In a rented home on a sunny street in Los Angeles, a team of professional gamers sat hunched over in swivel chairs while a pair of ergonomic specialists observed their posture, asked questions and took notes.

The gamers reported pain in their necks, their lower backs, their hips, wrists and shoulders. Carpal tunnel was a common complaint. Most of them were not yet 20.

Over several days in May 2018, specialists who had come from Herman Miller, the modern furniture company, and Logitech, the computer accessory and software manufacturer, watched professional teams practice in their training facilities (often large homes they shared with teammates) and play in a tournament.

They noticed how the gamers gripped their toes on the bases of their chairs to support their bodies, how they would incline forward when they played and how, in their downtime, they would exhibit what Herman Miller personnel dubbed “the teenage slouch.”

“We’re over 50, we don’t know anything about gaming,” said John Aldrich, the vice president of advanced engineering at Herman Miller, which is best known for its Eames lounge chair and mid-century modern furniture. “Watching multimillionaire 19-year-olds playing games was not what I expected to do with my career.”

Perhaps not, but Mr. Aldrich has devoted much of his professional life to ergonomic design, an area of relevance to anyone who sits for extended periods of time, as gamers do. And many players gravitate toward models that resemble chunkier, aggressively colorful office chairs.

Gaming-specific chairs have become unusually coveted during a pandemic that has made both sitting and gaming common occupations. From March to mid-May, Amazon saw a more than 300 percent increase in sales of gaming chairs. Overall video game spending in the United States hit a 10-year peak in June, according to a report from the NPD Group, a market research firm.

Which is to say, whether they knew it or not, the ergonomic specialists had a very good problem on their hands.

The Occupational Hazards of Gaming

It’s not unusual for a professional gamer to sit for 13 hours at a time. And during busy tournament seasons, there are many weeks where teams don’t take a day off from practice, said Noah Francis, a 22-year-old professional Counter-Strike player for Team Envy, who went pro at age 15 and goes by the name “Nifty.”

Carpal tunnel, arthritis, chronic pain and repetitive strain injuries frequently result from sustained sitting and gameplay. “Nerd neck” and “keyboard arm” are terms that are tossed around often.

“People shake off back pain like, ‘Ah, I’ve been sitting for a long time,’” Mr. Francis said. “It’s actually not normal to have back pain at such a young age — you shouldn’t have it for another 20 years at least.”

Some players rely on massage therapists and chiropractors, and elite teams often travel with physical therapists. They also have personal trainers and “mental trainers,” a term that seemed to apply broadly to sports psychologists, performance specialists and general talk therapists.

Professional gaming is a sport, and the attention devoted to its players’ health is not unusual. Still, the specific ailments sound a bit geriatric for a field that skews so young. Though the average age of competitive players varies from game to game, the oldest person in the North America League of Legends Championship Series is 28. The champion of last year’s first Fortnite World Cup was 16.

“I guess I could compare it to some modeling or pro sports careers — like late 20s to early 30s is when your pro days are behind you,” said Nate Hill, a 25-year-old Fortnite player for FaZe Clan.

Mr. Hill has been gaming for as long as he can remember. “Perpetual neck pain and back pain and hands and wrists — they just come with the job,” he said.

Though concerns about occupational health span professions, the needs differ from one to the next. Where a white-collar office worker may sit back in a desk chair, a gamer will sit more upright, tilted forward, often at the edge of a chair.

Justin Young, an associate professor of industrial and manufacturing engineering at Kettering University, described professional esports players as “power office users.” This basically translates to anyone who spends most of the day sedentary in front of a computer, often in positions that lead to physical ailments.

“It takes a while to develop damage, but a lot of people are on their way,” Mr. Young said. “Neck pain, shoulder pain, low back pain, wrists — you want to prevent it in the first place before it sticks with you.”

The chair is “an essential component” for body support, said Michelle Robertson, a lecturer at Northeastern University and the director of the Office Ergonomics Research Committee. A good chair, she said, is one that has adjustable features and arm rests, supports the spine and has a seat that tilts. It eases the strain on the muscles that support the body when someone sits for prolonged periods of time.

“Whether you’re in the office or gaming, you’re trying to support the body,” Ms. Robertson said. Office workers, animators, accountants — they all have this in common with gamers.

The Gamer Chair/Desk Chair Nexus

There is no definitive definition of what makes a gamer chair, but explanations share some common threads: They are inspired by racecar seats, and they tend to be flashy. They come in loud colors and are heavily branded (sometimes with superheroes, and there seems to be a niche devoted to baby pink chairs featuring bunnies).

The first gaming chair was invented by “some bloke who bolted a racing chair onto an office wheelbase,” said Vincent Sin, the head of industrial design at Secretlab, a gaming chair company founded in 2014.

The company DXRacer — originally a manufacturer of seats for sports cars — is often credited with putting the the first modern gaming chair on the market in 2006, when it combined a racecar seat with an office chair base. Others quickly followed suit.

“It became so popular because gamers can relate to racing car drivers quite a lot — sitting in a chair for long hours, needing proper endurance,” Mr. Sin said. “It gave a good fundamental architecture for a good sitting experience.”

Authentic gaming chairs mimic the design of automotive sports seats, said Scott Richards, the president of AKRacing’s North American operations, another gaming chair company. They have side bolsters to support legs for long drives and a form-fitting backrest to support the neck and spine. Where office chairs are often made of mesh, gaming chairs are made of foam and leather (or polyurethane leather). Models can run between $100 and $800.

There are lots of copycats on the market. “A lot of so-called gaming chairs out there are just an office chair with a patch of bright red P.U. leather sewn on,” said Mr. Richards.

The designers at Herman Miller opted for a more minimal style, one that reflected the way the gamers dressed and presented themselves. (“I had to go out and learn what a Yeezy was,” Mr. Aldrich said.)

“Historically, gaming has an in-your-face design aesthetic: vibrant colors, aggressive, quite masculine,” said Peter Kingsley, the chief marketing officer of Logitech’s gaming wing. The chair also has a steep Herman Miller price tag, at $1,495.

Mr. Richards recalled the day he heard the news that Herman Miller would be entering the gaming chair market with Logitech. “I got a lot of emails from people like, ‘Look at this, Herman Miller is coming after us, we’re freaking out,’” he said. “I was like, ‘They’ll do what they do, we’ll focus on what we do.’”

“The whole gaming scene is big business now,” Mr. Richards continued. In the beginning, he said, “there were hard-core gamers and hobbyists, but since that time it’s become a real mass market item.”

Mr. Richards noticed an uptick in sales beginning mid-March, which was unusual. “Last December was our single best month in history of the U.S. company, but in April we almost doubled that. I’m still shocked.” The jump in people working from home because of the pandemic was likely a factor, he said.

Along with professional and amateur gamers, Secretlab’s customer base has expanded to several corporate clients including banks, Google and Shopify. “We’re seeing more people working from home, more people working long hours,” said Mr. Sin. “As a result, more people are coming to our chairs.”