, by former Three’s Company star Suzanne Somers. (Successfully, too: Total sales reportedly surpass $100 million.) The device was not for herself, Robicelli says, but for her then-10-year-old son, who wanted to start exercising. Of course, it wound up “stashed in the corner.”