Since last year, Amay Sheth, a 26-year-old start-up founder in Greenwich Village, Manhattan, has been scheming to shave time off his visits to his parents in Westchester County — and going less often. The reason: He can’t wait to get home to his Tonal, a $2,995 smart strength-training device that packs a weight room’s worth of equipment in one machine that’s the size of a poster.

“I hate being apart from it,” said Mr. Sheth, who is, he admits, somewhat obsessed with constantly smashing his strength score, which rises if he lifts a bit heavier or does more reps. So obsessed that he recently bought a second Tonal for his parents’ house, though there’s an 11-week wait for delivery.

If that sounds like the scramble for Peloton, the internet-connected stationary bike that’s. been a runaway sensation in the pandemic, that’s exactly what Tonal and its competitors are hoping for: To make at-home strength training as wildly popular as Peloton, and to a lesser extent the gym portal Mirror, has made cardio. (Both of those companies offer strength training, but it is not their focus.)

And while there are tens of millions of unemployed Americans, some are still shelling out thousands of dollars for home fitness equipment.

These would-be barbell juggernauts have some heavy lifting to do, though. Strength training has always had its adherents, but it has never achieved the mass boy-band fan-like devotion of cardio forms like Jazzercise, Tae Bo, and more recently, spinning. A 2016 National Health Interview Survey, the most recent year available, found roughly half the population meets the Centers for Disease Control and Prevention’s standard for aerobic exercise (150 minutes per week) but just 21.9 percent of women and 30 percent of men meet guidelines for “muscle strengthening” (two sessions per week.)

Weight rooms can be intimidating, with little intuitive about the equipment, of which lifting at home can require a fairly daunting array. Nor does it help that aerobic exercise is considered the gold standard for calorie burning. Some women seeking to slim erroneously fear that lifting will cause bulk, but actually the more muscle you have, the more calories you burn, said Michele Olson, a senior clinical professor of sport science at Alabama’s Huntingdon College, and a fellow of the American College of Sports Medicine.

By doing cardio “most of us feel we’ve checked off our fitness for the day or week,” Dr. Olson said.

One big advance of this new breed of devices is that, through a combination of artificial intelligence, cameras, and motion sensors, they can actually teach you how to lift. They monitor your speed, telling you to “lower yourself down slower, and with control” during those curtsy lunges you tried to blast through, and point out errors in your form like “your knees are over your toes” for a squat — a far cry from dumbbells, even if yours are the $2,860 pair recently offered by Louis Vuitton.

Dumbbells haven’t evolved much since the early 18th century, said Jan Todd, a professor in the department of kinesiology and health education at the University of Texas-Austin, who wrote a paper on their history. They were “dumb” — as in soundless — bells on which church bell ringers practiced to build the serious upper body strength required to coax a full peal out of a heavy iron medieval bell. (Bowflex, the veteran home gym brand, briefly sold a $549 pair of dumbbells that would track your weight and reps via Bluetooth. It’s no longer made.)

Personal training is integral to all the machines: Tonal, Tempo, which came to market in February priced at $1,995, and Forme Life, which starts shipping late this year and costs $4,295.

“We’ve been running and cycling since we were kids, and when you take a studio class the teachers are usually there to motivate us more than teach us,” said Aly Orady, 42, the founder of Tonal. “But strength training is actually really, really hard. That’s why personal trainers have jobs.”

Moawia Eldeeb, the 27-year-old founder of Tempo and a certified personal trainer, said his machine is an improvement on a trainer at the gym because of the data it offers.

“Before you can lift another five pounds, there’s a lot of interesting data points that happen on the journey,” said Mr. Eldeeb, who was formerly homeless and now credits the coaches at the local Y.M.C.A. in Harlem, blocks from a shelter where he stayed, with pulling him away from the Ping-Pong table there and training him for free.

Instead of someone telling you simply that your form looks better, Tempo — a free-standing easel-shaped cabinet with a 42-inch screen — may show you, say, exactly how much deeper your squat has become. (The cabinet stores the weighted plates, which are delivered in 10 boxes, none weighing more than 10 pounds, lest you need to spend months training just to be able to assemble the thing.) Tonal is a screen with weighted cables tucked behind it; because it uses electromagnetic resistance, not physical weights, to generate force, it can act as a spotter, automatically decreasing weight when it senses a user is struggling.

Nearly 50 percent of buyers are women, the founders say. And buyers of these devices, at least so far, seem to be people who already know how to lift weights, not (or not yet) people who first want to learn.

“The Tonal paid for itself in four months,” said Joina Liao, 43, of San Francisco. Ms. Liao said her results from her personal trainer, who charged $100 per session, were limited by how often she could afford him, but she can do Tonal sessions four times a week.

Ms. Liao has had a Peloton bike since 2015, but has ignored it since she bought the Tonal.

“If you take a dumbbell class in Peloton you pick up the same weight as you’ve always done,” she said. “With the AI in Tonal once you do two sets, it goes up in one-pound increments. It really pushes you to improve without you putting much thought into it.”

Niket Desai, 33, who works at an automated timesheet start-up in San Francisco, bought a Tempo in January after he realized he was spending $10,000 a year on Barry’s Bootcamp classes, if you also add in the $10 smoothie he ordered after every workout. He briefly debated a Peloton bike — “I saw six delivered on my street in one day,” he said — but decided he could motivate himself to do cardio; he needed some help with the weight training.

He rated the Tempo classes and challenges as “eighty percent of the quality of Barry’s at one tenth of the cost.” At least six of his friends have now bought one; he said seeing their faces on the leader board and watching their rep counts and weight counts go up spurs him to use the machine.

Mr. Desai lives in a small apartment; the Tempo cabinet takes up a chunk of his living room, but its design, he said, “makes it look like it belongs there.” Tonal and Forme — which look like a big screen and a mirror, respectively — also don’t scream “gym.”

Some hard-core strength training communities are likely to be suspicious; Natalia Mehlman Petrzela, a fitness historian and associate professor at The New School, wrote that she has repeatedly found they think the only “real” way to lift is with old-school barbells and kettlebells, and that innovations “are somehow weaker versions of that authentic experience.”

Mr. Orady said he does not like to talk about the pro facilities where the machine has been installed, because he’d prefer to promote it for home use, but there is one at the Minnesota Timberwolves’ gym. The company has raised $90 million, he said, including from more than 12 athlete-investors such as Serena Williams, Klay Thompson of the Golden State Warriors, and N.F.L. Hall of Famer Tony Gonzalez, the last of whom was sold when he visited the company’s offices and did a rotational lift, an explosive movement where you swing a weighted cable from knee level up over the opposite shoulder.

The machine, Mr. Gonzalez said, is his only home strength-training equipment except for a kettlebell, and that is now mostly for stretching.

Tempo, which has only been on the market for almost six months, has some catching up to do, though the company recently announced it had closed a $60 million round of funding, for a total of $77 million.

Trent Ward, 39, a founder of Forme with the Swiss designer Yves Behar, said he wasn’t worried about being too late to the market, like SoulCycle’s much delayed at-home bike. Forme is directed at wealthy people in the suburbs, who might already have a Peloton, have room for more equipment and might be willing to pay extra for regular live on-screen personal training sessions.

One thing Mr. Ward has struggled with is what to call the exercises, which he thinks are part of strength training’s marketing problem. “They sound so lame. Who wants to do a Romanian dead lift or a face pull? And ‘guns and buns’ and cheesy names just turn people off.” Mr. Ward has settled for showing the exercise name, but in a way it can be hidden.

“People don’t care about learning the name,” he said. “They just want the results.”